Improving the Surface Hardness and Wear Resistance of S45C Carbon Steel Via Various Heat Treatments and pH Values of Electroless Ni-P Deposition

This research focused on studying the effects of a surface microstructure on S45C carbon steel using different pH values of electroless Ni-P plating. Meanwhile, the authors make an effort to improve the surface hardness and wear resistance of S45C steels through various heat treatments. The experimental results show that the specimens using acid and alkaline baths of pH5 and pH8 resulted in maximum hardness; the hardness values were the HV0.05 701 and HV0.05 803, respectively. Moreover, pH5 and pH8 of Ni-P deposition after 350 and 300 °C and soaked for 1 h heat treatment, in which the highest hardness appeared, were HV0.05 1027 and HV0.05 1066, respectively. The specimens underwent the main precipitate phase of Ni3P after heat treatment. Due to precipitation, strengthening of the Ni3P phase increased the surface hardness of specimens after heat treatment; thus, the wear depth was decreased and wear resistance was enhanced. The optimal wear depth (2.738 μm) and (2.923 μm) appeared in Ni-P deposition by pH5 and pH8 after 350 and 300 °C and soaked for 1 h heat treatment, respectively.