Study Of Laser Deposit Welding Technology On Cr13Mo1Si1V1 Cold-worked Mould

Mould plays an important role in modern industry, it directly determines the quality of the products, but the mould is easy to be worn during operating process and it greatly influences the life of dies. The methods usually used in mould repairing are surfacing with shielded metal arc welding process and spraying technology, they are difficult to ensure the life of mould. By means of the experiment using pulsed Nd:YAG laser repairing cold-worked mould, the systematic analyses on the optimization of parameters, the analysis of cladding defects and the repairing properties are carried out in this paper in order to provide the bases for practical application of the experiment results.Laser depositing is conducted by pulsed Nd:YAG laser welding process on the Cr13Mo1Si1V1 steel substrate using the laser weld-wire of 0.30mm and 0.50mm in diameter. Firstly, the pulsed laser autogenous welding is carried out to obtain the working range of the main parameters on a new mold material Cr13Mo1Si1V1 by the optimization of process parameters and the defect analysis, then the pulsed laser depositing procedure is designed. The best repair procedure is obtained by analyzing the pattern and the microstructure of build-up welding layer metals.Research results show that pulse energy and pulse width are key parameters of the ND: YAG laser welding process, they affect majorly depth and diameter of the weld; the pulse frequency and beam diameter are not obviously affect the size and weld cross section; beam diameter is just used to regulate the laser radiation area. The crystal crack appears accompanying with metal splash when the minor pulse width and beam diameter are chosen. The main metal microstructure of build-up weld layer is acicular martensite+ cryptocrystalline martensite+ tiny carbide+retained austenite and the main metal microstructure of HAZ is acicular martensite+ retained austenite+ carbide. When the power density is 0.29×106~0.31×106W/cm2 (including t=5.0ms,d=0.70mm), the spreading state and metallurgical bonding of bulk material are of good for the laser filler wire diameter d = 0.50 mm, the microstructure of build-up weld layer and HAZ are similar to the base metal's. Therefore, the power density of 0.29×106W/cm2(E=5.5J, t=5.0ms, f=11Hz, d=0.70mm) is the optimum repairing technology in this experimental conditions.