Low alloy steel nitrided in fused salt bath - at the A1 transformation temp. with additives for hardening, strengthening and improving machinability

摘要

To steel of compsn.: 0.03-0.50% C, 0.10-1.50% Si, 0.10-1.50% Mn, 0.70-3.0% Cr, 0.02-0.50% Al and usual impurities, is added (a) is not 0.2% of =1 element to act as hardener selected from Ti, V, Nb, Ta and Zr; and/or (b) is not 1.5% of =1 element to strengthen the matrix, selected from Ni, Cu, Mo, W and Co; (c) is not 0.15% S, 0.30% Pb, 0.30% Te (Pb+Te is not 0.40%), and/or 0.30% Se, these elements improving the machineability. The steel is nitrided for 5 hr. max. in a fused salt bath and/or nitriding atmos. at 550-650 degrees C and pref. deoxidised with Al, Fe silicate or Ca silicate and deformed prior to nitriding.