Research On The Repairing Process Of Laser Surfacing Welding Of High Strength Requirement

Laser surfacing welding is a process that clads certain thickness materials that have special properties on the metal surface with the theory of surfacing welding, it has became the research hotspot at home and abroad in recent years. Now the application of the large-scale and high-strength materials is mostly focused on adverse working environment such as long-time, heavy-load, terrible corrosion etc., and in this case, crack, wear and fatigue failure always happen on the surface of the materials. And Laser surfacing welding repairing process can prolong the service life of the parts, save the cost and improve the production efficiency. At present, research on the repairing process of laser surfacing welding of high-strength requirement materials is rarely in the world. In this paper, the laser surfacing welding repairing process aimed at high-strength requirement materials witch work under the adverse working environment was studied.Firstly, a FEA model of parameterized laser surfacing welding was built,the influence on the microstructure of surfacing layers caused by temperature field, the surfacing layer temperature field and temperature-time history of layers` nodes was studied, and the temperature gradient of different positions, the influence on the temperature gradient and the cooling rate coursed by different process parameters was also studied. The optimum technological parameters selection method base on the substrate penetration has been found and experiments have been done to demonstrate the validity of this method.For evaluating the effect of the laser surfacing welding, experiments have been done. The DLF-301 of high-strength material was welded on the substrate of 34CrNi3Mo using the optimum technological parameters based on the simulation and experimental verification, meanwhile the same welding processing has been done by using the manual arc surfacing welding. Compare the microstructure and performance of the surfacing layer and heat affected zone produced by the two processing means, the result showed that: the laser surfacing welding has low dilution rate and unitary fusion zone tissue, the heat affected zone is also smaller, the hardness, strength, toughness of the tissues is much higher than the manual arc surfacing welding, the multiple layer surfacing interface is significant, and the stress is much lower too.To sum up, laser surfacing welding technology has provided an efficient way for high-strength work-piece to recover its shape and repair its function in adverse working environment. It is of great importance in terms of prolonging the life expectancy of work-piece, reducing the remanufacturing cost and realizing the reusing of resource and sustainable development.