Abstract: Aiming at solving the problems in the welding process of AP1000 nuclear reactor coolant pump can in China, a laser welding technology with near-free-defect is proposed to achieve the good welding of Hastelloy C-276 which is used as the materials of the nuclear reactor coolant pump can. The effect of laser welding process on the microstructure is analyzed, and the tensile properties of weld joint at the different working temperature are evaluated. Also, by the electrochemical corrosion experiments of weld joint in acid, neutral and alkali solution, the corrosion resistance of weld joint is investigated. In addition, the welding deformation characteristics are calculated based on the finite element method, and the influence of transverse shrinkage distortion on the manufacturing accuracy is revealed. The results indicate that the pulse laser welding technology could achieve the good welding of Hastelloy C-276 without obvious welding defects. Under the condition of the can working temperature, the mechanical properties of welding joint is almost the same as that of base metal, which can guarantee the long using credibility. The corrosion resistances of the weld joint in the neutral and acidic conditions are better than those of base metal, which could improve the reliability of the weld joint. By the numerical simulation, it is found that the laser welding could cause the transverse shringkage distortion of the welding sample. But the distortion size is just 1/10 of the can manufacturing precision, so the welding precision completely satisfies the requirements of manufacturing precision of the nuclear reactor coolant pump can.

Key words: corrosion characteristic, Hastelloy C-276, laser welding, mechanical property, nuclear reactor coolant pump can, transverse shrinkage distortion