三代核电控制棒驱动机构钩爪钴基堆焊工艺研究

Study on hardfacing process of the latch with cobalt alloys about the third-generation nuclear power control rod drive mechanism

对三代核电驱动机构钩爪钴基堆焊焊接工艺进行研究,从材料可焊性、氧乙炔焊接方法、焊接火焰类型、焊接喷嘴尺寸、焊前预热等方面研究钩爪钴基堆焊焊接工艺,对堆焊层进行化学成分、金相组织、表面硬度等分析。结果显示:钴基堆焊采用氧乙炔堆焊,不同喷嘴直径和预热温度对堆焊层化学成分、硬度、金相组织均有影响;堆焊层组织主要是树枝晶,喷嘴直径越大,树枝晶越多,形成二次枝晶的几率越大;增加预热温度,堆焊层晶粒变粗,晶粒内析出相增加。

The hardfacing procedure of the latch with cobalt-base alloys about the third-generation nuclear power control rod drive mechanism is mainly studied from the aspects of the material weldability,oxyacetylene welding method,welding flame type,welding nozzle size and preheat.And the chemical composition,metallographic microstructure and surface hardness of the hardfacing layer are analyzed.The results show that the oxyacetylene surfacing are adopted as the welding method of hardfacing with cobalt-base alloys.The different nozzle diameters and preheating temperatures have an effect on the chemical composition,hardness and microstructure of the hardfacing layer.The main microstructure of the hardfacing layer is dendritic crystal.The larger nozzle diameters,the more dendritic crystal,the greater probability of secondary dendritic crystal formation.The grain size of hardfacing layer grows up and intragranular precipitation phase increases when the preheating temperature increases.