A high temperature vacuum carburized gear steel

Abstract

The invention discloses high-temperature vacuum carburized gear steel. The high-temperature vacuum carburized gear steel comprises: by weight, 0.10 to 0.30% of C, 0.15 to 0.25% of Si, 0.60 to 0.90% of Mn, less than or equal to 0.025% of P, 0.010 to 0.020% of S, 0.85 to 1.25% of Cr, 0.033 to 0.055% of Al, 0.0160 to 0.0300% of N, 0.001 to 0.009% of Ti, less than or equal to 0.0020% of O and the balance Fe and unavoidable impurities. Through a micro-alloying method, abnormal growth of austenite grains of gear steel in high-temperature vacuum carburizing is controlled and thus steel grain granularity is strictly controlled in a range of 7.0 to 8.0 grade and hardenability (J5mm) is stably controlled in a range of 32 to 42 HRC so that various performance requirements of common gear steel are satisfied. The high-temperature vacuum carburized gear steel contains simple alloy elements, has a low cost, allows stable and reliable process control, can be utilized for high-temperature vacuum carburizing, greatly reduces carburizing time, is environmentally friendly and saves energy.

Description

technical field [0001] The invention belongs to the field of alloy steel, and particularly relates to a high-temperature vacuum carburizing gear steel. The grain size of the steel before and after high-temperature vacuum carburizing is maintained at 7.0-8.0, the hardenability J5mm is stably controlled at 32HRC-42HRC, and the structure of the steel is stable. , stable performance. Background technique [0002] With the increasing environmental pollution and energy depletion, the high-temperature vacuum carburizing technology with environmental protection, energy saving, high performance and high efficiency has become the main direction of the development and application of international heat treatment technology in recent years. At present, the gas carburizing temperature commonly used at home and abroad is generally not higher than 930°C, while the high-temperature vacuum carburizing can be as high as 980°C or even 1000°C because of its oxygen-free treatment environment. Ac...

AI Technical Summary

Problems solved by technology

Existing studies have shown that B is an element that is very sensitive to hardenability, and small changes in B content will cause large fluctuations in hardenability. Therefore, adding B elements to gear steel is not conducive to narrowing the hardenability bandwidth of gear steel. Amplitude control

[0009] Chinese patent CN101603151A reduces the Ti content by increasing the Nb element, which solves the problem of contact fatigue life caused by a large amount of Ti inclusions, but the addition of Nb element also increases the production cost of the gear steel

[0010] Chinese patent CN101275204A discloses a CrMnTi gear steel. The Ti content is controlled at 0.010%-0.038%. It still has a relatively high Ti element content, and the possibility of inclusions is still relatively large, which is not conducive to the structure and performance of the steel.

However, the compound addition of Nb and V also increases the production cost of steel

[0012] To sum up, if the content of alloying elements is too low, it cannot meet the purpose of steel design and meet the requirements of the user's working conditions; if the content of alloying elements is too high, some performance indicators will be excessive, which will increase the cost of steel and waste limited resources.

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