Development of High Strength Cold-rolled-phosphorus Steel Produced by Continuous Annealing

Abstract

A high strength cold-rolled phosphorus-containing steel has been developed by continuous annealing process. The study is focussed on the improvement of Lankford value and aging characteristics of phosphorus-containing steel.
The effects of coiling temperature after hot rolling and cold reduction on Lankford value have been investigated for a low C-low Mn-B-P steel. Investigations have also made clear the effects of cooling rate after continuous annealing on the precipitation rate and the size of precipitates of carbides. Experimental results show that (1) the combination of proper coiling temperature and large cold reduction results in high Lankford value over 1.5 and (2) the combination of high paint baking hardenability over 40 MPa with retarded aging property at room temperature can be obtained in the range of cooling rate from 10 to 100 deg C/s. The factors affecting such results are also discussed.