Spring steel and manufacturing and thermal treatment method thereof

Abstract

The invention discloses a spring steel, which comprises the following components in percentage by mass: 0.3 to 0.5 percent of C, 1.0 to 2.5 percent of Si, 0.3 to 1.5 percent of Mn, 0.1 to 1.0 percent of Cr, 0.01 to 0.30 percent of Ni, less than or equal to 0.15 percent of Cu, less than or equal to 0.010 percent of P, less than or equal to 0.010 percent of S, and the balance of Fe and inevitable impurities, wherein the spring steel can be manufactured into high-speed railway rail buckles by a processing method of cold forming. The invention also discloses a manufacturing and thermal treatment method of the spring steel. By the method, the yield strength (Rm) of the spring steel is more than or equal to 1,000MPa, the tensile strength (Rp0.2) is more than or equal to 1,200MPa, the elongationrate (A) is more than or equal to 6 percent, the section shrinkage rate (Z) is more than or equal to 30 percent, and the buckle requirements of high-speed railway rails are met.

Description

Technical field [0001] The invention belongs to the technical field of ferrous metal material manufacturing and processing, and specifically relates to a spring steel in the metallurgical industry and a manufacturing method thereof. The spring steel can be used to manufacture high-speed railway track fasteners. Background technique [0002] Before the speed increase of domestic high-speed railways, the train speed was 120-180 km / h. The spring steel of railway track fasteners was mainly designed with high carbon chemical composition, such as C 0.56~0.64%, Si 1.60~2.00%, Mn 0.70~ 1.00%, Cr≤0.35%, Ni≤0.25%, P≤0.025%, S≤0.0250%. The manufacturing process is usually: primary refining→LF refining (high basicity slag, aluminum deoxidation)→VD refining→continuous casting→ Heating → rolling → inspection → qualified storage → users use hot coil spring forming → oil quenching and oil tempering for quenching and tempering. This spring steel has a certain strength (tensile strength ≥1600Mpa),...

AI Technical Summary

Problems solved by technology

[0004] (1) High carbon content (0.56-0.64% C), high steel strength (tensile strength ≥ 1600Mpa), low toughness and plasticity (section reduction rate ≥ 30%);

[0005] (2) The traditional spring steel smelting adopts aluminum deoxidation and high-basicity slag vacuum refining technology, and the brittle inclusions Al in the steel 2 o 3 It is not easy to float and remove, and the gas content is high;

[0006] (3) Due to the high carbon content, the steel is highly sensitive to decarburization during rolling and thermal processing, the decarburization layer is thick (1.5% D), and the fatigue life of the fastener is low during use;

[0007] (4) Since the carbon content of the traditional spring steel is as high as 0.54-0.64%, the steel is hard, and the user needs to heat and then heat form it during use. At the same time, due to the high carbon content, the thermal stress in the quenching and tempering process is large. Water medium can cause stress cracks in steel, oil quenching and oil tempering must be used, which increases the process and energy consumption, and the production efficiency is low

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