Laser surface melting of a complex high alloy steel

• Laser surface melting (LSM) has produced refinement of a complex high alloy steel.
• The interdendritic spacing, λ, was controlled by the depth of melt penetration.
• The microhardness in the LSM region decreased linearly with λ-0.5.

The effect of laser surface melting (LSM) on the microscopic morphology of a complex high alloy steel has been examined in single track experiments. Different combinations of power (1–4 kW) and scan speed (500–1000 mm min−1) were selected in order to obtain a range of depths of melt penetration. An increase in the depth of melt penetration has correlated with rise in the estimated surface temperature induced by laser melting. Within the strongly refined structure of the laser melted alloy, the interdendritic spacing, λ varied from 0.29 μm to 0.97 μm with increase in the depth of melt penetration. The microhardness in the laser surface melted region has been shown to decrease linearly with λ−0.5.