PURPOSE: To produce a steel plate of superior tensile strength, workability and weldability in the production of a high-strength hot-rolled steel plate for automobiles by combining component control for C, Si, Mn, etc. and specific hot rolling conditions.
CONSTITUTION: A steel slab contg. 0.05W0.15% C, <1.5% Si, 0.7W1.5% Mn, <0.01% P, <0.005% S, 0.01W0.10% Al is heated to ≤1,200°C and is hot-rolled, wherein the end temp. of finish rolling is set at Ar3 transformation pointW930°C. The hot-rolled steel plate is coiled at 350W600°C, whereby the steel plate having the 2-phase structure of ferrite and dense pearlite is produced. Or further 1 or ≥2 kinds among 0.0005W0.0050% Ca, 0.005W0.015% REM and 0.0005W0.010% Mg are contained therein and sulfide type inclusions are reduced or spheroidized. The hot rolled steel plate of 1.6W4.0mm thickness provided with 50kgf/mm2 tensile strength and superior workability and weldability is obtained.
KOYAMA KAZUO
GOTOU KAZUYOSHI
| JPS54131524A | 1979-10-12 | |||
| JPS5723025A | 1982-02-06 |