热处理对低活马氏体钢焊接热影响区的影响

Effects of Heat Treatment on CLAM Steel Welding Heat Affected Zone

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℃。

Referring to the actual welding process,the thermal simulation technique was used for simulating the thermal cycling of the coarse grained heat affect zone（CGHAZ） of CLAM steel,and then different tempering treatments were preceded on the samples after simulation.Dispersed precipitation of the carbide is found after the tempering treatment.In the same tempering condition,no obvious differences of microstructure was observed among the tested samples;higher heat input before tempering resulted in lower hardness after tempering.In the same thermal cycling condition,higher tempering temperature lead to remarkable increase of grain size and decrease of hardness.The hardness of CGHAZ can be effectively improved by tempering the simulated samples at higher temperature and then it changes to be steady with the continue increasing of temperature.Based on the comprehensive consideration of the effect of tempering process on both the hardness and the grain size of CLAM steel,the tempering temperature is advised to be 760℃～810℃.