极限模焊工况下大厚度SA387Gr11CL2钢板的力学性能

Mechanical properties of large thickness SA387Gr11CL2 steel plate under the condition of limit PWHT

针对设计院和制造厂提出的越来越严格的模焊工艺要求,结合136 mm厚钢板研究了极限模焊工况对大厚度SA387Gr11CL2钢力学性能的影响。结果表明,在保温温度690℃、保温时间24h、装出炉温度200℃、升降温速率30℃/h的极严格模焊工艺制度下,钢的全厚度(表面下1.6 mm、板厚1/4处及板厚1/2处)室温拉伸性能尚可,但0℃及以下随着冲击温度的降低,相应冲击吸收能量逐渐下降,板厚1/2处-20℃冲击吸收能量已经接近标准要求的下限,富余量很小,结合金相和扫描电镜进行组织分析,表明过分加严模焊工艺会引起显微组织中碳化物沿晶界偏聚并长大,使钢板韧性明显变差。

According to the more strict requirements of PWHT put forward by the design institute and the manufacturer,the influence of the limit PWHT condition on the mechanical properties was studied with 136 mm thickness SA387 Gr11 CL2 steel plate.The results show that the tensile properties of the steel with full thickness(1.6 mm under the surface,1/4 of plate thickness and 1/2 of plate thickness)at room temperature are still acceptable.However,at 0℃and below,the corresponding impact absorbed energy decreases gradually with the decrease of impact temperature.The-20℃impact absorbed energy at 1/2 of the plate thickness has reached the lower limit of the standard requirements,and the surplus is not enough.The microstructure analysis combined with metallography and SEM shows that the carbide in the microstructure will segregate and grow along the grain boundary due to excessive rigor PWHT,resulting in obviously worse toughness of the steel plate.