Production of cold rolling high-strength ultra-deep-drawing steel plate by bell-type furnace and method for manufacturing same

Abstract

The process of producing cold rolled high strength extra-deep drawing steel sheet in a bell type furnace includes the following steps: 1. smelting and casting steel billet with chemical composition comprising C not more than 0.006 wt%, Si not more than 0.30 wt%, Mn 0.15-1.40 wt%, P not more than 0.08 wt%, S not more than 0.02 wt%, N 0.001-0.005 wt%, Al 0.03-0.06 wt%, B 0.0003-0.002 wt%, Ti 0.005-0.015 wt%, Nb 0-0.03 wt%, and Fe and inevitable impurity for the rest; 2. heating to 1100-1250 and rolling; 3. cold rolling in the reduction rate over 73 %; 4. annealing inside a hydrogen or nitrogen-hydrogen bell type furnace at 690-730 deg.c and 5. leveling after annealing. The steel sheet has strength up to 390 MPa, high elongation and r value, high ability of resisting rework brittleness, and ductile-brittle transition temperature lower than -40 deg.c.

Description

technical field [0001] The invention relates to a cold-rolled high-strength ultra-deep-drawn steel plate and a manufacturing method thereof, in particular to a cold-rolled high-strength ultra-deep-drawn steel plate produced by a bell annealing furnace and a manufacturing method thereof. Background technique [0002] The use of high-strength steel plates is a major development trend of modern automotive steel. Generally speaking, as the strength of the steel plate increases, the stamping performance decreases. It is the common wish of the automobile and steel industries to develop a steel plate with both high strength and good stamping performance. On the basis of ultra-low carbon interstitial atom-free steel (IF), by adding solid solution strengthening elements such as P, Mn and Si, a steel plate with both high strength and good stamping performance can be obtained. [0003] High-strength IF cold-rolled steel plate is a high-strength steel plate widely used in automobile bo...

AI Technical Summary

Problems solved by technology

[0007] 1. The investment of the continuous annealing production line is relatively high;

[0008] 2. A high annealing temperature is required, about 840°C, which consumes more energy, and the high annealing furnace temperature also reduces the life of the furnace;

[0009] 3. The automation of the production line and the requirements for operators are high, and the belt is easy to break if the control is not good;

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