超低碳9Ni钢焊接接头低温韧性

针对新研制的通过淬火、中间淬火和回火处理工艺获得的超低碳9Ni钢,对其进行了实际焊接接头和模拟焊接热影响区低温韧性的研究.经-196℃低温夏比V形缺口冲击试验、金相显微观察、透射和扫描电镜分析.结果表明,单道焊粗晶区组织为粗大的板条状马氏体,低温冲击韧性较低.多道焊热影响区组织中,在马氏体板条间析出了逆转奥氏体,这种呈弥散分布的逆转奥氏体能细化晶粒、提高焊接热影响区的低温韧性.认为采用小热输入、多层焊、低的层间温度,可使焊接接头获得高的低温冲击韧性.

Low temperature toughness of ultra low-carbon 9Ni steel welded joints

This article investigates the low temperature toughness of welded joints and simulated HAZ of ultral low-carbon 9Ni steel which developed by quenching, intermediate quenching and tempering processed.The specimens were investigated by Charpy Vnotch impact test, optical microscope, TEM and SEM.The results show that the microstructure of lath martensite is coarsened and the low-temperature toughness is decreased in coarse grained HAZ of specimens single pass welding thermal cycled.The reversal austenite on boundaries of lath martensite appears in the dispersed distribution, and the grain will be fined, and low temperature toughness will be increased in HAZ of specimens multi-pass welding thermal cycled. It is desirable that low-heat input, multi-pass welding and low inter-pass temperature should be applied, which gives high low-temperature toughness of welded joints.