Wear and corrosion resistance of laser surface hardened structural steel

CO2 laser surface treatment in solid state has been performed on a CK60 structural steel. The laser energy density was lower than the melting threshold and only caused surface hardening. The observed heat affected zone (HAZ) ranged in depths of 50–430 μm. Microstructure of the HAZ was composed of needle, fine-grained martensite and small amount of pearlite and retained austenite. Microhardness values changed in areas of overlapping successive laser passes. Wear tests revealed the improved wear resistance of the laser treated specimens in comparison with the untreated one. Specimens laser treated using 0 and 38% overlapping ratios exhibited improved wear resistance. The corrosion resistance exhibited a tendency to decrease with increasing overlapping ratios. Among all specimens studied the one, which was laser treated with 0% overlapping ratio presented the best wear and corrosion behaviour.