Q690CFD钢粗晶区再热脆化研究

Study on Reheat Embitterment in CGHAZ of Q690CFD

讨论了焊后热处理制度对Q690CFD钢粗晶区冲击韧性的影响，发现在500℃左右进行焊后热处理时粗晶区存在韧-脆转变点。金相、SEM及能谱分析结果表明，碳化物在原奥氏体晶界析出是导致韧-脆转变的原因。利用Thermo—Calc计算了碳化物的析出规律，优化了Q690CFD钢的焊后热处理工艺。

The effect of postweld heat treatment on the ductility of Q690CFD coarse grain zone is discussed in this article. The research results indicate that the point of 500℃ is brittle ductile transition temperature. According to the experimental results of metallurgical structure, SEM and energy spectrum, the carbide precipitation at original austenite grain boundary is the cause of ductile to brittle transition. The carbide precipitation regularity is calculated by Thermo-calc, and the postweld heat treatment process of Shougang＇s Q690CFD is optimized.