Optimization and wear behaviors of 316L stainless steel laser cladding on rail material

Abstract

Laser cladding is a potential technology for repairing the rail with side wear. The laser processing parameters should be optimized and the wear behaviors of clads should be analyzed before its application. Therefore, single-pass and multi-pass laser cladding experiments of 316L stainless steel powder with different laser powers, scan speeds, scan modes (directions), and numbers of layers are conducted on the U71Mn rail to optimize the processing parameters. After that, sliding wear tests are conducted on different depths in clad to explore the wear behaviors. The results show that with the increase in laser power, the clad width is increased, the height is increased first and then decreased. With the increase in scan speed, both the clad height and width are decreased. Scan mode 1# produces the thinnest clads, the mode 3 produces the thickest ones. The microstructure of clad is composed of dendritic grains. With the increase in depth in clad, the grain size decreases and the hardness increases. The grain size is increased with laser power and decreased with scan speed, and the hardness is increased with the power and speed. Smallest grains and highest hardness are produced using mode 1#, and largest grains and lowest hardness using mode 3#. The Cr and Ni elements from clad permeate into the heat affected zone of U71Mn rail material. Wear depth of clad has a positive relationship with the grain size and a negative relationship with the post hardness. A wear resistance coefficient, Xphv2.55/Xgs1.56,where Xphv refers to the post hardness and Xgs refers to the grain size, is proposed to characterize the inherent anti-wear property of 316L stainless steel clad on U71Mn rail.