Improved 40CrNiMo steel and preparation method thereof

Abstract

The invention relates to improved 40CrNiMo steel and a preparation method thereof, and belongs to the technical field of alloy steel. The improved 40CrNiMo steel comprises the following chemical elements in percentage by weight: 0.37 to 0.45 percent of C, 1.65 to 1.85 percent of Cr, 0.45 to 0.65 percent of Ni, 0.15 to 0.25 percent of Mo, 0.90 to 1.20 percent of Mn, 0.40 to 0.55 percent of Si, 0.0025 to 0.0045 percent of B, 0.22 to 0.28 percent of N, 0.007 to 0.012 percent of Ca, 0.002 to 0.005 percent of Mg, 0.03 to 0.06 percent of Nb, 0.04 to 0.08 percent of Ti, 0.02 to 0.06 percent of RE, less than or equal to 0.015 percent of S, less than or equal to 0.025 percent of P, less than or equal to 0.0008 percent of Al and the balance of Fe. The invention has the advantages that: the improved 40CrNiMo steel has low nickel content, so that cost can be reduced; the steel has a fine structure, the number of impurities is obviously reduced, and the impurities have a small size and are uniformly distributed, so that the performance of the steel is obviously improved; and a few process steps are performed in the preparation method, so that energy is saved, and the requirement of industrial scale-up production is met.

Description

technical field [0001] The invention relates to low-alloy medium-carbon ultra-high-strength steel and a preparation method thereof, in particular to an improved 40CrNiMo steel and a preparation method thereof, belonging to the technical field of alloy steel. Background technique [0002] 40CrNiMo steel is a low-alloy medium-carbon ultra-high-strength steel. The material has good comprehensive mechanical properties after heat treatment. The addition of chromium, nickel and other alloying elements makes it better hardenable and improves the strength and toughness of ferrite; the addition of molybdenum, chromium and other carbide-forming elements, It can prevent the growth of austenite grains, improve the tempering stability of steel, and have certain impact resistance, fracture toughness and high fatigue strength in use. [0003] The main components of commonly used 40CrNiMo steel are: 0.60~0.90%Cr, 1.25~1.65%Ni, 0.15~0.25%Mo, 0.50~0.80%Mn, 0.37~0.45%C, 0.17~0.37%Si, ≤0.025%S...

AI Technical Summary

Problems solved by technology

[0010] However, there are the following deficiencies in the technical content disclosed in the above-mentioned patent documents: one is that the hardenability of steel is low, and there is no reasonable addition of such as nitrogen and boron. The second is that it loses economy due to the high nickel content; the third is that the physical properties of steel such as tensile strength, yield strength, elongation, reduction of area, impact energy and impact toughness are still not enough to achieve Satisfactory degree; the fourth is that the preparation process is complex