Axletree steel and heat treatment method thereof

Abstract

The invention provides axletree steel and a heat treatment method thereof. The axletree steel comprises the following constituents: 0.42 to 0.45% of C; 0.23 to 0.30% of Si; 0.53 to 0.63% of Cr; 0.73 to 0.83% of Mn; 0.08 to 0.13% of Mo; 0.18 to 0.25% of Ni; 0.05 to 0.15% of Cu; 0.025 to 0.050% of Al; 0.09 to 0.11% of V; 0.015 or less ppm of P; 0.010 or less ppm of S; and Fe and other inevitable elements in balancing amount. The axletree steel has high rotation fatigue point index, yield strength and tensile strength; and an axletree prepared with the axletree steel is not liable to crack in a fatigue use process so as to achieve a longer service life, and can realize the advantage of safe driving under the conditions of acceleration and heavy duty.

Description

technical field [0001] The invention relates to metallurgical technology, in particular to a steel for axles and a heat treatment method thereof. Background technique [0002] The axle is the key part of the vehicle to bear the dynamic load. It mainly bears the bending load, torsional load or combined bending and torsion load, and is subject to certain impact. Therefore, the steel used for the axle must ensure that the axle does not break due to fatigue, bending, torsion or tensile stress during work, and the focus is to prevent fatigue cracks on the axle. [0003] At present, the axles of railway wagons in various countries are basically made of medium carbon steel. For example, the carbon content of LZ50 steel currently used in my country is 0.47% to 0.57%. The composition of the LZ50 steel is shown in Table 1, the balance is iron, and the TB / T 2945-1999 standard is implemented. [0004] Table 1 Composition of LZ50 steel (the balance is iron) [0005] [0006] The ab...

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Problems solved by technology

[0009] After the above-mentioned LZ50 steel axle has been normalized twice and tempered once, the problem of grain size mixed crystals is prone to occur. Under a high-power microscope with a magnification of 100 times, the image is as follows figure 2 As shown, the grain size of LZ50 steel is 4-6

In addition, during the forging process of axle steel, the final forging temperature of 870-900°C is often experienced, but the existing LZ50 steel is prone to grain size fluctuations at this temperature, such as image 3 As shown (under a high-power microscope with a magnification of 100 times), under the condition of the final forging temperature of LZ50 steel at 900°C, the material has obvious mixed crystal phenomenon, and the grain size is 3-6, which seriously affects the mechanical properties of the axle.

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