采用热模拟技术研究了12Cr1MoV钢焊接接头热影响区粗晶区中的再热脆化行为。结果表明: 再热温度对热影响区粗晶区的组织和性能有显著影响, 随再热温度的升高, 组织中的马氏体、贝氏体分解, 铁素体条合并, 碳化物析出量增多并聚集长大,冲击吸收能先降低后升高, 硬度变化则相反; 当再热温度为630 ℃时, 热影响区粗晶区的冲击吸收能达最低值, 而硬度达最高值, 材料发生再热脆化; 脆化的主要原因在于晶内碳化物的方向性析出以及在粗晶区晶界处大颗粒碳化物的出现。

The reheat embrittlement behavior of the coarse grain heat affected zone (CGHAZ) in welded joint of 12Cr1MoVG steel was investigated by means of thermal simulation technique. The results show that the reheat temperature had remarkable effects on the microstructure and properties of CGHAZ. With the increase of reheat temperature, the martensite and bainite in the microstructure decomposed while the ferrite merged, the precipitated carbides increased, gathered and grew up, and the impact energy first decreased and then increased, but the hardness displayed an opposite trend. At the reheat temperature of 630 ℃, the impact energy of CGHAZ had the lowest value but the microhardness hit the largest value, and the reheat embrittlement occured. The reheat embrittlement can be ascribed to the orientational precipitation of intragranular carbides and the occurrence of large granular carbides in the grain boundaries of CGHAZ.