ELECTRIC RESISTANCE WELDED STEEL TUBE FOR MACHINE STRUCTURAL USE HAVING EXCELLENT MACHINABILITY

摘要

PURPOSE:To obtain the electric resistance welded steel tube for machine structural use having excellent machinability by specifying a compsn. constituted of C, Si, Mn, P, S, Al, N, O, Ca and Fe, making a tube by electric resistance welding and thereafter executing a specified heat treatment. CONSTITUTION:The electric resistance welded steel tube for machine structural use having excellent machinability is the one contg., by weight, 0.02 to 0.60% C, =0.4% Si, 0.20 to 2.0% Mn, =0.030% P, 0.005 to 0.025% S, 0.001 to 0.040% sol.Al, =0.0060% N, =0.0060% O, 0.002 to 0.020% Ca as well as satisfying =0.05 Ca/(1.25O+0.625S), if required, furthermore mixed with 0.10 to 1.50% Cr and 0.10 to 0.60% Mo and the balance Fe with inevitable impurities, and can be obtd. by making a tube by electric resistance welding and thereafter executing heat treatment at =500 deg.C. In the steel tube the amounts of S, Ca and O are specified to prevent the deterioration of its weldability and to improve its yield.