Effects of Scanning Strategies on the Distortion and Properties of Laser-Repaired Thin-Plate 2Cr13 Steel

In order to explore the effects of scanning strategies on the distortion and properties of laser-repaired thin-plate components, four commonly used strategies, including continuous raster scanning strategy, continuous orthogonal scanning strategy (COS), subarea W-type scanning strategy and subarea leap-type scanning strategy, were applied for laser-repairing thin-plate 2Cr13 steel. The finite element simulation and experimental results show that the temperature field of the laser-repaired layer prepared by COS exhibits symmetrical elliptical characteristic, with homogeneous temperature gradient along all directions. Consequently, the outermost of COS sample exhibits the smallest deformation of 2.86 mm, by avoiding both the unidirectional shrinkage of molten pool and the cumulative effect of longitudinal stress. In contrast, much larger distortion was produced by the other three scanning strategies due to the uneven temperature gradient. Dense martensite without defects was achieved by continuous scanning, while the coarsen martensite occurred by using subarea scanning. The repaired layer by using subarea scanning exhibits lower microhardness of 585-590 HV 0.2 and poor wear resistance of 1.45 × 10 −5 –1.48 × 10 −5 mm 3 /N m, in comparison to 613–618 HV 0.2 and 0.9 × 10 −5 –0.92 × 10 −5 mm 3 /N m obtained by using continuous strategy. COS is the most ideal strategy in laser-repairing thin-plate 2Cr13 steel in this work, exhibiting the lowest distortion as well as the highest microhardness and wear resistance.