Method for producing ultra-low carbon high-strength cold rolling sheet

Abstract

The invention provides a method for producing an ultra-low carbon high-strength cold rolling sheet. Carbon content in traditional IF steel is properly increased. Alloying elements of Mn, P, Si, and the like which have a reinforcement effect on steel are added, and elements of Nb and Ti which can form second phase precipitation particles are also added to ensure that the second phase in the steel can be precipitated in a reasonable particle size. Hot rolling and cold rolling technological parameters are controlled. A hot rolling low-temperature coiling technology is used to avoid the formation of FePTid, and further to prevent the destruction effect of the FePTid on steel sheet stamping performance and a steel sheet elongation percentage. By adjusting the cold rolling technology, the steel sheet can have a relatively high [111] texture, and therefore can acquire high tensile strength, a high elongation percentage, and a high r value, to guarantee steel mouldability and shock resistance. A test detection on the steel sheet after the cold rolling shows that the average yield strength of the steel sheet reaches 287 MPa, the tensile strength is 460 MPa, the elongation percentage is 36%, the deep stamping performance index r is equal to 1.74, n is equal to 0.202, and other performance indexes also meet standard requirements.

Description

technical field

[0001] The invention belongs to the field of smelting and rolling technology, and in particular relates to a production method of an ultra-low-carbon high-strength cold-rolled sheet with excellent formability. Background technique

[0002] Modern automobile sheets have extremely high requirements on formability and surface quality, so that the third generation of automobile stamped steel sheets - ultra-low carbon series products have become the center of international key production and research. The so-called ultra-low carbon steel refers to steel types with carbon weight percentage ≤ 0.004%. The characteristics of traditional ultra-low carbon steel not only require extremely low carbon content in steel and good deep drawing performance; but also require strong deformation ability to prevent cracking during stamping; at the same time, it also requires good plastic strain ratio (r value ) and tensile strain hardening exponent (n value) to ensure that the ste...