Nanostructure carbide-free bainite medium-carbon alloy steel and preparation method

Abstract

Nanostructure carbide-free bainite medium-carbon alloy steel comprises the following chemical components by weight: 0.48-0.52 parts of C, 1.2-1.3 parts of Si, 1.7-1.9 parts of Mn, 1.0-1.4 parts of Al, 1.6-1.8 parts of Cr, 0.5-0.6 parts of Ni, 1.9-2.3 parts of W, less than 0.02 parts of P, less than 0.02 parts of S, and the balance of Fe; the preparation method comprises the following steps: melting the medium-carbon alloy steel with the above components by a vacuum induction furnace, casting to form a steel ingot, slowly cooling to room temperature; heating, performing heat preservation, forging after the steel ingot is taken out of the furnace, slowly cooling to room temperature; heating and austenitizing the product, rapidly cooling to a supercooled austenite temperature range, performing compression deformation with a strain rate of 0.01 s-1 and a press quantity of 50%, rapidly cooling to a temperature slightly higher than a martensite transformation starting temperature, performing isothermal transformation, and cooling to room temperature. The carbon content of the alloy steel of the invention is greatly reduced when compared with that of high-carbon steel, which not only facilitates the improvement of solderability and impact toughness, but also shortens the treatment period, and reduces material cost.

Description

technical field [0001] The invention relates to a preparation method of alloy steel. Background technique [0002] Steel, which is widely used as a structural material, increases in strength as the carbon content increases, but decreases in toughness and plasticity. How to realize the synchronous improvement of the strength and toughness or plasticity of steel has become an important issue to improve its performance and tap its potential. Traditional low-alloy high-carbon steel is generally used to manufacture cutting tools, measuring tools and cold-working molds. The enhanced heat treatment process is mainly quenching + low-temperature tempering. After heat treatment, a tempered martensite structure is obtained, which has high strength and high hardness, but its Low toughness and plasticity. If the tempering temperature is increased, although the toughness and plasticity can be improved, the strength and hardness will be greatly reduced. [0003] Bhadeshia et al. (U.S. P...

AI Technical Summary

Problems solved by technology

Chinese invention patent CN101693981B discloses a method for preparing high-strength, high-toughness nanostructure low-alloy high-carbon steel, that is, adding Mn, Cr, Si, Al, W to high-carbon steel for alloying, casting ingots and hot rolling into slabs to eliminate Casting defects, hot-rolled slabs are directly transformed into isothermal bainite in a salt bath to obtain a nanostructured carbide-free bainite structure composed of nano-scale thick lath-shaped bainitic ferrite and retained austenite, In order to ensure that high strength and high plasticity and toughness can be obtained at the same time, but its high carbon content will inevitably make the weldability and impact toughness of the steel poor, which limits its application range as structural steel

Images