The effect of TiN precipitated particles on the austenite grain and hardenability of 20CrMnTi gear steel

ABSTRACT

To study the effect of TiN precipitated particles on two end-quenching specimens of 20CrMnTi steel with different hardenability characteristics, the peripheral hardness of the samples is tested. The microstructures, austenite grain structures, characteristics of TiN particles are analyzed. The larger the grain size, the higher the martensite fraction and the higher the hardness. More uniform and more refined grains reduce the maximum peripheral hardness difference of end-quenched samples from 9.1HRC to 3.3HRC. The precipitation of as much fine TiN as possible in the solid phase plays an important role in obtaining more refined and more uniform austenite grains. TiN precipitates less during solidification and more in the solid phase in the sample with better hardenability, promoting grain refinement and more uniform peripheral hardness. In production, with a specific mass fraction of Ti, effectively inhibiting the precipitation of coarse TiN during solidification is the key to control narrow hardenability bandwidth for 20CrMnTi gear steel.

KEYWORDS:

• 20CrMnTi
• gear steel
• TiN
• hardenability
• solidification
• microstructure
• pinning effect
• austenite grain

Acknowledgements

The authors appreciate the Xining Special Steel Co. Ltd. for the technical help.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [Grant Numbers 51874034 and 51674024].