Wei LIU
材料科学技术（英文）
Transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) effects had been widely studied in single austenite steel. But in duplex γ & α(δ) phase, such as welding materials of stainless steel, they had been less studied. Tensile shear loading experiment of resistance spot welding specimens prepared with 2 mm 301L sheets, was carried out at 15℃ and -50℃. Optical microscopy and scanning electron microscopy (SEM) as well as X-ray diffraction (XRD) were used to investigate the microstructure of weld nugget, and specimens fracture surface. The results showed that the initial weld nugget was composed of 8.4% α(δ) ferrite and 91.6% austenite. Tensile shear load bearing capacity of spot welding specimen at -50℃ was 24.8 kN, 17.7% higher than that at 15℃. About 78.5 vol. pct. martensite transformation was induced by plastic deformation at -50℃, while about 67.9 vol. pct transformation induced at 15℃. The plasticity of spot welding joint decreased with the decline of experimental temperature.
关键词:
301L stainless steel
,
stainless
,
steel
,
Resistance
,
spot
,
wel
韩栋
,
李磊
,
毛小南
,
赵永庆
,
洪权
钛工业进展
Ti-2 Al-2.5 Zr合金焊丝的低倍组织中普遍存在细小坑痕形貌。为判定焊丝坑痕的缺陷性质，通过对显微组织和能谱成分的综合分析，初步判断钛合金焊丝低倍组织中出现的细小坑痕为金相腐蚀造成的腐蚀坑，再通过观察不同腐蚀时间的显微组织发现坑痕直径随着金相腐蚀时间增加而不断变大，从而验证了低倍坑痕为金相检验过程中的点腐蚀所致。 Ti-2 Al-2.5 Zr合金铸锭制备过程中不可避免地存在微区成分的差异，加上热加工过程中动态再结晶对成分的再分配效应，引发了材料局部微区成分及组织不均匀，这是金相腐蚀后呈现坑痕形貌的原因。由此可见，低倍组织中的腐蚀坑痕不属于冶金缺陷，不会影响钛合金焊丝的整体冶金质量和性能水平。
关键词:
钛合金焊丝
,
低倍检查
,
坑痕
,
腐蚀
