PRODUCTION OF HOT DIP GALVANNEALED AND HOT ROLLED STEEL SHEET,申请号JP19980280312-传众专利搜索

PRODUCTION OF HOT DIP GALVANNEALED AND HOT ROLLED STEEL SHEET

申请公布号：JP2000109964(A)

申请号：JP19980280312

申请日期：1998.10.01

申请公布日期：2000.04.18

申请人：

SUMITOMO METAL IND LTD

发明人：NOMURA SHIGEKI;SATO NAOHIRO

分类号：C23C2/02;C21D9/46;C22C38/00;C22C38/06;C22C38/38;C23C2/06;C23C2/28;(IPC1-7):C23C2/06

主分类号：C23C2/02

摘要：PROBLEM TO BE SOLVED: To provide a method for stably and inexpensively producing a high tensile strength hot dip galvannealed and hot rolled steel sheet of a low yield ratio having a good hot dip galvannealing layer. SOLUTION: A slab having a compsn. contg., by weight, 0.03 to 0.11% C, <=0.3% Si, 1.8 to 2.7% Mn, <=0.05% P, <=0.010% S, 0.005 to 0.08% Al and <=.0080% N, or further contg. one or more kinds among Cr, Ca and Ti and the balance Fe with inevitable impurities is heated at 1100 to 1280 deg.C, is subjected to finish rolling at the temp. equal to or above the Ar3 point, is thereafter cooled to 400 to 650 deg.C at a cooling rate of >=5 deg.C/s, is coiled and is moreover subjected to skinpass treatment of 0.3 to 2.0% elongation percentage and subsequent pickling. Then, in continuous hot dip galvanizing equipment, it is heated at 750 to 930 deg.C for >=5 sec, is thereafter cooled to 450 to 550 deg.C at a cooling rate of >=2 deg.C/s, is applied with hot dip galvanizing, is moreover subjected to alloying treatment in the temp. range of 480 to 650 deg.C and is cooled to <=200 deg.C at a cooling rate of >=2 deg.C/s.