核电压力容器SA508-3钢内部裂纹高温焊合实验

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。

Bonding experiment of internal crack at high temperature for nuclear pressure vessels steel SA508-3

Crack defects seriously affect the qualification rate and service life of heavy forgings.In order to ensure the quality of heavy forgings and improve the safety of nuclear pressure vessels,an experimental study on bonding process of nuclear pressure vessels steel SA508-3 was performed by pre-existing crack with the parameters of heating temperature,displacement under pressure and pressure holding time.Then,the bonding effect of crack was evaluated by metallographic microscope,scanning electron microscope,energy spectrum analysis and mechanical property tests.The results show that all of internal cracks of material SA508-3 can be bonded in the case of small deformation,high temperature and short pressure holding time.Furthermore,its suitable condition is with small deformation of 10%,high temperature of 1100 ℃ and short pressure holding time of 15 s respectively.However,the strength of samples after bonding is similar to that of original material,but the plasticity has a heavy fluctuation coming from the impurities in the process of sample bonding which is confirmed by scanning electron microscope and energy spectrum analysis.