Ultra-high strength steel with excellent corrosion resistance and fatigue resistance and its making process

Abstract

The present invention discloses one kind of ultra-high strength steel with excellent corrosion resistance and fatigue resistance and its making process. The ultra-high strength steel consists of C 0.05-0.12 wt%, Si 0.05-0.50 wt%, Mn 1.10-1.70 wt%, P not more than 0.015 wt%, S not more than 0.010 wt%, Nb 0.025-0.070 wt%, V 0.005-0.080 wt%, Mo 0.20-0.50 wt%, Ni 0.30-0.80 wt%, Ti 0.005-0.025 wt%, Cu 0.25-0.80 wt%, B 0.0005-0.0020 wt%, and Cr 0.10-0.70 wt%, except Fe and inevitable impurities. It has carbon equivalent not lower than 0.65 % and heat sensitive coefficient not lower than 0.30 %. Its making process includes the steps of smelting, desulfurizing molten iron, combined blowing in converter, vacuum treatment, casting into plate blank, etc. It has yield strength not lower than 880 MPa, tensile strength not lower than 980 MPa and V-shaped notch Charpy absorbed-in-fracture energy at -20 deg.c not lower than 100J.

Description

technical field [0001] The invention relates to the field of manufacturing micro-alloyed steel, in particular to an ultra-high-strength steel with excellent corrosion resistance and fatigue resistance, and a method for manufacturing a hot-rolled plate and a medium-thick plate of the ultra-high-strength steel. The ultra-high strength steel plate can be used to manufacture high-quality engineering machinery, especially hydraulic supports and lifting equipment for coal mines. Background technique [0002] Construction machinery refers to equipment used in mining and various engineering constructions, such as dump trucks, excavators, bulldozers, trucks, various lifting equipment, and coal mine hydraulic supports, etc. The materials for welded structural parts required for the manufacture of these construction machinery are usually called steel for construction machinery. As the world's energy becomes increasingly tight, weight reduction, energy saving, ...

AI Technical Summary

Problems solved by technology

[0003] Before the application of the present invention, the Chinese Invention Patent Application Publication No. 200310105914.6 introduced a microalloyed steel and its application. The disadvantage is that the tensile strength of the steel plate prepared by this method is only about 590MPa , the strength is low, and there are no copper, chromium, molybdenum and other alloys in the microalloyed steel that can improve the corrosion resistance and fatigue resistance of the steel, so its corrosion resistance and fatigue resistance are not high, and it is used to prepare lifting equipment It is easy to break and damage when using hydraulic supports in coal mines, and the safety performance is poor

The Chinese Invention Patent Application Publication No. 98807716.7 introduces a method for manufacturing weldable ultra-high-strength steel with excellent toughness. Steel for pipelines at around 900MPa has a narrow thickness and insufficient strength. In addition, its manufacturing process adopts direct quenching after rolling without tempering to eliminate residual stress. The prepared steel plate is easily damaged during transportation or storage. Warping deformation occurs, which is difficult to eliminate for ultra-high-strength steel, so it cannot meet the flatness requirements required for the manufacture of lifting equipment and hydraulic supports for coal mines, and cannot even be processed and used

It can be seen that the steel plate manufactured by using the above-mentioned microalloyed steel has low strength, poor corrosion resistance and fatigue resistance, and cannot meet the ultra-high strength required for the manufacture of lifting equipment and hydraulic supports for coal mines. , material requirements for excellent corrosion resistance and fatigue resistance; and the steel plate made of weldable ultra-high-strength steel as mentioned above has a narrow thickness and insufficient strength, and may be deformed during transportation or storage. It cannot meet the requirements for the manufacture of lifting equipment and hydraulic supports for coal mines