carbide drill feeds and speeds chart. Complete reference tables for engineering decisions.
Complete reference tables and engineering data for tool steel heat treat. All values verified against ISO, ANSI, and manufacturer standards.
Tool steels achieve their final properties through controlled heat treatment. Hardening and tempering temperatures vary significantly between grades. This reference covers the critical temperatures for the most commonly used tool steels in machining and toolmaking.
O1 can be heat treated with a torch and oil quench followed by kitchen-oven tempering. A2 and D2 need a heat treatment furnace with temperature control (plus/minus 5 deg C) and protective atmosphere or stainless foil wrap to prevent decarburisation. H13 and M2 require high-temperature furnaces (1200+ deg C) and multi-stage preheating -- leave these to professional heat treaters.
Tempering between 250-400 deg C on many alloy steels causes "temper embrittlement" -- a loss of toughness. This is why H13 should always be tempered above 540 deg C. The secondary hardening peak (around 500-550 deg C) in alloy tool steels actually increases hardness slightly. Each grade has specific tempering temperature ranges that should be strictly followed.
Wrap the part in stainless steel tool wrap foil (309 or 321 stainless, 0.05 mm thick) with a small piece of paper or wood inside to consume residual oxygen. Seal tightly. This creates a protective atmosphere inside the envelope. Alternatively, use a controlled-atmosphere furnace with nitrogen or endothermic gas. Decarburisation removes carbon from the surface, softening it -- this cannot be recovered without removing the decarburised layer by grinding.
Identify your tool steel grade. Look up the austenitising (hardening) temperature and quenching medium. Temper at the temperature corresponding to your target hardness. For critical tooling, use a professional heat treater with vacuum furnace capability -- the consistency and quality assurance are worth the cost.
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