M42 Overview M42 is a high-cobalt high-speed steel designed for demanding cutting applications where high hardness, hot hardness and wear resistance are required. Chemical Composition C Cr W Mo V Co 1.05 – 1.15 3.50 – 4.50 1.00 – 1.50 9.00 – 10.00 1.00 – 1.25 7.50 – 8.50 Heat Treatment Controlled preheating.Austenitizing generally around 1150–1200°C.Controlled quenching.Multiple tempering cycles. Mechanical Properties Typical hardened hardness: 65–68 HRC.Excellent hot hardness.High wear resistance.Excellent cutting-edge retention. Equivalent Grade AISI: M42DIN: 1.3247DIN: HS2-9-1-8JIS: SKH59 Applications DrillsTapsMilling cuttersReamersBroachesSaw bladesThreading toolsCutting tools for hardened and difficult-to-machine alloys Available Forms Round barsFlatsSquares