高锰奥氏体超低温钢焊接接头的组织和力学性能
TIG Welding of High Manganese Austenitic Steel for Super Cryogenic Application
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摘要: 用金相、扫描电镜、X射线衍射仪及硬度测试、低温拉伸等方法研究了32Mn-7Cr-0.6Mo-0.3N奥氏体钢TIG焊接接头的组织及低温力学性能,结果表明,采用氮-氩混合气体保护的TIG焊接方法可获得满意的接头组织和性能。接头的金相组织致密、均匀,无裂纹、气孔等缺陷;77K温度拉伸断口为韧窝为主的韧性断裂特征。保护气氛中添加一定比例的氮气可有效抑制焊缝中氮含量的降低,保证较高的低温强度,77K温度下光滑试样的拉伸强度为1150 MPa。保护气氛中合适的氮气添加比例为4%。接头的组织稳定性很高,焊接前后的焊缝和热影响区以及低温拉伸试样断口变形区均保持全奥氏体组织。Abstract: In this paper,investigated the microstructure and cryogenic properties of TIG welding joints for 32Mn-7Cr-0.6Mo-0.3N austenitic steel by means of some methods such as metalography,scanning electron micro scope,X-ray diffractometer,hardness test,cryogenic tensile test and so on.The test results showed that the satisfied welded joints can be achieved using TIG welding of Argon and Nitrogen mixed protection.The joint microstructure is fine and homogeneous,and some welding defects such as crack and blowholes are not found.The 77 tensile fracture surfaces exhibit a tough character mainly composed of dimples.The decreasing of Nitrogen content in wended joints can be effectively suppressed by adding little Nitrogen into shielding gas,and better cryogenic strength of joint can be gained.The 77 tensile strength of smooth is about 1 150 MPa.The reasonable mixture rate of Nitrogen in shielded gas is 4%.The joint microstructure has high stability,and keep fully austenite phases in welds and HAZ after welding.
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Key words:
- high Manganese austenitic steel /
- TIG welding /
- joint microstructure /
- oryogenic property
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