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采用焊接热模拟技术,参照实际焊接工艺,模拟中国低活化马氏体钢(CALM钢)热影响区粗晶区(CGHAZ)热循环过程,并对热模拟后试样进行不同的回火处理。实验发现,CLAM钢热模拟试样经回火处理,碳化物弥散析出,同样的回火条件下,CLAM钢显微组织差异不明显,回火前较高的热量输入导致回火后硬度值更低;在相同的热循环条件下,较高的回火温度会引起晶粒的显著长大,试样硬度值降低。热模拟试样在较高的温度下回火,可以更为有效地改善CGHAZ区域硬度,随回火的温度的继续升高,试样硬度趋于平稳。综合考虑回火工艺CALM钢硬度值以及晶粒度的影响,推荐回火温度为760～810℃。
The thermal cycling of CGHAZ in China heat-affected zone (CALM) steel was modeled by using welding heat simulation technology with reference to the actual welding process. The heat-treated samples were subjected to different tempering treatments. The experimental results show that the microstructure of the CLAM steel is not obviously different under the same tempering condition after the tempering of the CLAM steel thermal simulation specimen. The higher heat input before tempering results in the hardness value of the tempered steel being more Low; under the same thermal cycling conditions, higher tempering temperature will cause significant grain growth, sample hardness value decreases. The thermal simulation specimen tempering at a higher temperature can improve the CGHAZ hardness more effectively. With the tempering temperature continues to rise, the hardness of the sample tends to be stable. Considering the impact of CALM steel tempering hardness and grain size, the recommended tempering temperature is 760 ~ 810 ℃.