A kind of nb-ti microalloying high temperature resistant carburizing gear steel and its manufacturing method

Abstract

The invention discloses a Nb-Ti microalloyed high temperature resistant carburizing gear steel and a manufacturing method thereof, belonging to the field of alloy steel. It includes that the present invention adopts a composite microalloying method, adds Ti microalloy elements and reduces nitrogen content, reduces the precipitation of titanium nitride and reduces the influence of TiN on its fatigue performance. The second phases such as Ti (C, N) and Nb (C, N) are precipitated in the steel, and the pinning grain boundaries are used to prevent the growth of austenite grains. Realize the effect of high-temperature carburizing of gear steel, shorten the heat treatment process time of gear carburizing, and reduce energy consumption. After carburizing at 1040°C, the grain size of the material of the present invention is ≥8.0 according to GB / T 6394, and no mixed crystal phenomenon occurs.

Description

technical field [0001] The invention belongs to the field of alloy steel, and more particularly relates to a Nb-Ti microalloyed high temperature resistant carburizing gear steel and a manufacturing method thereof, which are suitable for manufacturing heavy-duty locomotive gears, and can also be used for wind power, high-speed rail, and heavy-duty automobiles. and other fields of carburizing gear manufacturing. Background technique [0002] Gear steel is a key material with a large amount 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 life of the equipment, but also affect the requirements of safety in use. The working environment of gears is complex and harsh, and the main failure modes are wear of meshing surfaces, pitting spalling caused by contact fatigue, cracks or fractures caused by...

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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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