成形工艺对奥氏体不锈钢焊接接头超低温冲击韧性影响的试验研究

Influence of Plastic Deformation on Impact Toughness of Austenitic Stainless Steel Welding Joint at Ultra-Low Temperature

主要采用夏比V型缺口示波冲击试验、X衍射分析(XRD)等方法研究了塑性变形和焊接对304和304L奥氏体不锈钢焊接接头超低温冲击韧性的影响,并探究了冲击吸收能量与侧向膨胀量之间的关系。结果表明:材料的冲击吸收能量和侧向膨胀量都随着变形率的增加而降低,塑性变形消耗的塑性功与冲击吸收能量的下降趋势相近,裂纹扩展功较小且基本不变。两种材料的塑性变形都诱发了马氏体相变,产物为ε和α'马氏体。焊接降低塑性功的同时,也会引起裂纹扩展功的下降。母材和热影响区的冲击吸收能量和侧向膨胀量近似呈线性关系,焊接对此线性关系影响不明显。冲击吸收能量和侧向膨胀量均可作为超低温容器合格判定指标。

The influence of plastic deformation and welding on the ultra-low temperature impact toughness of 304 and 304L austenitic stainless steel welded joints was investigated by using Charpy V-notch impact test, X-ray diffraction. The paper also explored the relationship between the impact absorbed energy and the lateral expansion. The results showed that both of the material＇s impact absorbed energy and lateral expansion decreased with increasing of the deformation rate. The plastic energy consumed by the plastic deformation showed a similar trend with the impact absorbed energy, and the crack propagation energy was small and stayed unchanged basically. The plastic deformation of 304 and 304L stainless steel induced martensitic transformation to generate martensitic of ε and α＇. The welding not only decreased the plastic energy but also reduced the crack propagation energy. There was a similar linear relationship between im- pact absorbed energy of base metal and heat affected zone, in addition the welding had no obvious influ- ence on the linear relationship. Both of impact absorbed energy and lateral expansion can be a decision in-dex to judge the uhra-low temperature vessels qualified.