Niobium-containing axle for urban rails and subways and heat treatment technology thereof

Abstract

The invention provides a niobium-containing axle for urban rails and subways and a heat treatment technology thereof. The axle is prepared from the components of: 0.34 0.39% of C, 0.20 0.35% of Si, 1.40 1.60% of Mn, 0.25 0.45% of Cr, 0.10 0.20% of Ni, 0.10 0.20% of Mo, 0.015 0.050% of Nb, 0.0010 0.0050% of Ca, 0.0015 0.0030% of B, less than or equal to 0.010% of P, less than or equal to 0.008% ofS, less than or equal to 0.0010% of T[O], 0.015 0.035% of Als, and the balance of Fe and other unavoidable impurities. According to niobium-containing axle for urban rails and subways and the heat treatment technology thereof, the heat treatment technology of "normalizing + tempering (quenching + tempering at high temperature)" is adopted, and the axle has the advantages of low cost, high strengthand excellent fatigue resistance.

Description

technical field [0001] The invention belongs to the field of alloy steel, and in particular relates to a niobium-containing urban rail subway axle and a heat treatment process thereof. Background technique [0002] The axle is one of the most important moving and load-bearing parts in various vehicles related to safety. Because the vehicle bearing is subjected to dynamic loads, the force state is relatively complicated, such as bending load, torsional load, bending-torsion composite load, and is subject to certain impacts, especially for urban rail subway axles, and its force state is more complicated. Therefore, urban rail subway axles may break due to fatigue, bending, torsion or tensile stress during service, among which fatigue fracture is a common fracture form of high-speed axles. In order to ensure the safe operation of the vehicle, the axle of the urban rail subway must have sufficient reliability and fatigue safety factor. Urban rail subway axle material is one of...

AI Technical Summary

Problems solved by technology

[0003] With the rapid development of urban rail transit, the demand for axles has increased sharply. At present, domestic and foreign markets, especially in Europe and Asia, still mainly use EA1N and EA4T material axles in the standard EN13261. EA1N is a positive train axle and is mainly used in low-speed cities. Rail and subway models, the fatigue strength is low, which can no longer meet the high-speed development needs of urban rail subways. EA4T is an alloy steel axle, and the heat treatment process is quenched and tempered heat treatment, but the internal structure of large-scale urban rail subway axles (the presence of ferrite that is not allowed to exist) and performance (low strength, toughness and fatigue performance near the center), it is often difficult to meet the requirements of the standard

At the same time, the high content of Cr, Mo, and Ni leads to high production cost of the axle, which is limited in practical application. Therefore, it is urgent to develop an economical new material urban rail with high strength, high toughness and long fatigue life. subway axle

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