12Cr1MoV钢硬度超标焊缝的组织性能研究及原因分析

Microstructure and Mechanical Properties of 12Cr1MoV Steel Welded Joint with Excessive Hardness and Cause Analysis

通过力学性能测试、金相组织检验及扫描电子显微镜观察等分析了某火力发电机组12Cr1MoV钢硬度超标焊缝的显微组织和力学性能。试验研究结果表明:12Cr1MoV钢硬度超标焊缝的强度高、塑性低、冲击韧性较差;焊缝硬度超标是由于焊后热处理恒温温度不足所致;焊缝硬度超标会使该材料焊接接头产生再热裂纹的倾向增大,容易出现早期开裂失效;采用较小的焊接热输入、有效的焊后热处理、减少接头部位的应力集中是减少12Cr1MoV钢焊接接头再热裂纹的有效措施。

The microstructure and mechanical properties of the 12Cr1 MoV steel weld with excessive hardness of a thermal power unit were analyzed by mechanical property test, metallographic structure examination and scanning electron microscopy observation. The experimental results show that the 12Cr1 MoV steel weld with hardness exceeding standard has high strength, low plasticity and poor impact toughness. The excessive hardness of the weld is due to insufficient constant temperature of post-weld heat treatment. The excessive hardness of the weld increases the tendency of reheating crack, early cracking failure is easy to occur. Using small welding heat input, adopting effective heat treatment and reducing stress concentration of the joint are effective measures to reduce welding reheating crack of the12Cr1 MoV steel joint.