610 MPa级水电用钢再热脆化研究

A Study on Reheat Embitterment in CGHAZ of 610 MPa Hydroelectricity Steel

讨论了焊后热处理制度对不同热输入下610MPa级水电钢粗晶热影响区冲击韧性的影响，发现当热输入为30kJ／cm时在620℃附近有脆化倾向；当热输入为40kJ／cm时在580℃出现显著再热脆化。SEM、TEM及能谱试验结果表明，碳化物在原奥氏体晶界析出是发生再热脆化的原因。焊接热输入不同导致碳化物在焊后热处理时溶解规律不同，从而造成了40kJ／cm焊接热输入下发生再热脆化的温度较30kJ／cm焊接热输入下再热脆化温度向低温方向移动。根据试验结果优化了610MPa水电钢焊后热处理工艺。

The influence of postweld heat treatment regime to the impact ductility of 610 MPa hydroelectricity steel＇s coarse grain heat affect zone （GHAZ） is discussed in the article. The research results indicated that while heat input is 30 kJ/cm, the point of 620℃ was brittle ductile transition temperature ; while heat input is 40 kJ/cm, the point of 580 ℃ was obvious brittle ductile transition temperature. According to the experimental results of SEM, TEM and energy spectrum, the carbide precipitation at original austenite grain boundary resulted in the brittle ductile transition. The different dissolving regularity resulted from different heat input. Consequently, reheat embitterment temperature while heat input is 40 kJ/cm was inclined to move to lower temperature, compared with reheat embitterment temperature while heat input is 30 kJ/cm. According to research results, the postweld heat treatment regime of 610 MPa hydroelectricity steel was optimized