PRODUCTION OF HIGH STRENGTH AND HIGH TOUGHNESS FERRITE + PEARLITE TYPE NON-TEMPERED FORGED ARTICLE

摘要

PROBLEM TO BE SOLVED: To provide a method for producing an high strength and high toughness forged article having a balance of high strength and toughness by using an inexpensive ferrite + pearlite type non-tempered steel used for wide application. ;SOLUTION: An alloy having a compsn. contg., by weight, 0.25 to 0.55% C, ≤1.6% Si and 0.08 to 0.5% V, in which manganese equivalent Mneq expressed by Mneq=Mn+Cr+Mo+Cu+V+Ni/2+10(Nb-0.02) is regulated to 0.8 to 2.0 (where ≤2.0% Mn, ≤2.0% Cr, ≤1.0% Mo, ≤4.0% Ni, ≤1.0% Cu and ≤0.1% Nb), and the balance substantially Fe is once heated at 950 to 1300°C, is thereafter cooled to lower its temp. to 800 to 1050°C, is forged at that temp. range, is subsequently cooled and is transformed into ferrite + pearlite. If required, it is incorporated with 0.02 to 0.1% N, 0.015 to 0.010% Al and 0.010 to 0.040% N, is heated to ≥1100°C at which NbC can enter into solid solution, is once cooled to lower its temp. to 800 to 1100°C, is forged, is subsequently cooled and is transformed into ferrite + pearilite.;COPYRIGHT: (C)1998,JPO