en.Wedoany.com Reported - Hyundai Steel and Hyundai Motor have jointly developed a new-generation high-durability gear material for hybrid transmissions, addressing the contradiction between low carburization under high torque and cost control. This technology has won the 26th IR52 Jang Young-sil Prize in 2026.
As demand for hybrid electric vehicles (HEVs) as a transitional solution for electrification in the automotive market grows, competition to develop more efficient and powerful drive systems is intensifying. Hybrid vehicles must operate smoothly and powerfully in complex urban roads and highway conditions, requiring core components of the drive system to withstand extreme torque and heat. To meet these requirements, the aforementioned gear material was developed, aiming to surpass overseas competitors in durability and price competitiveness.
This technology is specifically applied to the "rear gear" within the transmission, which directly reduces engine and motor power while increasing torque. The new-generation hybrid transmission features a 31% increase in torque compared to the original design, but its overall length is reduced by 20 mm, exacerbating load and heat generation issues for components.
Early approaches increased durability by raising chromium and silicon content, but this formed a dense oxide layer on the surface, causing a "low carburization phenomenon" that hindered carbon penetration and led to quality degradation. Overseas automakers addressed this by maximizing nickel content, but the significant cost increase became an obstacle. The research team resolved this technical contradiction by determining the optimal threshold for alloy composition to suppress low carburization while adding vanadium to strengthen the microstructure.
The new material is characterized by a heat treatment process that increases the density of fine reinforcing particles within the metal by approximately three times compared to the original level. This significantly improves resistance to intense friction and heat during gear meshing: fatigue life from gear surface wear increases by 23%, and the load-bearing life without gear tooth fracture increases by 10%. This material has been installed in the large SUV "Palisade Hybrid" and has passed real-vehicle durability tests exceeding 100,000 km without any issues. Additionally, by reducing the use of expensive raw materials, material costs are 17% lower than those of overseas competitors.
Products manufactured using this material will be sequentially applied to Hyundai Motor and Kia's premium hybrid vehicles and EREV (Extended Range Electric Vehicle) product lines. The company expects that, starting with sales of 350 million KRW last year, annual sales will exceed 1.3 billion KRW by 2029 as the global hybrid vehicle market expands. Hyundai Steel Special Steel Development Team Senior Researcher Hong Seong-min stated that overcoming material limitations while convincing partner companies and establishing optimal heat treatment conditions through mass production scale testing were core challenges, and the close collaboration between Hyundai Steel and Hyundai Motor research teams ultimately met the stringent standards.
