发明授权
US4336080A Method for manufacturing high-strength cold-rolled steel strip excellent in press-formability 失效
用于制造压制成形性优异的高强度冷轧钢带的方法

Method for manufacturing high-strength cold-rolled steel strip excellent
in press-formability
摘要:
A method for manufacturing a high-strength cold-rolled steel strip excellent in press-formability, which comprises the steps of: preparing a slab of an aluminum-killed steel consisting essentially of, in weight percentage:______________________________________ Carbon from 0.02 to 0.06%, Manganese from 0.06 to 0.25%, Phosphorus from 0.01 to 0.06%, Soluble aluminum from 0.020 to 0.060%, Nitrogen up to 0.005%, and ______________________________________ the balance iron and incidental impurities;hot-rolling said slab to prepare a hot-rolled steel strip; coiling said steel strip at a temperature within the range of from 650.degree. to 770.degree. C.; cold-rolling said hot-rolled steel strip thus coiled to prepare a cold-rolled steel strip; subjecting said cold-rolled steel strip to a continuous annealing treatment for a prescribed period of time at a temperature within the range of from 750.degree. to 880.degree. C.; cooling said cold-rolled steel strip continuously annealed at a cooling rate of at least: exp {-5.6 (Cwt. %.gamma.+Mn wt. %/6+Si wt. %/24)+7.8} .degree.C./sec from a temperature region of from Ar.sub.1 to Ar.sub.1 +60.degree. C. to convert the structure thereof into a dual-phase structure of ferrite and a low-temperature transformation phase; and then, subjecting said cold-rolled steel strip having said dual-phase structure to an over-ageing treatment for a prescribed period of time at a temperature within the range of from 260.degree. to 360.degree. C.
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