Nb-Ti microalloying high-temperature-resistant carburizing gear steel and manufacturing method thereof

Abstract

The invention discloses Nb-Ti microalloying high-temperature-resistant carburizing gear steel and a manufacturing method thereof, and belongs to the field of alloy steel. According to the method, a composite microalloying mode is adopted, Ti microalloy elements are added, the nitrogen content is reduced, precipitation of titanium nitride is reduced, the influence of TiN on the fatigue performance of the steel is reduced, a second phase such as Ti (C, N) and Nb (C, N) is separated out from the steel, austenite grains are prevented from growing by pinning grain boundaries of the second phase, the high-temperature carburizing effect of the gear steel is achieved, the gear carburizing heat treatment process time is shortened, energy consumption is reduced, the grain size detected according to GB / T 6394 is larger than or equal to 8.0 level after carburizing is conducted on the material at the temperature of 1040 DEG C , and the grain mixing phenomenon is avoided.

Description

technical field [0001] The invention belongs to the field of alloy steel, and more specifically relates to a Nb-Ti microalloyed high temperature resistant carburizing gear steel and its manufacturing method, which is suitable for manufacturing heavy-duty locomotive gears, and can also be used for wind power, high-speed rail, and heavy-duty vehicles Carburizing gear manufacturing in other fields. Background technique [0002] Gear steel is a key material with large consumption and high requirements in the field of special steel, and is widely used in machinery, transportation, energy and other fields. The performance requirements of gear steel not only affect the technical and economic indicators such as the service life of the equipment, but also affect the requirements of safety in use. The working environment of the gear is complex and harsh, and the main failure forms are the wear of the meshing surface, pitting and spalling caused by contact fatigue, and cracks or fract...

AI Technical Summary

Problems solved by technology

However, increasing the carburizing temperature will inevitably bring carburizing defects such as mixed crystals, resulting in unqualified parts

[0005] Chinese patent, publication number CN 106967925A, discloses a high-temperature carburized gear steel with fine grain and narrow hardenability bandwidth. By adding Al and N to the gear steel, the steel can be carburized at high temperature. Medium AlN hinders the growth of austenite grains. The defect is that the addition of Al to the steel easily produces a large number of brittle inclusions, which is not conducive to improving the fatigue strength of the gear. At the same time, the high Al content makes the castability of molten steel worse

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