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裂纹缺陷严重影响大型锻件的合格率及使用寿命。为保证核电大型锻件质量、提高核电压力容器安全性,以加热温度、下压量以及保压时间为参数,采用预置裂纹方式对核电压力容器用钢SA508-3进行内部裂纹高温焊合实验研究。裂纹焊合效果采用金相显微镜、扫描电镜、能谱分析及力学性能实验等进行评价。结果显示,在高温短时间小变形情况下SA508-3材料内部裂纹均能焊合,裂纹焊合最低条件为:加热温度1100℃,变形量10%,保压时间15 s;焊合后试样强度值与基体相似,但塑性值有较大波动;根据扫描电镜及能谱分析确定,试样连接过程中带入的大量夹杂物是材料塑性指标波动较大的主要原因。
Crack defects seriously affect the large forging pass rate and service life. In order to ensure the quality of nuclear large forgings and improve the safety of nuclear pressure vessels, the internal cracking of SA508-3 for nuclear power pressure vessels was studied by the method of pre-cracking at high temperature, pressure and dwell time . The welding effect of the crack was evaluated by metallographic microscope, scanning electron microscope, energy spectrum analysis and mechanical property experiment. The results show that the internal crack of SA508-3 can be welded under the condition of small deformation at high temperature and short time. The minimum welding temperature is 1100 ℃, the deformation is 10% and the holding time is 15 s. The strength values are similar to the matrix, but the plasticity values fluctuate greatly. According to the SEM and EDS analysis, a large amount of inclusions are introduced during the sample connection, which is the main reason for the material plasticity index fluctuating greatly.