张忠伟
,
白青山
,
王建军
,
张维
,
高俊
,
乔岩欣
腐蚀学报（英文）
某国产600MW核电机组在停堆检修过程中, 发现位于汽轮机高压缸主蒸汽入口主调门油动机活塞杆已经断裂. 通过分析活塞杆的材料、显微组织、力学性能和断口等, 并结合活塞杆制造的资料等信息, 分析了造成活塞杆断裂的原因.
关键词:
核电
,
steam turbine
,
connected rod
,
brittle fracture
赵杰
,
迟成宇
,
程从前
金属学报
研究了Sn-3Ag-0.5Cu-xBi(x=0, 1, 3)/Cu钎焊接头在140和195℃时效过程中的剪切强度变化. 结果表明: 随着时效时间的增加, 界面金属间化合物(IMC)层的厚度逐渐增加; 140℃时效时, Sn-3Ag-0.5Cu接头的剪切强度随时效时间延长变化不大, Bi元素的添加提高了钎焊接头的剪切强度;195℃时效时, 钎焊接头剪切强度均随时效时间延长而下降, Bi元素的添加对接头剪切强度的影响不明显. 剪切断口分析表明: 随着界面化合物层厚度的增加,断裂机制逐渐由韧性断裂变为脆性断裂, 较高剪切强度对应于钎料基体的韧性断裂, 而低剪切强度对应于钎料与界面化合物层之间的脆性断裂.
关键词:
Sn-3Ag-0.5Cu-Bi
,
shear strength
,
ductile fracture
,
brittle fracture
Liangyun LAN
金属学报(英文版)
Thermomechanical process and tempering heat treatment were employed to produce the experimental steel plates. The effect of boron addition on the microstructure and mechanical properties of low carbon bainitic steels was studied in this paper. Microstructure observation and crystallographic features were conducted by using optical microscopy, SEM, TEM and electron back scattering diffraction (EBSD) analysis. The results showed that under the same rolling processes and heat treatment conditions, a substantial increase in strength is obtained by addition of boron into steel, but accompanied by an obvious drop in toughness. New martensite phase forms along the grain boundaries on tempering at 650 ℃ mainly due to boron segregation, which can further deteriorate impact toughness of the boron bearing steel. The EBSD analysis showed that high angle grain boundary is not responsible for the deteriorated toughness of the boron bearing steel because it has relatively higher percentage of high angle grain boundary than the boron free steel. The low toughness of the boron bearing steel is mainly attributed to the coarse boride precipitated particles according to the results of fractograph observation.
关键词:
Low carbon bainitic steel
H. Y. Jing
,
L. X. Huo
,
Y. F. Zhang and F. Minami( 1) College of Material Science
,
Tianjin University
,
Tianjin 300072
,
China 2) Osaka University
,
Japan)
金属学报(英文版)
A computation framework for brittle fracture which incorporates weakest link statistics and a microme- chanics model reflecting reflecting local damage of the material is described.The Weibull stress W emerges as a probabilistic fracture parameter to define the condition leading material failure. Unstable crack propa- gation occurs at a critical value of W which may be attained paior to or following some amount of duc- tile crack extension. A realistic model of ductile crack growth using the computation cell methodology is used to define the evolution of near tip stress fields during crack extension. An application of proposed framework to predict the measured geometry and ductile tearing effects on the statistical distributio of fracture toughness for the pipe line steel welded joint is described.
关键词:
fracture toughness
,
null
,
null
师周龙
,
邵成伟
,
惠卫军
,
张英建
,
徐乐
,
项金钟
钢铁研究学报
对国内新开发的的胀断连杆用非调质钢36 MnVS4性能进行了研究,结果表明,材料的显微组织为极细的铁素体+珠光体混合组织,钒等微合金化元素的加入使得晶粒更加细化;胀断结果显示,材料断口为典型的脆性解理断裂,胀断变形量很小,达到或超过传统C70S6胀断效果;碳含量的降低引起组织变化,改善了切削加工性能;材料的强度增加,屈强比也显著提高,对连杆的轻量化设计和可靠性有显著的意义,可以用于胀断连杆.
关键词:
胀断
,
连杆
,
非调质钢36MnVS4
,
脆性断裂
,
显微组织
孙莹
,
于庆波
材料热处理学报
以X60和X70管线钢为研究对象,研究了管线钢中显微组织与断裂韧性之间的关系.结果表明,多边形铁素体对管线钢既有增韧性又有减韧性作用:当钢中分布细小的多边形铁素体晶粒时,多边形铁素体迫使裂纹分叉、弯曲和转向,导致裂纹的扩展功提高,增加了管线钢的韧性,而且随多边形铁素体含量增多,落锤撕裂试验断口纤维率也随之提高.然而,当多边形铁素体晶粒粗大且以绝对多的数量分布在基体中时,其增韧性作用消失.
关键词:
多边形铁素体
,
脆性断裂
,
断口纤维率
,
落锤撕裂实验
马小明
,
黄永敏
机械工程材料
采用宏观检验、扫描电镜观察、化学成分分析、显微组织观察和力学性能测试等方法对断裂失效的石脑油管线承插焊接管进行了理化检验,并分析了失效原因.结果表明:承插焊接管断裂为脆性断裂,失效的主要原因是承插焊接的工艺不当,导致焊缝熔合线附近存在微观裂纹、焊缝热影响区晶粒粗大、焊接残余应力水平较高.最后提出了严格控制焊接及后续热处理工艺的措施.
关键词:
石脑油管
,
承插焊接
,
脆性断裂
,
失效分析
