Gear Steel: A Core Necessity in Equipment Manufacturing

I. "The Cornerstone of Transmission" – Gear Steel

1. Definition
Gear steel is a general term for steel that can be used in the manufacturing of gears. After heat treatment according to usage requirements, this type of steel generally possesses good strength, hardness, and toughness, or exhibits surface wear resistance with a tough and impact-resistant core.

2. Classification
Based on carbon and alloy content, gear steel can be categorized into low-carbon steel such as Grade 20 steel, low-alloy steel such as 20Cr and 20CrMnTi, medium-carbon steel such as Grade 35 and Grade 45 steel, and medium-alloy steel such as 40Cr, 42CrMo, and 35CrMo.

According to alloy series, gear steel can be classified into Cr-Mn-Ti series, Cr series, Mn-Cr series, Cr-Mo series, Cr-Mn-B series, and Cr-Ni-Mo series.

China: Traditional gear steel grades follow the former Soviet standards, with the most commonly used being the Mn series and Mn-Cr series. The most representative grades are 20CrMnTi and 20CrMo. The national standards GB/T 3077-2015, GB/T 5216-2014, GB/T 33160-2016, and the gear industry association standard CGMA 001-2012 "Technical Conditions for Vehicle Gear Steel" specify the technical requirements for gear steel, among which GB/T 33160 primarily addresses gear steel for wind power generation.

Japan: Gear steel is subdivided according to practical applications, mainly consisting of Cr series, Cr-Mo series, and Ni-Cr-Mo series. For example, the Cr series (such as SCr415) is mostly used in transmission gears of small vehicles; the Cr-Mo series (such as SCM420) is applied in the drive and driven gears of small automobile rear axles (among which SCM822, with higher Mo content, is used for medium-sized vehicle rear axle drive and driven gears); the Ni-Cr-Mo series (such as SNCM415) is used in heavy-duty vehicles requiring high hardenability and core toughness. The Japanese standard JIS G4052 specifies the main technical requirements for gear steel.

US: For small vehicle transmissions, Mo steel 4023 is predominantly used. For medium-sized vehicle transmission gears and rear axle drive and driven gears, steels with lower Ni content, such as 8260 and 8720, are mainly employed. For heavy-duty vehicles, steels with higher Ni content, such as 4320, and those with higher Mo content, such as 8822, are primarily used, with some heavy-duty vehicles utilizing boron-containing 94B17. The US standards SAE J1268 and ASTM A304 specify the main technical requirements for gear steel. Germany: Primarily includes Mn-Cr series, Cr-Mo series, ZF series (Mn-Cr series with added B), Cr-Ni-Mo series, etc., such as 17CrNiMo6. The main technical requirements for gear steel are specified in the German standards DIN EN 10084 and DIN 17210.

3. Production Process
There are essentially two types of production process routes for gear steel in China:
(1) EF (or BOF) + LF (or VAD or RH) refining → ingot casting by mold → primary rolling (or forging) into blooms/billets → finishing by open-train or semi-continuous rolling mill → finishing → inspection and warehousing;
(2) UHP (Ultra High Power process for clean steel production) (or EBT eccentric bottom tapping electric arc furnace) + LF/VD refining → continuous casting of alloy steel square billets → finishing by (semi-)continuous rolling mill → finishing → inspection and warehousing.

II. Steady Production Growth and Quality Improvement, with Accelerating Concentration
The gear steel industry's production has maintained a steady growth trend for many consecutive years. According to statistics from the China Special Steel Enterprises Association, the crude steel production of gear steel by its key member enterprises reached 5.02 million mt in 2024, up 39.1% YoY compared to 2021. Against the backdrop of increasingly fierce competition in the low value-added steel market, top-tier enterprises are accelerating their breakthroughs into the "specialized, refined, distinctive, and innovative" track. Through measures such as full-process cost optimization, intelligent production line upgrades, and deep integration with end-use demand, they have achieved cost reduction and efficiency improvement, leading to continuous enhancement in the industry's development quality. Based on the current pace of capacity release and market demand forecasts, the crude steel production of gear steel by key member enterprises is expected to reach 5.6 million mt in 2025, up 11.6% YoY.

The concentration among gear steel producers is currently high. CITIC Pacific, Baowu Group, Shagang Group, Valin Group, and HBIS Group collectively hold a market share exceeding 50%. Besides these, there are also Ansteel Group and Jianlong Group, among others. Top-tier enterprises, leveraging their strengths in R&D capability, cost control, and stable customer resources, are expanding their scale through mergers and acquisitions, capacity replacement, and other means. Meanwhile, small and medium-sized enterprises, squeezed by multiple pressures including environmental protection thresholds, technological barriers, and fluctuations in raw material prices, are seeing their survival space continuously shrink, leading to business transformation or market exit. The industry pattern of "the strong getting stronger" is becoming increasingly evident. III. Stable Automotive Demand and Significant Industrial Cluster Effects
Gear steel is the core raw material for gear production, and gears, as indispensable key basic components in the mechanical industry, serve as the core transmission carriers for the vast majority of complete machinery equipment. The application scenarios of gear steel are extensive, and correspondingly, China's gear industry is primarily composed of three major segments: vehicle gears, industrial gears, and specialized gear equipment. Among these, vehicle gears account for 62% of the market share; industrial gears, comprising general-purpose and specialized gears, hold market shares of 18% and 12%, respectively; gear equipment accounts for 8% of the market share.

From the perspective of end-user demand structure, the automotive industry is the core consumption sector, accounting for over 50% and serving as the primary driver boosting gear steel production growth; followed by the machinery industry, with a share close to 30%; the remaining demand is distributed across sectors such as home appliances, medical, and rail transportation.

Regionally, domestic gear industrial clusters exhibit significant effects. Influenced by constraints such as transportation costs, supply cycles, and production coordination levels, China's gear industry participants are increasingly concentrating and standardizing regionally. Currently, the largest gear industrial cluster in China is located in east China, accounting for over 50% of the national gear market in terms of production and sales. This is followed by concentrations in the Beijing-Tianjin-Hebei, northeast China, and Sichuan and Chongqing regions. Among these, medium and large manual transmission gear products for automobiles are primarily situated in Changchun and Chongqing, while specialized, general-purpose, and heavy-duty gears are mainly distributed in Hebei, Zhejiang, Jiangsu, and other regions.

IV. Dual Drivers of Supply and Demand: Gear Steel Enters a New Phase of Simultaneous Growth in Quantity and Quality
Supply side, against the backdrop of deep involution in the steel industry, the entire sector is compelled to accelerate technological iteration and process breakthroughs, driving gear steel products toward high-end and performance-extreme development. Coupled with the ongoing enforcement of environmental protection checks and dual controls on energy consumption and energy intensity policies, small and medium-sized enterprises are gradually exiting or transforming, further accelerating industry consolidation and highlighting the capacity and technological advantages of top-tier enterprises. Demand side, the automotive industry remains the core pillar of gear steel consumption, with the rapid penetration of NEVs effectively offsetting the decline in demand for internal combustion engine vehicles. The engineering machinery sector, supported by dual drivers of domestic infrastructure gap-filling and overseas exports, is driving steady growth in gear steel demand through core models such as excavators, cranes, and loaders. Meanwhile, emerging manufacturing fields such as industrial robots and precision machine tools are rapidly rising, becoming new growth points for gear steel demand. In summary, the gear steel industry is entering a new phase of "simultaneous growth in quantity and quality," with high-end, customization, and green development being the core directions throughout the industry's evolution.