High-strength high-toughness high-hardenability high-speed axle steel and heat treatment method thereof

Abstract

The invention relates to high-strength high-toughness high-hardenability high-speed axle steel. The yield strength Rp0.2 of the axle steel is larger than or equal to 630 MPa, the strength of extensionRm is larger than or equal to 800 MPa, the ductility A is larger than or equal to 20%, the 5 mm notch indoor temperature longitudinal impact absorbing energy KU2 is larger than or equal to 80 J, andthe ductile-brittle transition temperature is lower than -40 DEG C; and a chemical component of the steel comprises B, and the weight percentage of the B is 0.0008%-0.0025%. Meanwhile, a preparing method of the steel is further provided. By means of the high-strength high-toughness high-hardenability high-speed axle steel and the preparing method have the beneficial effects that full play can be given to the effects of all elements in the axle steel sufficiently, and microscopic structures with wee crystalline grains and with martensite as a main are obtained. Through two times of quenching and high temperature tempering heat treatment are adopted, and therefore even fine grain austenite grains and Nb microalloy second-phase strengthened martensitic structures can be obtained, excellent matching of high strength, high toughness and high hardenability is achieved, and finally the high-speed axle steel has the good anti-shock, anti-fatigue service performance and the like, excellent strength and toughness matching and good hardenability.

Description

technical field [0001] The invention relates to the technical field of steel for railway axles, in particular to a high-speed axle steel with fine grain, high strength and toughness and high hardenability and a heat treatment method thereof. Background technique [0002] Axle is one of the most demanding components of rail transit trains, bearing almost all the weight and load of the train. With the high-speed railway in my country put into operation, the train speed is further increased, which makes the dynamic load of the axle continue to increase, which brings great challenges to the safety and reliability of the axle, and puts forward higher requirements for the performance of the axle material. Due to the different national conditions and technical ideas of various countries, the axle materials of high-speed railways in developed railway countries in the world are mainly divided into two categories: high-quality medium carbon steel and high-strength alloy steel. For ex...

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Problems solved by technology

Chinese patent 201410532111.7 provides an axle steel. On the basis of the chemical composition of EA4T steel, the hardenability of the steel is improved by adding Nb0.015-0.060wt.%, B0.0008-0.0050wt.%. Take effective measures to fix the N in the steel, and some B will combine with the excess N to form BN, so that the effect of improving hardenability cannot reach the expected effect. Uneven, reducing the performance of the axle

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