ASTM E 208铁素体钢无塑性转变温度落锤试验方法_1
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名称:E208-95a(2000再认可)铁素体钢无塑性转变温度落锤试验方法本标准以固定名称e208出版;直接跟在名称后面的数字表示最初采纳的年份,假使修订,表示最近修订的年份。
在括号内的数字表示最近再认可的年份。
介绍由海军研究实验室发展而来在1952年的落锤试验方法已广泛使用于研究结构钢脆性断裂需要的起始条件。
落锤试验的设备已在好几个海军机构、研究机构和国内外的工业组织建立。
本方法用来做工业组织规范的目的和被用于好几个ASTM规范和ASTM锅炉和压力容器规范。
本程序确保试验操作在所有场合有共同的意义。
1、范围1.1本试验方法覆盖厚度大于等于5/8英寸(15.9mm)铁素体钢零塑性转变温度(DNT)的确定。
1.2本试验方法可以用于任何时候通过落锤试验方法确定常承受断裂韧性要求的钢的研究、协议、定购或规范状态。
1.3标准规定数值用英寸—磅单位。
1.4本标准不涉及所有安全地方,如果有,把它的用途联系在一起。
有责任使用该标准建立适当的安全和健康应用和确定首次使用前调整限制的适用性。
2、术语2.1定义2.2.1铁素体——用从此之后铁素体这个词指α-Fe钢。
这包括马氏体、珠光体和所有其他非奥氏体钢。
2.2.2零塑性转变温度(NDT)——依据本试验方法规定标准落锤试样断裂的最大温度。
3、试验方法概要3.1落锤试验使用特殊准备的简支梁试样,试验前在试样的拉伸面产生一个材料裂纹。
试验是通过给定材料的一系列试样(通常4-8个)在系列选定温度下受单次冲击载荷以确定单试样断裂的最大温度。
冲击载荷由一个导向的,具有250-1200 fg-lbf(340-1630 J)能量的自由落体提供,能量依据钢的屈服强度来确定。
试样被阻止而弯曲大于几十英寸。
3.2通常的系列试验如下:在做好试样的温度条件准备后,初次落锤试验的试验温度由靠近NDT温度估算出。
依据第一次的试验结果,测试的其他试样在合适的温度间隔10°F(5℃)下操作。
全国分析检测人员能力培训委员会ATM012.1金属材料落锤、撕裂试验技术考核与培训大纲第1版文件编号:ATM012.1/A:2017-1公布日期:2017年12月1总那么1.1目标了解金属材料动态撕裂、铁素体钢落锤撕裂及铁素体钢的无塑性转变温度落锤试验的差不多概念及基础理论知识;了解摆锤式冲击试验机与落锤试验机的差不多结构与工作原理;了解摆锤式冲击试验机与落锤试验机的检定项目及相关要求;掌握金属材料动态撕裂试验方法、铁素体钢的无塑性转变温度落锤试验方法与铁素体钢落锤撕裂试验方法;掌握摆锤式冲击试验机与落锤试验机的实际操作技术;掌握金属材料动态撕裂、铁素体钢落锤撕裂及铁素体钢的无塑性转变温度落锤试验的测量数据的结果处理方法。
1.2应具备的基础知识和技能1.2.1通用基础具备金属材料力学性能的基础知识。
1.2.2分析测试差不多操作具备摆锤式冲击试验机、落锤试验机及相关设备的使用能力。
1.2.3数据处理基础知识了解数据统计处理的基础知识。
2技术要求2.1ATM012-1金属落锤撕裂试验技术基础了解金属落锤撕裂试验技术的分类、特点以及相关基础知识。
2.1.1金属落锤撕裂试验技术的分类金属材料动态撕裂、铁素体钢落锤撕裂及铁素体钢的无塑性转变温度落锤试验。
2.1.2金属落锤、撕裂试验技术的特点(1)金属材料动态撕裂试验;(2)铁素体钢的无塑性转变温度落锤试验;(3)铁素体钢落锤撕裂试验。
2.1.3差不多原理(1)金属材料动态撕裂试验的差不多原理;(2)铁素体钢的无塑性转变温度落锤试验的差不多原理;(3)铁素体钢落锤撕裂试验的差不多原理。
2.1.4考核方式书面考核。
2.2ATM012-2金属落锤、撕裂试验设备与操作了解摆锤式冲击试验机与落锤试验机的差不多结构、检定项目及相关要求,掌握摆锤式冲击试验机与落锤试验机的操作技术、维护保养、期间核查和日常检查方法。
2.2.1摆锤式冲击试验机(1)差不多结构〔试验机主机架、各个系统和部件〕;(2)工作原理;(3)操作技术〔试验机的操作技术、安全规范及考前须知〕;(4)维护保养〔设备各个系统和部件的日常维护,常见故障的解决〕;(5)日常校准检查;(6)检定项目及相关要求;(7)期间核查。
ASTM 标准ASTM A6/A6M-2004 a结构用轧制钢板、型钢、板桩和棒钢通用要求ASTM A36/A36M-2004碳结构钢标准规范ASTM A106-2002a高温用无缝碳钢公称管规范ASTM A143-2003热侵镀锌结构钢制品防脆化的标准实施规程和催化探测方法ASTM A179/A179M-1990a(R2001)热交换器和冷凝器用无缝冷拉低碳钢管标准规范ASTM A192-2002高压设备用无缝碳钢锅炉管标准规范ASTM A209/A209M-2003锅炉和过热器用无缝碳钼合金钢管标准规范ASTM A210/A210M-2003锅炉和过热器用无缝中碳钢管技术条件ASTM A213/A213Mb-2004锅炉过热器和换热器用无缝铁素体和奥氏体合金钢传热管技术条件ASTM A234/A234M-2004中、高温用锻制碳钢和合金钢管道配件ASTM A252-98(R2002)焊接钢和无缝钢管桩的标准规范ASTM A262-2002a探测奥氏体不锈钢晶间腐蚀敏感度的标准实施规范ASTM A269/A269-2004通用无缝和焊接奥氏体不锈钢管标准规范ASTM A333/A333M-2004低温设备用无缝和焊接钢管的规范标准ASTM A334/A334M-2004低温设备用无缝和焊接碳素和合金钢管的标准规范ASTM A335-2003高温设备用无缝铁素体合金钢管标准规范ASTM A370/A370M-2003a钢制品力学性能试验方法和定义标准ASTM A387/A387M-2003压力容器用铬钼合金钢板的标准规范ASTM A403/A403M-2004锻制奥氏体不锈钢管配件的标准规范ASTM A450/A450M-2004碳素钢管、铁素体合金钢管及奥氏体合金钢管一般要求的标准规范ASTM A500-2003a圆形与异型冷成型焊接与无缝碳素钢结构管标准规范ASTM A515-2003中温及高温压力容器用碳素钢板的标准规范ASTM A516-2004a中温及低温压力容器用碳素钢板的标准规范ASTM A530-2003特种碳素钢和合金钢管一般要求的标准规范ASTM A615/A615M-2004a混凝土配筋用异形钢筋和无节钢胚棒标准规范ASTM A703/A703M-2004标准技术条件—承压件钢铸件通用要求ASTM A781/A781M-2004a铸件、钢和合金的标准规范及通用工业的一般性要求ASTM A788/A788M-2004a标准技术条件—钢锻件通用要求ASTM B209/B209M -2004铝和铝合金薄板和中厚板标准规范ASTM E6-2003金属材料布氏硬度的标准测试方法ASTM E18-2003金属材料洛氏硬度和洛氏表面硬度的标准测试方法ASTM E29-2002使用有效数字确定试验数据与规范符合性作法ASTM E8-2004金属材料拉伸试验的标准测试方法ASTM E94-2004放射性检查的标准指南ASTM E125-1963(R2003)铁铸件的磁粉检验用标准参考照片ASTM E164-2003焊件的超声接触检验的标准操作规程ASTM E208-1995a(R2000)用导向落锤试验测定铁素体钢无塑性转变温度的标准试验方法ASTM E213-2004金属管超声检验方法ASTM F36-1995测定垫片材料压缩率及回弹率的标准试验方法ASTM F37-1995垫片材料密封性的标准试验方法ASTM F38-1995垫片材料的蠕变松弛的标准试验方法ASTM F112-1995色覆垫片密封性能的标准试验方法ASTM F146-1995a垫片材料耐液体标准试验方法ASTM F1311-1995(R2001)大口径组装式碳钢法兰标准规范ASTM G1-2003腐蚀试样的制备、清洁处理和评定用标准实施规范ASTM G36-73(R1981) 参考资料标准实用规程:在沸的氯化镁溶液中进行的应力腐蚀裂纹试验ASTM G46-1976(R1986) 参考资料标准实用规程:麻点腐蚀的检验和评定ASTM G48-1976(R1980) 参考资料使用三氯化铁溶液做不锈钢及其合金的耐麻点腐蚀和抗裂口腐蚀性试验的标准方法ASTM标准中译本丛书(一)碳钢、铸铁、不锈钢及合金钢材料标准规范(含18个标准)ASTM A105/A105M-2002管道部件用碳钢锻件ASTM A126-1995(R2001)阀门、法兰和管道附件用灰铁铸件ASTM A181/A181M-2001通用管路用碳钢锻件标准规范ASTM A193/A193M-2001高温用合金钢和不锈钢螺栓材料ASTM A194/A194M-2001 a高温用合金钢和不锈钢螺栓材料ASTM A216/A216M-2001 a高温用可熔焊碳钢铸件标准规范ASTM A217/A217M-2002高温承压件用马氏体不锈钢和合金钢铸件标准规范ASTM A276-2002 a不锈钢棒材和型材ASTM A278/A278M-2001高温不超过650°F(350℃)的承压部件用灰铸铁件ASTM A320/A320M-2002低温用合金钢栓接材料ASTM A350/A350M-2002要求冲击韧性试验的管件用碳钢及低合金钢锻件标准规范ASTM A351/A351M-2000承压件用奥氏体、奥氏体-铁素体(双相)钢铸件规范ASTM A352/A352M-1993(R1998)低温承压件用铁素体和马氏体钢铸件标准规范ASTM A395/A395M-1999高温用铁素体球墨铸铁承压铸件ASTM A439-1983(R1999)奥氏体球墨铸铁件ASTM A536-1984(R1999)球墨铸铁件ASTM A694/A694M-2000高温输送用管法兰、管件、阀门及零件用碳钢和合金钢锻件标准规范ASTM A965/A965M-2002高温高压部件用奥氏体钢锻件ASTM标准中译本丛书(二)法兰、管件、阀门及部件(含9个标准)ASTM A182/A182M-2002高温用锻制或轧制合金钢法兰、锻制管件、阀门和部件ASTM A961-2002管道用钢制法兰、锻制管件、阀门和零件的通用要求标准规范ASTM B462-2002高温耐腐蚀用锻制或轧制的UNS NO6030、UNS NO6022、UNS NO6200、UNS NO8020、UNS NO8024、UNS NO8026、UNS NO8367、UNS NO10276、UNS N10665、UNS N10675和UNS R20033合金管法兰、锻制管件、阀门和零件标准规范外形尺寸标准规范ASTM F992-1986(R2001)阀门铭牌标准规范ASTM F885-1984公称管径为NPS 1/4~2的青铜截止阀ASTM F993-1986(R2001)阀门锁紧装置标准规范ASTM F1030-1986(R1998)阀门操作装置的选择准则ASTM F1098-1987(R1998)公称管径有NPS2~24的蝶阀外形尺寸标准规范ASTM F1565-2000蒸汽用减压阀规范参考资料:外国标准中文版(ASTM 美国材料与试验协会标准中文版)美国ASTM标准简介成立于1898年的ASTM International(美国试验与材料学会国际组织)是目前世界上最大的制定自愿性标准的组织。
a)内角焊缝 b)外侧角焊缝
图5 U形肋熔透角焊缝宏观断面
5 结束语
通过采用板单元U形肋内焊+外焊的方式,实现
图1 B 组评定焊接参数2落锤试样
3.4 B 组落锤试验
用B 组落锤试样测定材料的N D T T 温度,结果,采用B 组落锤试样测得材料的NDTT 温度为℃。
表5 B 组落锤试验
试验温度/℃落锤能量/J 试样类型
试验结果焊接工艺
-22400P-2断裂参数-17400P-2未断裂-17400P-2断裂-12400P-2未断裂-12
400
P-2
未断裂
a )D14试样裂纹源焊道局部放大
b )D15试样裂纹源焊道局部放大
C )D16试样裂纹源焊道局部放大
a) 焊道(200×) b)靠近焊道热影响区(200×)
图3 用参数1电流堆焊试样各区显微组织
a)焊道(200×) b)靠近焊道热影响区(200×)图4 用参数2电流堆焊试样各区显微组织
5 结束语
1)经过试验,焊接电流为160~170A的焊接工艺符合ASTM E208第7.10.3节关于评定裂纹源焊道
焊接工艺的要求,可用于落锤试样制备。
2)两种工艺焊接电流相差约20A,对于SA-508 Gr.3Cl.1材料,相对于ASTM E208标准推荐的焊接。
落锤试验测定船板的无塑性转变温度郑香增,夏佃秀,李兴芳(济南钢铁集团总公司,山东济南 250101)摘要:无塑性转变温度是安全设计的重要参量,广泛应用于材料研究和产品质量控制过程。
利用落锤试验方法,测定了AH36级船板的无塑性转变温度为-25℃,并对试验结果进行了评定。
结果表明,落锤试验方法简单,试验数据重复性好,当船板的服役温度高于NDTT时,基本保证船板不会发生脆断。
关键词:落锤试验;无塑性转变温度;AH36船板;裂纹扩展中图分类号:TG115.5+ 6 文献标识码:B 文章编号:1004-4620(2004)01-0057-02Determination of Nil-ductility Transition Temperatureof Ship Plate by Drop Weight TestZHENG Xiang-zeng, XIA Dian-xiu, LI Xing-fang(Jinan Iron and Steel Group, Jinan 250101, China)Abstract:Nil-ductility transition temperature is an important parameter for safety design and it is wide used in material research and control process of product quality The nil-ductility transition temperature of AH36 ship plate is -25℃ which is determined by drop weight test method. The result is stated that the drop weight test is a good and simple method and has good repetitiveness of experimental data. The brittle fracture occurred in AH 36 can be avoided basically when the service temperature is higher than nil-ductility transition temperature.Keywords:drop weight test;nil-ductility transition temperature;AH36 ship plate; crack growth铁素体结构钢的韧性随温度下降而降低,当温度降到某一值时,达到临界点,此时断口完全呈结晶状脆性断裂状态,这一温度称为无塑性转变温度(NDTT),是以下阶能开始上升的温度定义的韧脆转变温度,表征含有小裂纹的钢材在动态加载屈服应力下发生脆断的最高温度。
核电站设备用主要金属材料落锤试验中焊接材料及焊接工艺的确定陈增芳;郭平;汪垠【摘要】Various welding metals and processes specifications of drop test criteria both at home and abroad have been described.During actual test operation, application of certain welding metal and process were supposed to select according to applicable criterion , which has positive guidance for working out accurate test results .% 介绍了落锤试验国内外标准中对焊接材料及焊接工艺的不同规定,在实际试验中根据采用的标准选取合适的焊材和工艺,对获得准确的试验结果有很好的指导作用。
【期刊名称】《中国重型装备》【年(卷),期】2013(000)001【总页数】3页(P34-35,38)【关键词】核电站设备;材料;无塑性转变温度;焊接材料;焊接工艺;标准;试验【作者】陈增芳;郭平;汪垠【作者单位】中国核电工程有限公司,北京100080;中核能源科技有限公司,北京100193;中核能源科技有限公司,北京100193【正文语种】中文【中图分类】TG422.1;TG455核电站主要设备,例如核岛部分的压力容器、蒸汽发生器、稳压器和主管道等主要承压设备的壳体部分,是由核级锻件或钢板组焊而成,在使用中要承受高温高压。
因此,对锻件和钢板的拉伸、冲击和弯曲等力学性能要求都很高,另外,一般还要进行无塑性转变温度TNDT(nil ductility transition temperature)的测试,即要进行落锤试验。
落锤试验通常采用的试验标准有:GB/T6803、ASTM E208、RCC-M MC1320。
钢材落锤撕裂试验方法概述说明以及解释1. 引言1.1 概述钢材是一种非常重要的材料,在各个领域广泛应用。
然而,为了确保钢材的质量和可靠性,需要进行一系列的试验来评估其性能和强度。
其中,落锤撕裂试验方法是一种常用且有效的手段,用于评估钢材在受到冲击时的耐久性和韧性。
1.2 文章结构本文将从以下几个方面对落锤撕裂试验方法进行详细描述。
首先,将给出该试验方法的定义与原理,以便读者更好地理解其背后的科学原理。
其次,我们将介绍执行这一试验所需的步骤和操作流程。
最后,文章还将就试验结果进行分析,并讨论可能的影响因素。
1.3 目的本文旨在全面介绍落锤撕裂试验方法,并探讨它在钢材研究和生产中的应用。
通过深入了解这一试验方法及其意义,希望能够提供给读者一个清晰而全面的视角,并为相关研究工作提供有价值的参考依据。
(注:以上回答仅供参考,具体内容可根据实际情况进行调整。
)2. 落锤撕裂试验方法2.1 定义与原理落锤撕裂试验方法是一种常用的测试手段,用于评估材料在快速加载条件下的韧性和抗拉强度。
该方法通过加载一个尖锐或缺口形状的试样,然后使用一枚高速下落的重锤施加冲击力,使得试样发生断裂或撕裂。
通过测量试样破坏前后的尺寸变化和应力分布等参数,可以得到材料的抗拉强度和韧性等性能指标。
2.2 实施步骤落锤撕裂试验通常包括以下几个步骤:1. 选择合适的试样: 根据不同标准和要求,在钢材中选择代表性的试样进行测试。
常见的试样形状包括板状、圆柱状或带有特定缺口形状。
2. 准备工作: 对选定的试样进行必要的切割、加工和打磨处理,保证其尺寸和表面质量符合要求。
3. 安装仪器设备: 将试样放置在适当的支架上,并确保其固定稳定。
调整好落锤和传感器的位置,并确保仪器设备处于正常工作状态。
4. 进行测试: 控制好落锤下落的高度和速度,让其与试样产生冲击。
记录并测量实验过程中的数据,包括试样的位移、应力以及载荷等参数。
5. 数据处理与分析: 根据实验所得数据,进行相关的计算和分析。
落锤撕裂试验方法及其应用毕传堂、刘家驹、蒋和岁摘要本文所介绍的落锤试验方法是近些年来国际上发展并投入应用的一种新的工程试验方法,该试验方法在评定管线用钢的使用性能以及其它方面的用途中行之有效、简单方便、经济实用,能准确地给出不同设计准则下对母材的防断或止裂性能的温度要求。
一、前言落锤撕裂试验是六十年代中期美国海军研究所的Puzak 和Penini 与Bethlehem 钢铁公司Homer 研究所为解决石油管线的实际使用性能的评定问题而提出来的。
1974 年该试验方法正式列为ASTM 标谁(标准号ASTME436 - 74 )〔1〕〔2〕。
落锤撕裂试验(以下简称DWTT )是属于模拟输运管道和圆桶型压力容器破坏型态的动态工程试验方法,其试样的断口特性与输油管道和压力容器破坏时的断裂传播断口特性非常相似〔3 , 4 , 5〕。
该试验方法简单易行,能明显地反映出试样断口随温度降低的急剧转变。
同时由于DWTT 试样的厚度等于原管壁厚度,所以也能给出转变温度的厚度效应。
因此该试验方法在评定管线用钢的实际使用性能等方面是一种行之有效、简单方便、经济实用的工程试验方法,能准确地给出不同设计准则下对母材的防断或止裂性能的温度要求。
二、DWTT 的美国ASTM 标准1 .试样与试验的特点DWTT 的美国ASTM 标准中,试样的尺寸为:3 ±1/8英寸×12±3/4英寸×原板厚,即,“76.2 士3 . 175 X 305 X19 .05 X原板厚mm 。
为方便应用,在原公差范围内可取为75±0. 5x300 ±5 ×原板厚mm ,见图1。
厚度为3 ~19mm 。
在试验中,试样宽度在57 到114mm 范围内对试验结果没有影响〔 3 ]。
试样较宽为断裂传播提供了足够长的传播途径,加之试样为原板厚,更便于充分揭示试验钢种断裂传播抗力的变化和冶金质量的波动以及厚度效应。
Designation:E208–06Standard Test Method forConducting Drop-Weight Test to Determine Nil-Ductility Transition Temperature of Ferritic Steels1This standard is issued under thefixed designation E208;the number immediately following the designation indicates the year of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.INTRODUCTIONThis drop-weight test was developed at the Naval Research Laboratory in1952and has been used extensively to investigate the conditions required for initiation of brittle fractures in structural steels. Drop-weight test facilities have been established at several Naval activities,research institutions,and industrial organizations in this country and abroad.The method is used for specification purposes by industrial organizations and is referenced in several ASTM specifications and the ASME Boiler and Pressure Vessel Code.This procedure was prepared to ensure that tests conducted at all locations would have a common meaning.This test method was originally published as Department of the Navy document NA VSHIPS-250-634-3.1.Scope*1.1This test method covers the determination of the nil-ductility transition(NDT)temperature of ferritic steels,5⁄8in.(15.9mm)and thicker.1.2This test method may be used whenever the inquiry, contract,order,or specification states that the steels are subject to fracture toughness requirements as determined by the drop-weight test.1.3The values stated in inch-pound units are to be regarded as the standard.1.4This standard does not purport to address all of the safety concerns,if any,associated with its use.It is the responsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1ASTM Adjuncts:Drop Weight Machine23.Terminology3.1Definitions:3.1.1ferritic—the word ferritic as used hereafter refers to all a-Fe steels.This includes martensitic,pearlitic,and all other nonaustenitic steels.3.1.2nil-ductility transition(NDT)temperature—the maxi-mum temperature where a standard drop-weight specimen breaks when tested according to the provisions of this method.4.Summary of Test Method4.1The drop-weight test employs simple beam specimens specially prepared to create a material crack in their tensile surfaces at an early time interval of the test.The test is conducted by subjecting each of a series(generally four to eight)of specimens of a given material to a single impact load at a sequence of selected temperatures to determine the maximum temperature at which a specimen breaks.The impact load is provided by a guided,free-falling weight with an energy of250to1200ft-lbf(340to1630J)depending on the yield strength of the steel to be tested.The specimens are prevented by a stop from deflecting more than a few tenths of an inch.4.2The usual test sequence is as follows:After the prepa-ration and temperature conditioning of the specimen,the initial drop-weight test is conducted at a test temperature estimated to be near the NDT temperature.Depending upon the results of thefirst test,tests of the other specimens are conducted at suitable temperature intervals to establish the limits within 10°F(5°C)for break and no-break performance.A duplicate test at the lowest no-break temperature of the series is conducted to confirm no-break performance at this tempera-ture.1This test method is under the jurisdiction of the ASTM Committee E28onMechanical Testing and is the direct responsibility of Subcommittee E28.07onImpact Testing.Current edition approved Nov.15,2006.Published November2006.Originallyapproved st previous edition approved in2000as E208–95a(2000)e1.2Detail drawings for the construction of this machine are available from ASTMHeadquarters.Order ADJE0208.Original adjunct produced in2002.*A Summary of Changes section appears at the end of this standard. Copyright©ASTM International,100Barr Harbor Drive,PO Box C700,West Conshohocken,PA19428-2959,United States.4.3In1984,the method of applying the crack-starter weld bead was changed from a two-pass technique to the current single-pass procedure,and the practice of repair-welding of the crack-starter weld bead was prohibited.For steels whose properties are influenced by tempering or are susceptible to temper embrittlement,the nil-ductility transition(NDT)tem-perature obtained using the single-pass crack-starter weld bead may not agree with that obtained using the previous two-pass crack-starter weld bead,or when the crack-starter bead was repaired.5.Significance and Use5.1The fracture-strength transitions of ferritic steels used in the notched condition are markedly affected by temperature. For a given“low”temperature,the size and acuity of theflaw (notch)determines the stress level required for initiation of brittle fracture.The significance of this test method is related to establishing that temperature,defined herein as the NDT temperature,at which the“smallflaw”initiation curve,Fig.1, falls to nominal yield strength stress levels with decreasing temperature,that is,the point marked NDT in Fig.1.5.2Interpretations to other conditions required for fracture initiation may be made by the use of the generalizedflaw-size, stress-temperature diagram shown in Fig.1.The diagram was derived from a wide variety of tests,both fracture-initiation and fracture-arrest tests,as correlated with the NDT tempera-ture established by the drop-weight test.Validation of the NDT concept has been documented by correlations with numerous service failures encountered in ship,pressure vessel,machinery component,forged,and cast steel applications.6.Apparatus6.1The drop-weight machine is of simple design based on the use of readily available structural steel products.2The principal components of a drop-weight machine are a vertically guided,free-falling weight,and a rigidly supported anvil which provides for the loading of a rectangular plate specimen as a simple beam under the falling weight.Fig.2(a)illustrates a typical drop-weight machine built of standard structural shapes.6.2A rail,or rails,rigidly held in a vertical position and in afixed relationship to the base shall be provided to guide the weight.The weight shall be provided with suitable devices which engage the rail,or rails,and ensure that it will drop freely in a single,vertical plane.The weight may be raised by any convenient means.A weight-release mechanism,function-ing similarly to that shown in Fig.2(b),shall be provided to release the weight quickly without affecting its free fall.The weight shall be made in one piece,or if made of several pieces, its construction shall be rigid to ensure that it acts as a unit when it strikes the specimen.The striking tup of the weight shall be a steel cylindrical surface with a radius of1in.(25.4 mm)and a minimum hardness of HRC50throughout the section.The weight shall be between50and300lb(22.7and 136kg).The rails and hoisting device shall permit raising the weight variousfixed distances to obtain potential energies of 250to1200ft-lbf(340to1630J).6.3A horizontal base,located under the guide rails,shall be provided to hold and position precisely the several styles of anvils required for the standard specimens.The anvil guides shall position the anvil with the center-line of the deflection stops under the center-line of the striking tup of the weight.In general,the base will also support the guide rails,but this is not a requirement.The base shall rest on the rigid foundation.The base-foundation system shall be sufficiently rigid to allow the normal drop-weight energy(Table1)to deflect a standard specimen to the stop at temperatures above the NDT.The base shall not jump or shift during the test,and shall be secured to the foundation if necessary to prevent motion.6.4A guard screen,similar to that shown in Fig.2(c),is recommended to stop broken specimen halves of the very brittle steels which break into two pieces with both halves being ejected forcefully from the machine.6.5The general characteristics of two of the anvils required are illustrated in Fig.3.The anvils shall be made inaccordance FIG.1Generalized Fracture Analysis Diagram Indicating the Approximate Range of Flaw Sizes Required for Fracture Initiation at Various Levels of Nominal Stress,as Referenced by the NDT Temperature,(a )Left —Complete Assembly(b )Upper Right —Quick Release Mechanism (c )Lower Right —Guard ScreenFIG.2Drop-Weight Test ApparatusTABLE 1Standard Drop-Weight Test ConditionsType of SpecimenSpecimen Size,in.(mm)Span,in.(mm)Deflection Stop,in.(mm)Yield Strength Level,ksi (MPa)Drop-Weight Energy for GivenYield Strength Level Aft-lbf J P-11by 31⁄2by 14(25.4by 89by 356)12.0(305)0.3(7.6)30to 50(210to 340)50to 70(340to 480)70to 90(480to 620)90to 110(620to 760)60080010001200800110013501650P-23⁄4by 2by 5(19by 51by 127)4.0(102)0.06(1.5)30to 60(210to 410)60to 90(410to 620)90to 120(620to 830)120to 150(830to 1030)250300350400350400450550P-35⁄8by 2by 5(15.9by 51by 127)4.0(102)0.075(1.9)30to 60(210to 410)60to 90(410to 620)90to 120(620to 830)120to 150(830to 1030)250300350400350400450550AInitial tests of a given strength level steel shall be conducted with the drop-weight energy stated in this column.In the event that insufficient deflection is developed (no-test performance)an increased drop-weight energy shall be employed for other specimens of the givensteel.with the dimensions shown in Fig.4.The anvil supports and deflection stops shall be steel-hardened to a minimum hardness of HRC 50throughout their cross section.The space between the two stops is provided as clearance for the crack-starter weld on the specimen.The deflection stops may be made in two separate pieces,if desired.The anvil-base system shall be sufficiently rigid to allow the normal drop-weight energy (Table 1)to deflect the specimen to the stop at temperatures well above the NDT.6.6A measuring system shall be provided to assure that the weight is released from the desired height for each test,within the limits of +10,−0%.6.7Modifications of the equipment or assembly details of the drop-weight machine shown in Fig.2are permitted provided that the modified machine is functionally equivalent.Fig.5illustrates a portable machine design used by an industrial concern for drop-weight tests of materials used for pressure vessel components at different fabrication sites.7.Precautions7.1The drop-weight test was devised for measuring fracture initiation characteristics of 5⁄8-in.(15.9-mm)and thicker struc-tural materials.This test is not recommended for steels less than 5⁄8-in.thick.7.2This test method establishes standard specimens and conditions to determine the NDT temperature of a given steel.The use of standard specimens with nonstandard test condi-tions or the use of nonstandard specimens shall not be allowed for specification purposes.7.3This test method employs a small weld bead deposited on the specimen surface,whose sole purpose is to provide a brittle material for the initiation of a small,cleavage crack-flaw in the specimen base material during the test.Anomalous behavior may be expected for materials where the heat-affected zone created by deposition of the crack-starter weld is made more fracture resistant than the unaffected plate.This condition is developed for quenched and tempered steels of high hard-ness obtained by tempering at low temperatures.The problem may be avoided by placing the crack-starter weld on these steels before conducting the quenching and tempering heat treatment.Except for other cases which may be readily rationalized in metallurgical terms (for example,it is possible to recrystallize heavily cold-worked steels in the heat-affected zone and to develop a region of improved ductility),the heat-affected zone problem is not encountered with conven-tional structural grade steels of a pearlitic microstructure or quenched and tempered steels tempered at high temperatures to develop maximum fracture toughness.8.Test Specimens8.1Identification of Material —All sample material and specimens removed from a given plate,shape,forging,or casting product shall be marked to identify their particular source (heat number,slab number,etc.).A simpleidentificationFIG.3General Appearance of the Anvils Required for Drop-Weight NDTTestssystem shall be used which can be employed in conjunctionwith an itemized table to obtain all the pertinent information.8.2Orientation —The drop-weight test is insensitive to specimen orientation with respect to rolling or forging direc-tion.However,unless otherwise agreed to,all specimens specified by the purchaser shall be of the same orientation and it shall be noted in the test report.8.3Relation to Other Specimens —Unless otherwise speci-fied by the purchaser,the specimens shall be removed from the material at positions adjacent to the location of other type test specimens (for example,mechanical test specimens)required for evaluation of other material properties.8.4Special Conditions for Forgings and Castings —Where drop-weight testing of cast or forged material is specified,the size and location of integrally attached pad projections or prolongations to be used for specimen fabrication shall be agreed to in advance by the purchaser.If the design of the casting or forging does not allow an attached test-material coupon,the following requirements shall apply:8.4.1Drop-weight specimens cast or forged separately to the dimensions required for testing shall be allowed only where the product dimensions are equivalent and the purchaser agrees.8.4.2Specimens may be taken from a separately produced test-material coupon if the supplier can demonstrate that it is equivalent to the product with respect to chemical composition,soundness,and metallurgical conditions.The material shall be from the same heat and shall have been fabricated under identical conditions as the product.The specimens shall be machine-cut from locations agreed to in advance by the purchaser.8.4.3Specifically,in the case of casting requiring X-ray quality standard,the separate test-material coupon shall be cast separately but simultaneously with the product.Chills shall not be used.The test-material coupon shall be in proportion to the thickness,T,in the cast product,where T is diameter of the largest circle that can be inscribed in any cross section oftheAnvil Dimension UnitsSpecimen Type ToleranceP-1P-2P-3S ,Spanin.mm 12.0305 4.0100 4.010060.0561.5D ,Deflection stop in.mm 0.307.600.0601.500.0751.9060.00260.05A ,Anvil length ←——————––not critical––——————→B ,Anvil width ←——————––not critical––——————→C ,Anvil thickness in.mm 1.5min 38min 1.5min 38min 1.5min 38min E ,Support length in.mm 3.5min 90min 2.0min 50min 2.0min 50minF ,Support width ←——————not less thanG ——————→G ,Support height in.mm 2.050 2.050 2.05061625R ,Support radius in.mm 0.0751.00.0751.00.0751.060.02560.1H ,Stop width in.mm 3.5min 90min 2.0min 50min 2.0min 50min 62650I ,Weld clearance in.mm 0.9220.9220.92260.163J ,Weld clearance depthin.mm 0.4min 10min 0.4min 10min 0.4min 10minFIG.4AnvilDimensionscasting,or where T is defined in advance by the purchaser as the nominal design thickness,as follows:Thickness,T ,in.(mm)Separately Cast,Nonchilled,Test-Coupon Size 1⁄2(12.7)and less None required5⁄8to 2(15.9to 50.8)When several small castings are poured from one heat,one casting shall be used to provide test specimens,if adaptable5⁄8to 1(15.9to 25.4)T by 2by 5in.(127mm)for irregularly shaped cast-ings>1to 3(25.4to 76.2)>3to 5(76.2to 127)T by 4.5T by 4.5T T by 3T by 3TOver 5(127)T by 3T by 3T for castings that are representative of cast platesOver 5(127)T by T by 6=T for castings that are representative of cast plates8.4.4Specimens showing casting or metallurgical faults on broken fracture surfaces shall be “No-Test.”8.5Size of Blank —Dimensions of the blank size required for standard test specimens are shown in Fig.6.Equally significant NDT temperatures,within 610°F (65°C),aredetermined for a given steel with tests using any of the standard specimens.As may be convenient for the particular thickness of material,any of the standard specimens shown in Fig.6and prepared as described in Section 8may be chosen for this method.The results obtained with standard test conditions shall comply with the requirements of this method for deter-mining the NDT temperature.8.6Specimen Cutting —The specimen sample material and the specimen ends may be flame-cut.The specimen sides shall be saw-cut or machined,using adequate coolant to prevent specimen overheating,and shall be a minimum of 1in.from any flame-cut surface.Products thicker than the standard specimen thickness shall be machine-cut to standard thickness from one side,preserving an as-fabricated surface unless otherwise specified,or agreed to,in advance by the purchaser.The as-fabricated surface so preserved shall be the welded (tension)surface of the specimen during testing.8.7Crack-Starter Weld —The crack-starter weld,which is a centrally located weld bead,approximately 2in.(50mm)long (WL of Fig.6)and 1⁄2in.(12.7mm)wide,shall be deposited on the as-fabricated tension surface of the drop-weight speci-men in a single pass.To assist the welding operator in centering the weld deposit properly on the test piece,two punch marks spaced to the appropriate WL dimension of Fig.6shall be positioned as A and D as shown in Fig.7(a).As an alternative to the punch marks,a copper template containing a centrally positioned slot,1in by WL +1⁄2in.(25mm by WL +13mm)Fig.7(b),may be used.See Note 1and Fig.7(b).The weld shall start from either Point A or D and shall proceed without interruption as a stringer bead (no weaving)to the other point.The bead appearance is determined by the amperage,arc voltage,and speed of travel used.A current of 180to 200A,a medium arc length,and a travel speed that will result in a moderately high-crowned bead have been found to be suitable conditions.An enlarged view of an as-deposited crack-starter weld is shown in Fig.7(c ).“Each lot of electrodes shall be checked by the user in accordance with the requirements of 8.10for suitability with the material the user is testing.Providing a heat sink under P-2and P-3specimens during welding is recommended but not required in order to minimize microstructural changes to these smaller specimens.Both metallic and water-box heat sinks have been used for this purpose.N OTE 1—The copper template is especially recommended for the Type P-2and P-3specimens since in addition to heat sink advantages it eliminates weld spatter which may interfere with proper seating of the specimen during test.8.7.1Microstructure of Base Metal —Data presented show that the method of depositing the weld bead can influence the microstructure of the heat-affected zone under the weld notch which in turn can influence the NDT determined especially in heat-treated steels.38.8Weld Notch —The final preparation of the specimen consists of notching the deposited weld at the center of the bead length.Care shall be taken to ensure that only the weld3Tsukada,H.,Suzuki,I.I.,and Tanaka,Y .,“A Study on Drop-Weight Test Using A508Class 2Steel,”Japan Steel Works,Ltd.,December 1,1981.FIG.5Portable Drop-Weight Test Machine Used for Tests atDifferent FabricationSitesdeposit is notched and that the cutting tools do not contact the specimen surface.The notch may be cut with thin abrasive disks,as shown in Fig.8,or other convenient cutting tools such as mechanical saws,hack saws,etc.,or electrical discharge machining.The weld-notch details and a representative ex-ample of a notched weld are given in Fig.9.8.9Measuring Weld-Notch Depth —The depth of the notch from the crown of the weld will vary with expected variations in weld-crown dimensions.The depth of the notch is not measured,since it is the thickness of the weld remaining above the specimen and under the bottom of the notch that has been standardized,as shown in Fig.9.This weld thickness above the specimen shall be maintained across as much of the weld width as permitted by the bead contour.Fig.10illustrates an optional device for measuring the thickness of weld metal at the bottom of the notch.The adjustable dial indicator with bridge-support is set at zero while in position on the specimen with the indicator tip contacting the specimen surface immediately adjacent to the notch.The bridge is then placed over the weld with the indicator tip resting on the bottom of the notch to measure the weld metal thickness directly.After the operator has gained experience in the preparation of a few specimens,the instrument need be used only in the final checking of the finished notch.8.10Other Crack-Starter Welds —The satisfactory comple-tion of drop-weight tests is dependent upon the “crack-starting”conditions developed by the notched weld.As shown sche-matically in Fig.11,the specimen deflection,D C ,that cracks the weld,is significantly less than the allowable anvil stop deflection,D A ,for all standard thickness,T,specimens tested on the proper span,S.The carefully prepared and specially handled electrode (described in 8.7)has been proved success-ful for crack-starting purposes for all temperatures up to approximately 400°F (200°C).Other weld materials shall be considered to perform satisfactorily as crack-starters if they also develop cleavage cracks at suitably high test temperatures at or near the instant that yielding occurs in the surface fibers of the test specimen.Weld materials,other than those described in 8.7,may be used for the crack-starter bead provided the following requirements are met:8.10.1Using standard conditions as specified in Table 1,three standard Type P-2specimens (3⁄4by 2by 5in.)(19by 51by 127mm)shall be drop-weight tested at a temperature 100°F (55°C)or more above the NDT temperatures of the plate material.8.10.2If the three tests demonstrate that the weld notch is always cracked upon deflection of the specimen tension surface to the maximum amount permitted by the proper anvil stop,the other crack-starter weld shall be authorized and considered to conform to the requirements of this method.8.10.3Welding procedures or crack-starter weld dimensions other than those described in 8.7shall be considered to perform satisfactorily as crack-starters if they are demonstrated to develop cleavage cracks at suitably high test temperatures at or near the instant that yielding occurs in the surface fibers of the test specimens.For example,a 3⁄4to 1-in.long crack-starter weld deposited in one direction only with the welding condi-tions and the electrodes described in 8.7has been used successfully as a crack-starter weld for the Type P-3specimen.The shorter weld reduces to total heat input into the specimen and is considered less likely to cause metallurgical changes in the specimen base materials of the low-alloy,high-tensile strength pressure vessel steels.For the Type P-1specimen,theDimension Units Specimen TypeP-1P-2P-3Dimension Tolerance Dimension Tolerance DimensionTolerance T ,Thickness in.mm 1.02560.1262.50.751960.0461.00.621660.0260.5L ,Length in.mm 14.036060.5610 5.013060.5610 5.013060.5610W ,Width in.mm 3.59060.162.0 2.05060.0461.0 2.05060.0461.0WL ,Weld lengthin.mm2.563.5616251.7544.561.06251.7544.561.0625.0N OTE 1—The length of the weld bead is not critical,provided that the crack-starter notch is at the center of specimen and that the weld bead does not contact the support fixture when the specimen is fully deflected.FIG.6Standard Drop-Weight SpecimenDimensionsFIG.7Methods of Locating the Weld Deposit Properly on the Test SpecimenN OTE1—The weld shown does not comply with the current procedure which specifies that the weld shall start from either end and shall proceed without interruption.FIG.8Notching of Crack-Starter Weld Depositshorter weld does not provide the reproducibility or consis-tency for crack-starting purposes obtained with the standardcrack-starter weld described in 8.7.Other welding procedures or crack-starter weld dimensions than those described in 8.7may be used as the crack-starter bead for a given standard type (P-1,P-2,or P-3)specimen provided that three specimens are tested in accordance with 8.10.1and results obtained in accordance with 8.10.2.9.Procedure—General9.1Some care and thought are necessary to make a success-ful drop-weight determination of the NDT temperature.Ad-equate auxiliary equipment and a definite procedure will aid in making the test.The following sections will define in detail and in orderly fashion the equipment and procedure requirements:9.2Conduct the test by placing a specimen in a heating or cooling device until it is at the desired temperature.Then place it with minimum loss of time (see 13.4)on the anvil and align where it will be struck squarely by the weight.Allow the weight to drop from a known preselected height on the specimen.Examine the specimen after the strike to determine its condition as defined by the requirements of this method.Repeat this process until the NDT temperature has been determined.9.3The number of specimens required to determine the NDT temperature is a function of the experience of the operator with the material and of the use of an adequate procedure.A skilled operator working with known material can determine the NDT temperature with as few as three speci-mens.Generally,six to eight specimens are required.10.Specimen—Anvil Alignment10.1Anvil Requirements —Test each type of drop-weight specimen only on the anvil designated for that type specimen in accordance with Table 1.10.2Specimen-Anvil Alignment —In order to obtain a valid test properly align the specimen on the anvil.Align the specimen,anvil,and weigh so the specimen is struck under the following conditions:10.2.1The specimen shall be horizontal and the ends shall rest on the anvil supports.10.2.2The striking tup of the weight shall strike within 60.1in.(62.5mm)of a line on the compression side of the specimen,normal to a long edge and directly opposite the notch in the crack-starter weld.10.2.3No part of the crack-starter weld will touch the deflection stops at any time during the test.10.2.4The specimen sides and ends shall be free from any interference during the test.10.3Alignment Tool —The optional technique shown in Fig.12has been used successfully to achieve longitudinal and angular specimen alignment of the specimen.Draw a wax-pencil line on the compression surface of the specimen normal to a long edge and directly opposite the notch.Place the specimen on the anvil so this line coincides with the edge of a removable guide bar.Place the bar against the machine rails so that its edge defines the striking line of the tup on the weight.11.Selection of Test Energy11.1Strike the specimen by a free-falling weight having adequate energy to deflect the specimen sufficiently tocrackFIG.9Weld-Notch Details and Example of a NotchedWeldFIG.10Method for Measuring Weld Metal Thickness at theBottom of theNotchFIG.11Drop-Weight TestMethodthe weld deposit and to make the tension surface contact the anvil stop.The design of the machine permits the use of various impact energies to accommodate the different strength levels of the various materials tested.The standard test conditions shown in Table 1have been developed by experi-ence and shall be used for the test series of a given steel unless “No-Test”performance is experienced.The indicated energies can be obtained by lifting the weight the required distance from the compression surface of the specimen.11.2Proper contact of the tension surface of the specimen with the deflection stop may be defined as follows:Scribe a wax-pencil line on the tension surface of a standard specimen parallel to and in line with the mechanical notch cut in the crack-starter weld deposit,Fig.13(a ).Apply clean masking tape,or a similar material,to the top surface of the anvil deflection stop blocks,Fig.13(b ).Align the test specimen on the anvil and strike once by the weight with the standard conditions,Table 1,for the steel involved.Transfer of the wax-pencil line from specimen to the tape or visible evidence of specimen contact with the tape shall indicate that thespecimen was bent sufficiently (Fig.13(c )).The above proce-dure,to ensure proper contact of the tension surface of the specimen with the deflection stop blocks,is considered a “built-in”standardization feature of the test method,and it shall be employed for each drop-weight test to preclude “No-Test”performance as described in 14.2.3and 14.3.11.3If the weld crack and anvil stop contact criteria are not met by the Table 1energies,increase the drop-weight energy in 100-ft-lb increments for the Type P-1specimens or 50-ft-lb (68-J)increments for the Type P-2and P-3specimens until they are met.Do not use drop-weight energies above those posted on the table unless the above procedure has been followed to determine the excess energy requirements.12.Selection of Test Temperatures12.1The selection of test temperatures is based on finding,with as few specimens as possible,a lower temperature where the specimen breaks and an upper temperature where it does not break,and then testing at intervals between these tempera-tures until the temperature limits for break andno-breakFIG.12Method for Alignment ofSpecimen(a )(b )(c )(a )Wax Pencil Line Scribed on Tension Side of a Specimen (b )Application of Masking Tape to Anvil Stop Surfaces(c )Transfer of Wax Lines to the Tape When the Specimen Hits the StopFIG.13Method Employed to Indicate Contact of the Specimen with the AnvilStop。
名称:E208-95a(2000再认可)铁素体钢无塑性转变温度落锤试验方法本标准以固定名称e208出版;直接跟在名称后面的数字表示最初采纳的年份,假使修订,表示最近修订的年份。
在括号内的数字表示最近再认可的年份。
介绍由海军研究实验室发展而来在1952年的落锤试验方法已广泛使用于研究结构钢脆性断裂需要的起始条件。
落锤试验的设备已在好几个海军机构、研究机构和国内外的工业组织建立。
本方法用来做工业组织规范的目的和被用于好几个ASTM规范和ASTM锅炉和压力容器规范。
本程序确保试验操作在所有场合有共同的意义。
1、范围1.1本试验方法覆盖厚度大于等于5/8英寸(15.9mm)铁素体钢零塑性转变温度(DNT)的确定。
1.2本试验方法可以用于任何时候通过落锤试验方法确定常承受断裂韧性要求的钢的研究、协议、定购或规范状态。
1.3标准规定数值用英寸—磅单位。
1.4本标准不涉及所有安全地方,如果有,把它的用途联系在一起。
有责任使用该标准建立适当的安全和健康应用和确定首次使用前调整限制的适用性。
2、术语2.1定义2.2.1铁素体——用从此之后铁素体这个词指α-Fe钢。
这包括马氏体、珠光体和所有其他非奥氏体钢。
2.2.2零塑性转变温度(NDT)——依据本试验方法规定标准落锤试样断裂的最大温度。
3、试验方法概要3.1落锤试验使用特殊准备的简支梁试样,试验前在试样的拉伸面产生一个材料裂纹。
试验是通过给定材料的一系列试样(通常4-8个)在系列选定温度下受单次冲击载荷以确定单试样断裂的最大温度。
冲击载荷由一个导向的,具有250-1200 fg-lbf(340-1630 J)能量的自由落体提供,能量依据钢的屈服强度来确定。
试样被阻止而弯曲大于几十英寸。
3.2通常的系列试验如下:在做好试样的温度条件准备后,初次落锤试验的试验温度由靠近NDT温度估算出。
依据第一次的试验结果,测试的其他试样在合适的温度间隔10°F(5℃)下操作。
材料的无延性转变温度
材料的无延性转变(NDT)温度是指按标准试样发生断裂的最高温度。
它表征含有小裂纹的钢材在动态加载屈服应力下发生脆断的最高温度。
TSG 21-2016里面称作无延性转变温度,GB/T 150-2011里面称作为无塑性转变温度。
1、我国标准无塑性转变(NDT)温度的确定GB 6803一86《铁素体钢的无塑性转变温度落锤试验方法》规定了试样的结构及尺寸,针对试样及试样材料的屈服限,规定了冲击功,也规定了试样冲击设备的结构尺寸等,在规定的冲击功落锤下,试样要发生本标准规定的断裂。
用一组试样按本标准规定的方法进行系列温度试验,测出试样断裂的最高温度。
在比该温度高5摄氏度时至少做两个试样,此两个试样均为未断裂,则将该试样断裂的最高温度确定为NDT温度。
2、美标规范的无塑性转变(NDT)温度的确定按ASTM E208-2017《铁素体钢无塑性转变温度落锤试验方法》3、我国的标准内容与ASTM基本一样,是依据人家的标准制定的。
比ASTM标准多3组辅助试样。
尺寸等,只是因英制单位折算成公制单位时小数的取舍问题,稍微规整了一点。
4、我们水压试验确定的温度是材料的无塑性转变(NDT)温度值,加60华氏度,折合加33摄氏度。
当然水压试验温度还考虑了材料厚度、焊接等诸多因素的影响。
名称:E208-95a(2000再认可)铁素体钢无塑性转变温度落锤试验方法本标准以固定名称e208出版;直接跟在名称后面的数字表示最初采纳的年份,假使修订,表示最近修订的年份。
在括号内的数字表示最近再认可的年份。
介绍由海军研究实验室发展而来在1952年的落锤试验方法已广泛使用于研究结构钢脆性断裂需要的起始条件。
落锤试验的设备已在好几个海军机构、研究机构和国内外的工业组织建立。
本方法用来做工业组织规范的目的和被用于好几个ASTM规范和ASTM锅炉和压力容器规范。
本程序确保试验操作在所有场合有共同的意义。
1、范围1.1本试验方法覆盖厚度大于等于5/8英寸(15.9mm)铁素体钢零塑性转变温度(DNT)的确定。
1.2本试验方法可以用于任何时候通过落锤试验方法确定常承受断裂韧性要求的钢的研究、协议、定购或规范状态。
1.3标准规定数值用英寸—磅单位。
1.4本标准不涉及所有安全地方,如果有,把它的用途联系在一起。
有责任使用该标准建立适当的安全和健康应用和确定首次使用前调整限制的适用性。
2、术语2.1定义2.2.1铁素体——用从此之后铁素体这个词指α-Fe钢。
这包括马氏体、珠光体和所有其他非奥氏体钢。
2.2.2零塑性转变温度(NDT)——依据本试验方法规定标准落锤试样断裂的最大温度。
3、试验方法概要3.1落锤试验使用特殊准备的简支梁试样,试验前在试样的拉伸面产生一个材料裂纹。
试验是通过给定材料的一系列试样(通常4-8个)在系列选定温度下受单次冲击载荷以确定单试样断裂的最大温度。
冲击载荷由一个导向的,具有250-1200 fg-lbf(340-1630 J)能量的自由落体提供,能量依据钢的屈服强度来确定。
试样被阻止而弯曲大于几十英寸。
3.2通常的系列试验如下:在做好试样的温度条件准备后,初次落锤试验的试验温度由靠近NDT温度估算出。
依据第一次的试验结果,测试的其他试样在合适的温度间隔10°F(5℃)下操作。
在系列最低不断裂温度下重复一次试验,以确定在此温度不断裂。
3.3在1984年,该方法用于焊接焊缝起裂,从双通过技术到目前单通过过程,在进行焊接修补焊接焊缝开裂是被禁止的。
对于钢的性能来说,易受到脆变温度的影响,零塑性转变温度可通过单通过焊接焊缝起裂获得,而不可通过使用早期的双通过焊接焊缝起裂获得或起裂焊波被修理过。
4、意义和使用4.1用于缺口条件下的铁素体钢的断裂强度转变受温度的显著影响。
对于一个给定“低”温度,缺陷(凹口)的尺寸和尖锐决定了要求脆性断裂开始的应力水平。
试验方法的意义是与建立温度有关,(这里定义为NDT温度),在“小裂纹”开始曲线,如图1,随着温度的降低落入正常的屈服强度水平,也就是那一点标记为NDT如图1.无显著特点的断裂分析图显示断裂起始小裂纹尺寸的大约范围在不同正常应力水平下,与NDT温度参考一样4.2起始断裂要求的其他条件可以用广义裂纹尺寸做出解释,应力-温度图如图1所示.该图来源于大量的试验,起裂和止裂测试,象与通过落锤试验建立的NDT温度相关一样。
NDT概念的确定已被相关大量的发生在船舶,压力容器,机械零件,锻件和铸钢使用中破坏的文献证实。
5.装置5.1落锤试验机是基于容易可用的钢结构产品而设计的。
落锤试验机的主要组成部件是一个垂直导向,自由落体和一个当堆焊道下落时提供给直角平面试样加载的固定砧座。
如图2说明了一个典型的落锤试验机的标准结构形状。
5.2固定于基础之上并处于垂直位置的导轨给重锤提供导向,重锤应该用合适的装置支撑,使与导轨接触,并确保它在单一垂直平面中下落。
重锤可以通过简便的方式提升。
重锤释放机理,功能类似于图2(b),应该使重锤自由下落没有影响并很快释放。
重锤应该由一块组成,或如果由几块组成,结构应牢固确保它冲击试样时作为一个单元动作。
重锤的冲击锤头应由半径为1英寸(25.4mm)、全断面最小硬度为50HRC的圆柱体钢。
重量应在50至300磅之间(22.7至136kg)。
导轨和提升装置应能提升重锤处于不同的固定位置并能获得250-1200ft-lbf(340 至1630J)的能量。
5.3 安装于导轨之下的水平基础应能保持标准试样要求的几种类型砧座的精确位置。
砧座导向应将终止台的中心线的砧座放在冲击锤头中心线之下。
总之,基座支撑导轨,但不是必需的。
基座安装于稳固的基础之上。
基础系统应足够牢固,确保以正常的落锤能量(表1)在NDT 温度以上使标准试样停止弯曲。
在测试过程中基座不应跳动或晃动,如有必要防止移动应确信基础可靠。
5.4防护栏类似于图2(c),它能阻止脆性钢断裂成两半时从设备中强有力的飞出。
5.5两块砧座的通用特征如图3。
砧座应依图4的尺寸做成。
砧座的支撑台和终止台应被钢硬化,它们的整个横断面的最小硬度达到50HRC ,在两个终止台之间确保留有试样上焊缝起裂的间隙。
如果要求,终止台可以由两个分离块组成。
砧座-基础系统应足够稳固以阻止正常落锤能量(表1)NDT温度之上使试样停止弯曲。
5.6测量系统应能保证每次试验重锤从任何想要得高度释放,限制在+10,-0%以内。
5.7图2显示的是装置的变体或落锤试验机的集成细节,允许提供装备功能的变体设备。
图5表示一个轻便的设计用于不同制作部位的压力容器组件的落锤试验。
6.注意6.1落锤试验用于测量大于等于5/8英寸(15.9mm)的结构材料的脆性起始特征。
本试验不推荐用于小于5/8英寸(15.9mm)厚的钢。
62本试验方法建立的标准试样和条件以确定给定钢的NDT温度。
在非标准测试条件使用标准试样或者使用非标准试样不应该用于规范的目的。
6.3本试验方法是在试样表面上使用一个小堆焊,其唯一目的是在试验过程中在试样的基体上提供一个小,分裂的缺口裂纹的起始脆性材料。
大量的材料特性表明焊接起裂的堆焊形成的热影响区比没有影响的平板区有更大的脆性阻力。
这种条件通过淬火和低温回火获得高硬度。
这个问题可以避免通过在淬火和回火热处理前在钢表面堆焊形成裂纹启动器。
除在冶金学术语之外,(例如,在热影响区形成一个塑性改善区的深加工钢的再结晶是可能的),热影响区的问题不会在常规晶粒珠光体结构钢或淬火和形成最大断裂韧度的高温回火钢中遇到。
7 测试样品7.1材料识别—所有取自给定板材、型材、铸件、锻件产品的样品材料和试样标识应与它们的母材信息(炉号、板号等)一致。
一个简单的鉴别系统应用来与获得所有潜在信息的详细说明表相结合。
7.2方向——落锤对试样的轧制和锻造方向敏感。
然而,除非经同意,来自买方的所有样品标识应方向相同,并应在报告中注明。
7.3与其他试样的关系——除非买方标识,试样应取自用来评价别的材料性能的其他类型试验位置的邻近位置(如力学测试试样)。
7.4锻造和铸造的特殊条件——锻件或铸件的落锤试验的样坯应从铸件、锻件的本体或本体的加长部位切取;也可从与产品同炉号、生产工艺相同而单独浇铸的坯料上切取。
坯料的厚度应与其最大壁厚相当。
完整固定于凸出垫或用于制作试样的延长部分的尺寸和位置应事先经过买方的同意。
如果锻件或铸件的设计不允许附上的测试样坯,应满足以下要求:7.4.1当产品尺寸相当并经过买方同意满足测试要求分离于锻件和铸件试样的尺寸与产品尺寸相当。
7.4.2如果供方能够证明于产品的化学成分、内部质量和冶金条件产品相当,试样可以组取自单独生产的测试样坯。
材料的加热和制造应与产品的条件一样。
试样切取的位置应事先得到买方的同意。
7.4.3特别地,在铸件要求X射线质量标准的情况下,单个的试样应该分开铸造,但与产品同时铸造。
不应使用冷铸。
测试样品应与铸件产品厚度T成正比,这里的T是该铸件任何注1:焊波的长度不是关键性的,在试样的中心提供一个裂纹开启的凹痕,当试样完全弯曲焊波不接触支撑装置。
7.5坯体尺寸——标准要求的测试样品的坯体尺寸如图6所示。
在±10°F(±5℃)以内,使用任何一种标准试样通过试验确定给定钢的的NDT温度同样重要的。
对于特殊厚度材料可以很方便可以选择图6所示的任何一种标准试样。
,并准备在第7部分加以描述此方法。
在标准测试条件获得的结果应按照确定NDT温度的要求做出。
7.6试样切割——材料试样和样品端部可以火焰切割。
试样边部应锯切或机加工,使用足够的冷却液防止过热,离任何切割面最小为1英寸。
产品比标准试样厚时,应从一边加工成标准试样,保持一个原制作表面,除非有别的规定或事先经过买方的同意。
在试验过程中保持的原制作表面应是试样的焊接(拉伸)面。
7.7起裂焊接——位于焊波中心位置的焊接起裂器大约2英寸长(如图6的WL)、1/2英寸宽(12.7mm),堆焊在落锤试样的原制作拉伸面应一次通过。
为了帮助焊接操作者正好堆焊在测试样品的中心,冲孔标记出图6的WL的大致尺寸,位置应如图7(a)的A和D。
与选择与冲孔标记不同,也可使用包含有中心夹缝的铜盘,1英寸*WL+1/2英寸(25mm*WL+13mm)如图7(b)。
焊接开始于点A或D,无中断的进行像一串焊波(无迂回)到另一点。
焊波的外观由电流、起弧电压和移动速度决定。
在合适条件下180到200A的电流,中等弧长和移动速度能产生一个适度的高密焊波。
堆焊起裂器的放大图如图7(c)所示。
对于P2和P3试样在焊接过程中推荐使用一个吸热装置,但并不要求这些小试样的微观结构变化最小。
7.7.1基体金属的微观结构——现在的数据表明堆焊的焊波能对特别在热处理钢确定NDT温度的焊接凹口下热影响区产生影响。
7.8焊接凹口——试样的最后准备是在堆焊的焊波长度的中心开缺口。
应小心确保只在堆焊层开缺口,切割工具不能接触试样表面。
缺口的切割可以使用薄砂轮,如图8所示,或者其他方便的切割工具如机械锯、弓锯等,或者放电去除加工。
焊接缺口的细节和典型的焊接缺口例子如图9所示。
7.9焊接缺口深度的测量——从焊接凸面起的缺口深度将随焊接凸面尺寸而变化。
由于留在试样表面的厚度和缺口底部不是标准化的,缺口的深度不能测量,如图9所示。
在试样上的焊接厚度应保持与允许的焊波外形差不多。
图10说明了一个测量焊接金属缺口底部厚度的任意调节的装置。
当显示器顶尖直接靠近接触缺口试样表面,可调节的刻度显示器置零。
然后放在焊接块上面用显示器的顶尖放在缺口底部直接测量焊接金属厚度。
在操作者准备几个试样获得经验后,仪器必须只是用于完成的缺口的最后检查。
7.10其他焊接起裂器——落锤试验的满意程度完成依赖于由焊接缺口发展而来的“起裂”条件。
示意图如图11,使裂缝开裂的试样的终止距离,D C,,值得注意小于可允许的砧座终止挠度D A, 标准厚度T,测试样品的合适跨距S。
仔细的准备和特殊的手握电极(在7.7中描述)已被成功的证明对所有高于大约400°F(200℃)温度起裂目的。