Effect of Grinding, Polishing and HCl on Surface Roughness of Low Carbon Steel

The low carbon steel is used in many structural applications in industrial plants and they are susceptible to environmental changes that may affect their surface properties and mechanical performance. The aim of this paper is to investigate the effect of mass loss by mechanical material removal and by chemical etching with hydrochloric acid (HCl) on the surface roughness of low carbon steel. The low carbon steel samples are cut from 25 mm diameter cylindrical bar in 15 mm thickness approximately and then mounted on a polymeric resin to hold them firmly. Each sample is then subjected to four different surface mechanical material removal stages; rough grinding, fine grinding, rough polishing and fine polishing, respectively. Surface roughness measurements were done after each stages using Alicona InfiniteFocus roughness tester. Considering the possibility of anisotropy and inhomogeneity of the sample surface, the surface roughness analysis are done in four different angles with 45⁰ increment in each sample. Every stage of the material removal from the surface reduced the surface roughness from 115.8 nm to 54.8 nm. Based on the final polished samples surface roughness results, selected sample is tested to determine the effect of mass loss by etching on the surface roughness. Sample is exposed to 6 M HCl solution for different time durations and mass loss measurements done after each time period. The total material loss after 90 minutes is reached to 0.0541 g. On the other hand, the surface roughness of the material is increased exponentially by etching time from 160.3 nm to 650.6 nm. Also, after 90 minutes chemical etching the mass loss rate become stable. As conclusion, the surface roughness measurement and analysis method used for Alicona InfiniteFocus surface roughness tester can be also used in any application involve material removal process such as wearing, corrosion and tribology.