A METHOD FOR MANUFACTURING A SOFT COLD ROLLING STEEL SHEET HAVING HIGH FORMABILITY AND ANNEALED HARDENABILITY

摘要

PURPOSE: Soft small part hardenability cold rolling steel plate with peel strength 30kgf/mm¬2 below and small part hardening quantity 3kgf/mm¬2 over using in core processed region like quarter panel among internal and external board plank of vehicle by cold winding with using ultra low carbon AL solid steel added ultra low volume Ti as carbohydrate formative element. CONSTITUTION: Soft small part hardenability cold rolling steel plate with plasticity by improving plasticity with solid-solution decreasing effect causing Tic precipitation by forming stable Tic precipitation partially and small part hardenability by securing optimum solid-solution carbon with remelting of Tic precipitation material in continuous annealing operation is manufactured by finishing hot rolling in the temperature range of 900-950C after homogenizing heat treatment ultra low nitrogen and ultra low carbon AL solid steel added Ti over 1200C, cold rolling after forming low volume Tic precipitation by cold winding in the temperature range of 500-600C, continuous annealing in the temperature range of 800-860C, temper rolling of 1.0-2.0%.