Effects of hydrogen on the abrasive wear of mild steel

Surface microhardness is affected by hydrogen content at the near surface, and also affects the abrasive wear of the material. Mild steel plate composed of 0.06% carbon, 0.28% Mn, 0.003% Si, 0.013% phosphorus, 0.013% sulfur and Fe by weight was austenitized at 900 deg C --1 h--furnace cool. Ground and polished specimens were cathodically charged with H at 5 and 10 mA cm exp --2 for times between 5-20 min, then abrasive wear tested using a rotating disk wear tester with 400-grade silicon carbide paper at room temperature. Sliding velocity was a constant 0.67 m s exp --1 , and applied stresses were either 109 or 210 N m exp --2 . As depth from the surface increased, the microhardness decreased, indicating the presence of surface dislocations. Depending on the charging conditions and applied test stress, the surface wear increased or decreased due to the H absorbed. The effect of H on work-hardening, void formation, and void coalescence is discussed.