A kind of gear steel resistant to high temperature carburizing grain growth and control method

Abstract

A gear steel resistant to high temperature carburizing grain growth and a control method thereof, belonging to the technical field of gear steel. The continuous casting slab or ingot of gear steel produced by the smelting process of converter or electric furnace + refining outside the furnace + continuous casting or mold casting has the following composition: the weight percentage of chemical composition is: C: 0.15-0.22%, Si: ≤0.40%, Mn: 0.51-0.90%, Cr: 1.5-1.8%, Ni: 1.4-1.7%, Mo: 0.25-0.35%, Nb: 0.02-0.09%, Al: 0.01-0.04%, P: ≤0.02%, S: ≤0.03%, N: 0.005~0.02%, the rest is Fe and unavoidable impurities. And the ratio of Al:N should be 1.95-4.50, and Nb+Al≥0.045%. The advantage is that a carburized gear blank with fine grain size and uniformity can be obtained.

Description

technical field [0001] The invention belongs to the technical field of gear steel, and in particular provides a gear steel resistant to high-temperature carburizing grain growth and a control method; it is suitable for the production of driving and driven gear blanks for gear boxes of heavy-duty vehicles and rail transit locomotives And carburizing heat treatment, as well as the production and heat treatment of wind power gear blanks, it can also be used for the production and heat treatment of other large equipment gear parts blanks. Background technique [0002] At present, the carburizing temperature of commonly used gear steel in China generally does not exceed 930°C. When carburizing at a temperature below 930°C, due to thermodynamic conditions, the grain growth is slow. At the same time, the precipitated phase of AlN in the gear steel can exist stably and will not dissolve. , can play a pinning effect on the grain boundary, prevent the migration of the grain boundary, ...

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Problems solved by technology

[0004] Chinese patent CN101096742A discloses a high-strength automotive gear steel. Alloying elements such as Nb, V, and Al are compounded in the steel, which can have the effect of refining grains, but the compound addition of Nb and V improves the production of materials. Cost, especially V, the current raw material cost of V is several times higher than in the past

[0008] At present, the microalloying elements used in my country's gear steels to inhibit grain growth during carburizing are mainly Al, Nb, V, Ti, etc. Al is the most commonly used element for grain refinement, and it prevents grain growth through the precipitation of AlN. The role of grain growth, but it is easy to fail when it is carburized at a high temperature above 960 ° C. Nb can form Nb (C, N) precipitates in the gear steel, which can exist more stably when carburized at high temperature. V is in the gear steel In metals, Nb is usually compounded and microalloyed to refine the grains, but the high cost of V limits its large-scale application, and Ti, as a low-cost element, can solve the problem of material cost, but gear steel A small amount of Ti content in the steel may lead to the formation of more harmful TiN inclusions in the steel, which seriously affects the fatigue performance of the gear

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