Behavior of Carbon Steel Machine Elements in Acidic Environment

The objective of this paper is to study the surface texture behavior of low and medium-carbon steels machine elements in acidic environment using Abbott Firestone curve depending upon MATLAB software. The chemical composition of low-carbon steel is 0.16C-0.27Si-1.47Mn-0.02Al while medium-carbon steel is 0.49C-0.30Si-0.91Mn-0.03Al. They were hot-rolled at 1200°C for 30 min followed by air cooling. Two different heat treatment processes were applied on the hot-rolled samples. The first treatment was quenching after martensite finish (QAMf) and the second one was quenching and partitioning (Q&P). For 0.16C, the microstructure gives bands of ferrite and pearlite after hot-rolled steel. However, 0.49C produces coarse pearlite islands surrounded by ferrite phase. While, the microstructure after QAMf and Q&P processes contain ferrite, bainite, lath martensite, and retained austenite for 0.16C steel, and polygonal ferrite, lath martensite, and retained austenite for 0.49C steel, respectively. In low-carbon steel (0.16C), after hot-rolling, steel suffers from low exploitation zone (44%) of surface texture. However, after QAMf, low-carbon steel (0.16C) gives lower surface texture (36%). In addition, hot-rolled steel (0.16C) produces 40% voids zone while after QAMf, voids zone increases to 52% of surface texture. In medium-carbon steel (0.49C), after hot-rolling, steel produces 78% exploitation zone of surface texture. Furthermore, Q&P slightly enhances surface texture (exploitation zone) to 82%. At the same time, hot-rolled and Q&P of 0.49C steels exhibit very small number of voids for surface texture (1–4%). Therefore, 0.16C steel (hot-rolled and QAMf) is highly subjected to severe failure in etchy environment. However, 0.49C steel (hot-rolled and Q&P) is highly recommended in case of moderate safety factor.