压水堆新型燃料组件骨架压力电阻点焊工艺研究

Process Research on Pressure Resistance Spot Welding Parameters for New Fuel Assembly Skeleton

压水堆新型燃料组件有别于AFA 3G型燃料组件,骨架采用导向管内外管“管中管”代替了AFA#3G型导向管缓冲段的新型设计,“管中管”与端部格架焊舌片采用压力电阻点焊工艺进行连接。通过对Zr4合金导向管外管单管段与焊舌片、导向管内外管双管段与焊舌片的点焊工艺进行分析,研究了焊接电流及电极压力对焊点剪切强度、熔核尺寸的影响规律。结果表明:Zr4合金薄壁管材两层及三层压力电阻焊时,焊接电流对熔核尺寸及剪切强度影响最大;随着焊接电极压力的增加,焊点的剪切强度和熔核尺寸均呈下降的趋势,但焊接压力的适当提高有利于形核的稳定性。

To be different from the AFA 3G fuel assembly,double guide tubes were used in the new design fuel assembly skeleton.The end grid tab was welded to the outer guide tube and the inner guide tube by using pressure resistance spot welding method.The spot welding technology of single pipe section and welding tongue piece,double pipe section and welding tongue piece of Zr4 alloy guide tube was analyzed,the effects of welding current and electrode force on the shear strength and nugget size of welding spot were studied.The results show when thin-walled pipe of Zr4 alloy was welded with two-layer and three-layer pressure resistance welding,the welding current has the greatest effect on welding shearing strength and nugget size.With the increasing of the welding electrode force,the shearing strength and nugget size of welding spot decreases,but the proper increase of the welding pressure is conducive to the stability of nucleation.