Improvements in and relating to the manufacture of deep drawing sheet, iron or steel

摘要

In a process of producing a deep drawing iron or mild steel sheet or strip in which the stock is hot rolled, then cold rolled and subsequently stabilised by heat treatment, the hot rolled stock at a temperature not lower than 1525 DEG F. is rapidly cooled to between 1100 DEG F. and 1375 DEG F. and then slowly cooled to the cold rolling temperature. In an example, a steel containing up to .08 per cent carbon, .15 to .40 per cent manganese with low copper and sulphur content is deoxidised with aluminium which is added in an amount such as to leave a residue of .02 to .08 per cent. Ingots of this steel are hot rolled to about .10 inches, finishing the rolling operation in the range of 1525 DEG F. to 1650 DEG F. or higher. The material is then cooled in air, or more rapidly to between 1100 DEG F. and 1375 DEG F. after which the cooling to atmospheric temperature is retarded by coiling or stacking according to whether the material is in strip or sheet form. The material is then reduced from 30-70 per cent by cold rolling and is annealed at 1250 DEG F. to 1400 DEG F. for four or more hours and then cooled to room temperature at a slow rate preferably about 25 DEG per hour. Sheets made in this manner have a flattened or spheroidal grain characteristic, are non-aging and have good deep drawing characteristics. U.S.A. Specification 2,069,758 is referred to.