New energy automobile high-hardenability gear steel bar and manufacturing method thereof

Through Nb and Ti composite microalloyization technology and high-temperature carburizing technology, the problem of grain growth of gear steel during high-temperature carburizing is solved, and high-strength, toughness and high hardenability gear steel materials are achieved, meeting the needs of new energy vehicles and have energy-saving and emission reduction effects.

CN120384248APending Publication Date: 2025-07-29JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
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Patent Information

Application Number
CN202510331492.0
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2025-03-20
Publication Date
2025-07-29

AI Technical Summary

Technical Problem

Existing gear steel materials are prone to grain growth and mixed crystal structure during high-temperature carburization, resulting in a reduced fatigue life and cannot meet the requirements of new energy vehicles for high strength and toughness and high hardenability.

Method used

The Nb and Ti composite microalloyization technology is used to form fine Nb(C,N) and (Ti,C,N) particles by adding Nb and Ti elements to prevent the growth of austenite grains, and nitrides are formed by combining Ti with N to improve hardenability. Combined with high-temperature carburizing technology, the carburizing temperature is controlled at 980℃.

Benefits of technology

The grain size of gear steel is maintained at level 5 or above under high temperature carburization conditions of 980℃, shortening the carburization time, improving hardenability, meeting the requirements of new energy vehicles for high strength and toughness, and saving energy and emission reduction.

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Abstract

The invention relates to a high-hardenability gear steel bar for a new energy automobile and a manufacturing method of the high-hardenability gear steel bar. The high-hardenability gear steel bar comprises the following chemical components in percentage by mass: 0.17-0.25% of C, less than or equal to 0.37% of Si, 0.50-0.90% of Mn, 0.85-1.25% of Cr, less than or equal to 0.025% of P, less than or equal to 0.030% of S, less than or equal to 0.30% of Cu, 0.02-0.06% of Ti, 0.02-0.05% of Al, less than or equal to 0.30% of Ni, 0.15-0.45% of Mo, 0.0005-0.0020% of B, 0.020-0.080% of Nb, less than or equal to 0.0030% of Ca, 0.0090-0.0150% of N, less than or equal to The production and manufacturing process comprises the steps of converter treatment, external refining, vacuum degassing, continuous casting, continuous rolling, shearing or saw cutting, stack cooling and finishing flaw detection. According to the invention, fine Nb (C, N) and (Nb, Ti) (C, N) particles are precipitated by microalloying Nb and Ti, the growth of crystal grains is effectively inhibited, and meanwhile, the hardenability of the material is improved by adding a proper amount of B element. According to the invention, Nb, Ti and B are adopted for composite microalloying at the same time, so that the fine-grain and high-hardenability gear steel material is obtained.
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