| 摘要 |
PURPOSE:To provide excellent low-temp. toughness and high tension by subjecting a steel plate contg. a specific amt. of C, Mn, S, P, Si, Ti, Nb, V, N and solAl to electric welding, limiting the heating condition in the electric weld zone the succeeding cooling condition and setting the succeeding heating and cooling conditions. CONSTITUTION:A steel plate is composed, by weight %, of 0.01-0.08 C, <=1.5 Mn, <=0.5 Si, <=0.03 P, <=0.008 S, <=0.04 Ti, 0.001-0.05 Nb, 0.001-0.05 V, <=0.01 N, and the balance solAl that remains when the degree of deoxidation is adjusted, Fe and unavoidable impurities. Such steel plate is used in electric welding, and the electric weld zone is heated for >=5sec at 880-1,150 deg.C and is quickly cooled at a cooling rate of 30-150 deg.C/sec from 750-950 deg.C. The weld zone is further heated for 5-30sec to 790-1,050 deg.C and is quickly cooled at a cooling rate of 30-150 deg.C/sec from 750-950 deg.C to form ultrafine acicular ferrite texture. |
