KAL CAP Oil Hardening Tool Steel (AISI01 / SKS3)

Equivalent Grade of KAL CAP

StandardASTM A681DIN EN ISO 4957JIS G4404

Typical Saarloha Chemical Composition



  • Good machinability
  • Good dimensional stability during hardening treatment
  • Good combination of high surface hardness and toughness after hardening and tempering furnace cool at a rate not exceeding 28°C per/ hour to 550°C, then air cool. Annealed Hardness ~ 200-210 HBW. Stress relief: Heating slowly to 660-680°C, hold as per 1″ per 30 mm, then cool in still air.


Pre-heating: Heat to 600-650°C, equalize and heat to 800-815°C at the rate 100°C/1 hr max, soak for 30 minutes per inch of thickness and quench in warm oil.

Tempering: Temper immediately after hardening in range of 300 to 450° C for 2 hours per inch of thickness, air cool.

Normally oil hardening steels need to be single tempered only; however, double tempering may sometimes be preferred.


KAL CAP steels are mainly used for short run tooling like for cold forming dies, blanking dies, and cutting tools operating at ambient temperature.

Blanking, forming, and trim dies, gages, slitting cutters, punches, bolster dies, knock-out pins, thread roll dies, bending dies, plastic mold dies, shims, cams, machine ways, stamps, machine parts, jigs, cutter templates, swaging dies, etc.