焊后热处理对30CrMnSiNi2A钢电子束焊接件疲劳行为的影响

电子束局部热处理是一种新型的热处理方式，探讨其对电子束焊接接头组织和疲劳性能的影响规律具有十分重要的实际意义。文中采用CT(紧凑拉伸)试样，对30CrMnSiNi2A钢电子束焊接后焊态、焊后炉内整体热处理和电子束局部热处理三种焊接接头焊缝与母材的疲劳裂纹扩展速率进行试验研究；并测定上述两个部位的门槛值。结合金相组织分析，讨论焊后热处理对接头疲劳行为的影响。试验结果表明，电子束局部热处理和整体热处理都能够在一定程度上改善焊接接头的组织和近门槛值处抗疲劳裂纹扩展的能力。由于电子束局部热处理具有方便、省时、节省能源和提高生产率的优点，因而具有较大的应用潜力和研究价值。

EFFECTS OF POST HEAT TREATMENT ON FATIGUE CRACK BEHAVIOR OF ELECTRON-BEAM-WELDED 30CrMnSiNi2A STEEL

Generally, with a view to improve the microstructure and properties of the electron beam welded joint, the vacuum or furnace whole heat treatment (FWHT) should be considered after welding. The electron beam local heat treatment (EBLHT) is a newly heat treatment that provides the advantages of high precision, flexibility and efficiency, energy source saving and productivity improving. Therefore, it is very important to study its effect on microstructure and fatigue properties of electron beam welded joints. The fatigue crack growth rates of welds and base metals of three kinds of electron beam welded joints of 30CrMnSiNi2A steel have been analyzed using compact tension specimen. The joints studied are as-welded joints, joints after furnace heat treatment and joints after EBLHT. The threshold values in above two zones of each joint were also tested. The effects of Post-Weld Heat Treatment (PWHT) on fatigue behavior of joints were analyzed and discussed combined with metallurgical analysis. The results show that both EBLHT and FWHT can improve the microstructure and resistance to near threshold fatigue crack growth data of welded joints. Two possible mechanisms of fatigue properties improved by above two kinds of PWHTs have been revealed: (1) It is closely related to the microstructures of welds and base metals. (2) It is due to the residual stress relief effect and crack close effect. The advantages of convenience, speed, and energy saving give EBLHT big potential for the future and more research work needs to be done.