Hardening, tempering and annealing temperatures for O1, A2, D2, H13 and S7 tool steels, with soak times, quench media and the hardness-versus-temperature data needed to hit a target.
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.
Continue with closely related resources from the machining reference library.
Use the calculator freely. If the result points to a tooling or process problem, we can source the exact carbide tooling you need from vetted factories in China. Compare factory-direct pricing.
Before you commit to a spec, it helps to know what the market pays for it. These are real, publicly listed factory prices — not a quotation, and not a guess.
We source the tool families below direct from vetted Chinese factories, matched to the material and tolerance you just worked out. Every batch ships with its material certificate and dimensional record.
Explore more precision machining tools and calculators
Hardness is not the whole specification… Our guide covers why substrate grade decides tool life — and why a material certificate cannot answer a grain-size question.
We source carbide cutting tools from China for job shops. We do not own a factory, which is why we can quote your drawing against two or three plants that actually run your material.
Cutting formulas with the units worked through · Speed and feed starting points for all six ISO material groups · How to read a carbide grade past its ISO code. 12 pages.
Or send us a quote you already have — we will benchmark it free →