The shape of the claws of the control rod drive mechanism（CRDM） is complex and precise

the claws are the motion actuator in primary circuit of the pressurized water reactor

the surfacing layer of the pin hole and claws tooth is welded by the cobalt-base alloys

so the microstructure and properties of the surfacing layer have a great influence on the CRDM. The appropriate technological parameters that meet the design requirements are obtained by the oxyacetylene welding technology and laser welding technology tests.In addition

the microstructure characterization and analysis of the surfacing deposition layers of the cobalt-base alloys obtained by theses two welding technologies are carried out

the differences of the macrostructures and microstructures of the deposition layers of these two technologies are compared

and the micro hardness of the deposition layer is tested are contrastively analyzed. The elements Co

Cr and Fe of the deposition layer are tested by the line scanning. The relations between the dilution rate and hardness difference of these two different deposition layers are analyzed through the distribution of element Fe. No micro crack

inclusion

air hole

lack of fusionand other defects are observed in these two different surfacing layers. Because of the fine grain strengthening effect

the grain in the surfacing layer of cobalt-base alloys by laser welding is the most fine

and the micro hardness is also the highest in the surfacing layer.