A new energy automobile steering pinion shaft steel and a manufacturing method thereof

By using Al-Nb microalloying and controlled rolling and cooling processes to prepare steel for steering gear shafts in new energy vehicles, the challenges of high-temperature carburizing and cold forging have been solved, enabling the manufacture of highly efficient and energy-saving steering gear shafts that meet the performance requirements of new energy vehicles.

CN122235581APending Publication Date: 2026-06-19JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
JIANGYIN XINGCHENG SPECIAL STEEL WORKS CO LTD
Filing Date
2026-03-19
Publication Date
2026-06-19

AI Technical Summary

Technical Problem

Existing technologies struggle to provide a steel for steering gear shafts in new energy vehicles that can withstand high-temperature carburizing at 980℃, has fine grain size, high purity, low hardness, good uniformity, and can be directly cold-forged. Furthermore, traditional processes are energy-intensive and have significant carbon emissions.

Method used

By employing Al-Nb microalloying strengthening, and through precise control of chemical composition and controlled rolling and cooling processes, AlN, NbC, and NbN precipitates are formed to pin grain boundaries. Combined with high-vacuum degassing and protective casting, steel for steering gear shafts of new energy vehicles with uniform microstructure is prepared, meeting the requirements of high-temperature carburizing and cold forging.

Benefits of technology

It achieves a grain size ≥ 7, B-class inclusion grade ≤ 0.5, and hardness ≤ 180HBW after high-temperature carburizing of steel at 980℃, with good microstructure uniformity, and can be directly cold forged, reducing energy consumption and carbon emissions, and is suitable for the high-speed and high-load working conditions of new energy vehicles.

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Abstract

This invention discloses a steel for steering gear shafts in new energy vehicles and its manufacturing method, belonging to the field of metallurgical technology. The steel, by weight percentage, contains C: 0.13~0.18%, Si: 0.15~0.30%, Mn: 0.65~0.90%, Cr: 0.95~1.20%, Al: 0.010-0.030%, Nb: 0.020~0.040%, N: 0.01-0.015%, Ti≤0.002%, [O]≤15ppm, with the remainder being Fe and impurities. The manufacturing method includes smelting, continuous casting billet heating, intermediate billet rolling, finished product heating and rolling, and cooling. This invention utilizes an Al-Nb-N microalloying synergistic refinement system, combined with a two-stage hot rolling and stepped slow cooling process, to enable steel to withstand high-temperature carburizing at 980℃. The austenite grain size across the entire cross-section is ≥7, B-type inclusions are ≤0.5, hardness is ≤180HBW with a range ≤10HBW, and the microstructure is uniform ferrite + pearlite, allowing for direct cold forging. The carburizing time is shortened by 50%, reducing energy consumption and carbon emissions. The steel exhibits excellent mechanical properties, making it suitable for the high-speed, high-load conditions of new energy vehicles. The process is stable and suitable for industrial production.
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