Tearing Toughness of Ductile Metals

A new parameter, i.e., tearing toughness, was employed to characterize the mechanical properties of some ductile metals(Cu, Cu–2 wt% Be, Cu–Al alloys, and some steels) by using three-leg trousers tearing tests. The experimental results demonstrate that their tearing toughness is not a physical constant and shows a close relationship with the materials' types and microstructures. It can be inferred that the tearing toughness of different ductile metals has their respective variation range, expectantly, and may be represented by the comprehensive mechanical properties of strength and ductility for various ductile materials.     

550 MPa级焊缝金属冲击韧性研究

采用冲击试验研究了-40～20℃温度范围内550MPa级手工焊条电弧焊焊缝金属冲击韧性,利用金相显微镜、扫描电镜表征了焊缝金属的显微组织与断口形貌.结果表明,焊缝金属显微组织由先共析铁素体和针状铁索体构成.焊缝金属冲击功随着测试温度的降低而减小,冲击断口中塑性区域所占面积也相应减少.添加Ni、Mo元素,降低Mn、Si含量的焊缝金属在所测试温度范围内具有更高的冲击韧性.     

低温高韧性球墨铸铁件生产过程的韧性控制

分析了球墨铸铁件低温冲击韧性的影响因素,探讨了生产过程中控制低温韧性的方法。通过调整熔炼原材料及热处理工艺的试验验证,指出铁液冶金质量、球化孕育处理和热处理工艺的控制是生产低温高韧性球墨铸铁件的关键。     

Effect of Trace Element on Microstructure and Fracture Toughness of Weld Metal

The microstructure and fracture toughness of weld metal under Ti-free and Ti-containing different fluxes were investigated in this study.It was found that the trace element Ti of flux in submerged arc welding produced significant influence on the fracture toughness.The addition of 60 ppm Ti induced the sharp increase in J_(0.2) value from 232.78 to 364.08 kJ/m~2.Microstructure characterization revealed that a large number of oxide inclusions prompted the nucleation of acicular ferrites and refined grains,which improved the fracture toughness of Ti-containing weld metal greatly.Moreover,the crack propagation path was more tortuous and bifurcated due to the small amount of carbide precipitations along grain boundaries and blocky martensite-austenite islands for Ti-containing weld metal.Meanwhile,the large-angle grain boundaries caused crack deflection and increased the resistance of crack propagation compared to Ti-free weld metal.     

X65管线钢焊缝金属断裂韧度的统计分布

基于焊接制造过程的影响，焊缝的断裂韧度具有本质的变异性。文中进行X65管线钢焊缝断裂韧度测定试验。建立确定断裂韧度统计分布模型，经多种数理统计检验，对断裂韧度指标δc的统计分布函数进行了统计拟合检验。统计结果表明威布尔分布函数是描述断裂韧度指标δc的最佳拟合分布函数。     

锆对X70钢焊缝微观组织及韧性的影响

通过在埋弧焊焊剂中添加铁锆合金粉末，以此向焊缝金属过渡锆元素，研究了金属锆对X70钢焊缝金属微观组织和性能的影响。结果表明，锆的加入增加了焊缝金属中针状铁素体的含量，改善了焊缝金属的微观组织。夏比冲击韧性试验显示，锆含量在0．006％时焊缝金属韧性最好。超过0．006％，焊缝金属中虽然也保持了较高的铁素体含量，但由于出现了小岛状的M-A组元，导致韧性降低。     

低温高韧性球墨铸铁特点及韧性控制因素

低温高韧性球墨铸铁的需求日益增长,然而其生产技术及质量控制有较大难度。本文主要内容：低温高韧性球墨铸铁的性能特点及相关标准,低温断裂的特征及其表征方法,组织及主要成分对其冲击性能的影响规律等。     

消除应力退火对STE355钢焊接热影响区韧性的影响

采用焊接热模拟方法研究了不同温度退火时热影响区韧性的变化。试验结果表明，退火温度为５００℃时，单次热循环热影响区动性显著上升，而多次热循环热影响区韧性略有下降。退火温度进一步升高时，前者韧性急剧下降，而后者变化不大。     

试样缺口组织对P92钢焊缝冲击功的影响

根据对P92钢进行焊接工艺评定时出现的焊缝冲击韧性问题,从标准V型冲击试样的缺口组织方面研究了P92钢焊缝冲击韧性.结果表明,P92钢焊缝冲击韧性随焊缝柱状晶与V型缺口角度的增加而增加,缺口尖端组织晶粒的大小对其焊缝冲击韧性有重要影响.     

T91/10CrMo910焊接接头韧性分析

采用硬度试验、示波冲击试验、SEM断口分析、金相组织分析等,对电厂服役一年的T91/10CrMo910焊接接头的冲击韧性进行了分析。结果表明:焊缝区为准解理型脆性破断;10CrMo910热影响区和T91热影响区为微孔聚合韧窝型韧性破断。焊缝区组织为粗大的板条马氏体,并且焊后回火不充分,韧性差;10CrMo910热影响区和T91热影响区的组织分别为索氏体和细的回火马氏体,韧性较好。示波冲击曲线与断口形貌和硬度以及组织有良好的对应关系,是韧性分析的有效方法之一。     

水轮机叶片焊缝及其热影响区裂纹分析

水轮机叶片上的焊缝及其热影响区常发现有穿透性的裂纹,微观分析结果表明焊缝中存在夹杂物在焊接残余应力、工作应力、机械震动应力和电化学腐蚀的共同作用下,造成水轮机叶片的焊缝及其热影响区形成穿透性的腐蚀疲劳裂纹。     

2009年原生及再生铂族金属市场

2008年9月以来，全球金融危机导致全球铝价格大跌，铂族金属也在这一跌势中受到重创，铂金属2009年2月价格为每克26．46美元，比2008年3月的81．13美元下跌了67％，钯金属价格每克5．64美元，同比下跌73％，铑金属更是在半年内由超过每克352.74美元的创纪录高价下跌了90％。另一个受到严重打击的行业是汽车催化剂转换器的回收。     

纳米稀土氧化物对铁粉焊条焊缝低温冲击韧度的影响

在碱性铁粉焊条药皮中添加不同量的纳米稀土氧化物粉体.对焊缝进行扩散氢含量、低温冲击及化学成分的测试和分析.结果表明:适量的纳米稀土氧化物粉体可有效降低熔敷金属中扩散氢及硫、磷的含量,并能显著提高焊缝金属的低温冲击韧度.     

2009年原生及再生铂族金属市场

2008年9月以来,全球金融危机导致全球铝价格大跌,铂族金属也在这一跌势中受到重创,铂金属2009年2月价格为每克26.46美元,比2008年3月的81.13美元下跌了67%,钯金属价格每克5.64美元,同比下跌73%,铑金属更是在半年内由超过每克352.74美元的创纪录高价下跌了90%.另一个受到严重打击的行业是汽车催化剂转换器的回收.     

X80厚壁管线钢不同焊接速度下焊缝韧性研究

采用西气东输二线用X80 18.4mm壁厚管线钢,匹配BG-H06H1焊丝和BGSJ101-H1焊剂,研究了不同焊接速度下焊缝的外观形貌和组织性能.结果表明,在不同焊速下,焊缝成型好,表面光滑,焊缝抗拉强度均在720MPa以上,硬度小于276HV10;在焊速为1.6～1.8m/min时,焊缝冲击功稳定,-20℃下平均值可达136～176 J;在1.4～1.5m/min时,冲击功出现波动,最低45J.针对低速下焊缝韧性的波动,采用光镜、SEM等对焊缝微观组织变化、冲击断口形貌、成分偏析、板材及焊材纯净度等进行了分析.研究结果表明,焊缝原始奥氏体晶粒大小对韧性有显著影响;晶界AlN、硫化物析出是形成焊缝光滑脆性断口的主要原因;焊接线能量过大或过小,以及焊缝中高熔点氧化物夹杂均会引起冲击值下降.     

低碳高锰HFW钢管焊缝冲击韧性的优化研究

采用化学分析、力学性能测试、光学金相观察、扫描电镜观察等手段,对低碳高锰HFW钢管进行检测和评价,并对韧性较差的焊缝冲击试样进行分析。结果发现,由于靠近焊缝且平行于焊缝的金属流线中Mn的偏析,造成金属流线上形成沿着焊缝方向分布的马氏体,从而降低了焊缝的冲击韧性。通过后续对低碳高锰HFW钢管进行退火热处理,消除了焊缝组织中的马氏体脆性相,有效改善了焊缝冲击韧性。     

Effect of Nickel Contents on the Microstructure and Mechanical Properties for Low-Carbon Bainitic Weld Metals

Multi-pass weld metals were deposited on Q345 base steel using metal powder-flux-cored wire with various Ni contents to investigate the effects of the Ni content on the weld microstructure and property. The types of the microstructures were identified by optical microscope, scanning electron microscope, transmission electron microscope, and micro-hardness tests. As a focusing point, the lath bainite and lath martensite were distinguished by their compositions, morphologies, and hardness. In particular, a number of black plane facets appearing between lath bainite or lath martensite packets were characterized by laser scanning confocal microscope. The results indicated that with the increase in Ni contents in the range of 0, 2, 4, and 6%, the microstructures in the weld-deposited metal were changed from the domination of the granular bainite to the majority of the lath bainite and/or the lath martensite and the micro-hardness of the weld-deposited metal increased. Meanwhile, the average width of columnar grain displays a decreasing trend and prior austenite grain size decreases while increases with higher Ni content above 4%. Yield strength and ultimate tensile strength decrease, while the reduction in fracture area increases with the decreasing Ni mass fraction and the increasing test temperature, respectively. And poor yield strength in Ni6 specimen can be attributed to elements segregation caused by weld defect. Finally, micro-hardness distribution in correspondence with specimens presents as a style of cloud-map.