Method for improving performance of 700MPa grade V-N micro-alloying high-strength weathering steel

Abstract

The invention discloses a method for improving the performance of 700 MPa grade V-N microalloyed high strength weathering steel. The method is specific to the characteristics of the sheet billet continuous casting and tandem rolling technology and metallurgy component, and adopts an electric furnace or a revolving furnace to smelt, refine, continuously cast sheet billet which directly enters into a roller hearth to heat after a casting blank concretes, or soaking furnace, hot rolling, laminar flow cooling and wind-up process flow. The chemical composition of molten steel is :C occupies less than or equal to 0.08Wt. percent, Si occupies from 0.25 to 0.75Wt. percent, Mn occupies from 0.2 to 2.0Wt.percent, P occupies less than or equal to 0.025Wt. percent, S occupies less than or equal to 0.040Wt. percent, Cu occupies from 0.25 to 0.60Wt. percent, Cr occupies from 0.30 to 1.25 Wt.percent, Ni occupies less than or equal to 0.65Wt. percent, V occupies from 0.02 to 0.20Wt. percent and N occupies from 0.015 to 0.030 Wt. percent. The invention takes full advantages of the characteristics of the sheet billet continuous casting and tandem rolling short flow process and adopts the V-N microalloyed technique to produce 700 MPa grade high strength weathering steel under the thinning function of VN and V (C, N) nanometer scale precipitate on crystal grain in casting blank of the sheet billet continuous casting and tandem rolling flow and the theory of precipitation strength. By the optimization design of the metallurgy component of V-N microalloyed 700MPa grade high strength weathering steel, the invention increases the low temperature impact ductility of coil of strip and improves the shaping property.

Description

technical field [0001] The invention belongs to the technical field of low-alloy steel production, and particularly relates to a method for producing high-strength weather-resistant steel with yield strength ≥ 700 MPa, fine-grained structure, good toughness, welding and forming properties, etc. by adopting a thin slab continuous casting and rolling process. Background technique [0002] 700MPa high-strength weathering steel is mainly used in the manufacture of special containers, special vehicles and high-speed train carriages, and plays an important role in reducing weight, increasing speed, increasing freight volume, prolonging the service life of equipment and reducing logistics costs. At present, many industrially developed countries in Japan and Europe such as Germany and Sweden have developed ultra-high-strength weathering steel with a yield strength of more than 700MPa through the traditional process of Nb, V, Ti, and Mo composite microalloying technology, and are wide...

AI Technical Summary

Problems solved by technology

However, in the actual application process, it was found that some coils of high-strength weather-resistant steel plates with a yield strength of 700 MPa produced by V-N micro-alloying technology have low low-temperature impact toughness, and cracks are prone to appear during the stamping process, which affects product quality.