Evaluation of oblique laser shock peening effect of FGH95 superalloy turbine disk material

Abstract

There are many influence factors and characterization indexes for the processing effect of laser shock peening (LSP) on metal materials, and the influence mechanism is complex. The FGH95 superalloy used for turbine disk manufacturing was taken as the research object in this paper. Taking the laser energy, beam diameter and the number of impacts as test factors, the three-factor and the three-level orthogonal experiment was carried out by taking 4 J, 6 J, 8 J laser energy, 3 mm, 4 mm, 5 mm beam diameter, one, two and three times of impacts， respectively. The nine characterization indexes data were obtained by test instruments and equipment, such as residual stress, microhardness and surface roughness. The coalitional game method and gray relational improved TOPSIS method were used to establish an evaluation index system of oblique laser shock peening (OLSP) effect to explore the influence of laser processing parameters on material properties. The results show that the evaluation method and index system are highly feasible and can be used to evaluate and compare the strengthening effect of different processing samples efficiently, comprehensively and scientifically. When the laser energy is 8 J, the beam diameter is 3 mm and the number of impacts is 3, the gray correlation relative closeness degree is 0.7869, with the relatively best strengthening effect for the FGH95 superalloy. Under the index weight set in this paper, the comprehensive material properties of the FGH95 superalloy is improved by 3.72 times compared with the unimpacted sample. Based on the sample data evaluated, when the laser energy of 6 ~ 7.5 J, 2 or 3 impacts, the beam diameter of 4 ~ 5 mm, the comprehensive material properties of FGH95 superalloy after LSP are close to the comprehensive material properties obtained by the relatively optimal process parameters. Therefore, under the premise of ensuring the quality of strengthening, from the consideration of cost and timeliness, the process parameters with slightly lower laser energy and fewer impact times can be selected. The evaluation index system has essential reference significance for reducing the experimental workload, saving the experimental cost, and promoting and applying laser impact processing technology.