H-shaped steel with guaranteed hardenability for structural use

Supported standards JIS G4052
  • SAE, ASTM and EN standards are also supported.
Names of steel types SMn420H - SMn443H, SMnC420H - SMnC443H, SCr415H - SCr440H, SCM415H - SCM822H, SNC415H - SNC815H, SNCM220H - SNCM420H
Supported standards AICHI
Names of steel types AG20, SCMB21, SCM25M, SCM20Nb

Product catalog


Type of steel/Chemical composition

Type Type of steel Main chemical components
representative values (%)
C Si Mn Cr Mo Other
①Pitting resistant steel AG20 0.20 0.8 0.6 0.5 0.5 Additives
②High strength cold forged gear steel SCMB21 0.21 Low 1.2 1.1 0.16
③High strength gear steel SCM25M 0.25 Low 0.8 1.1 High
④Coarse grain prevention steel SCM20Nb 0.20 0.25 0.8 1.1 0.16
Alloy ⑤Low-Mo case hardening steel 0.20 Low Adjusted -


Type of steel Characteristics Applications
①Pitting resistant steel AG20 High strength gear steel achieving both gear pitting fatigue strength and bending fatigue strength improvements Gears in high rotation/high surface pressure specification environments (planetary, gears, etc.)
②High strength cold forged gear steel SCMB21 Improve extremely low cycle fatigue strength and high strength gear steel with excellent cold forging characteristics Gears requiring impact fatigue strength (differential gears, etc.)
③High strength gear steel SCM25M
  • High strength large carburized parts
  • Shorter carburizing times with excellent carburizing effect characteristics
Large gears/shafts (Hypoid gears, etc.)
④Coarse grain prevention steel SCM20Nb Reduces coarsening of crystal grains during hot carburizing at 1000℃ or higher Parts with reduced carburizing times by high temperature carburizing
⑤Low-Mo case hardening steel Mo-less for strength characteristics equal to SCM420 and processing characteristics equivalent to SCr420 Carburized parts using SCM420


We provide steels responding to various needs of high strength, carburizing time reduction and alloy-savings.

Improved gear fatigue strength enables higher-capacity, reduction in size, weight and component count of units.
Reducing carburizing time allows the reduction of takt time, cost and CO2 emissions.
Alloy-savings reduce resource risks and cost.

Major applications

Variable gears, counter gears, differential gears, input/output shafts, inner/outer races
Construction machineries:
Gears, pinions, cylinder shafts

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