INCREASING METHOD FOR HARDNESS OF NITRIDING LOW CARBON LOW ALLOY STEEL BY REHEATING

摘要

PURPOSE:To accelerate the formation of Si3N4 which had been insufficient in a nitriding state and further increase the surface hardness of this alloy steel by reheating the nitriding low carbon low alloy steel having been nitrided within the specified temperature range. CONSTITUTION:The nitriding low carbon low alloy steel composed of C; 0.15- 0.30%, Si; 2.0% or less, Mn; 1.0% or less and the rest Fe and unavoidable impurities is subjdcted to nitriding treatment at temperatures of 500-600 deg.C in, e.g., a NH3 gas atmosphere. Thence, the alloy steel having been subjected to the nitriding treatment is reheated at temperatures of 200-600 deg.C, whereby its surface hardness is further increased.