Heat Treatment Guide — Hardening & Tempering (with expected HRC)

Practical quick-reference for workshop engineers. Values are typical guidelines — final HRC depends on alloy chemistry, section size, quench medium and furnace control.

Quick Reference Tables

Click any table heading to jump to that section.

1. Carbon Steels (Low, Medium, High Carbon)

Material Hardening (°C) Quench Tempering (°C) Expected HRC
EN 8 / C45 800–830°C Oil 450–600°C 28–45 HRC
EN 9 / C55 810–830°C Oil 200–400°C 42–52 HRC
EN 19 / 4140 830–860°C Oil/Polymer 200–600°C 28–50 HRC
EN 24 / 4340 830–860°C Oil 200–600°C 38–55 HRC
C60 / EN 47 820–840°C Oil 200–450°C 45–55 HRC
High Carbon 0.9–1.0% (O1 type) 780–820°C Oil 150–250°C 55–62 HRC

2. Alloy & Tool Steels

Material Hardening (°C) Quench Tempering (°C) Expected HRC
D2 Tool Steel 1010–1040°C Air/Oil 150–550°C 54–62 HRC
H13 Hot Work Steel 1000–1030°C Air 500–650°C 42–52 HRC
O1 Oil-Hardening Tool Steel 780–820°C Oil 150–250°C 57–63 HRC
M2 HSS 1200–1230°C Oil/Pressure air 500–600°C 60–66 HRC
SKD11 (D2 equiv.) 1020–1040°C Air 150–550°C 58–61 HRC

3. Stainless Steels

Material Hardening (°C) Quench Tempering (°C) Final HRC
410 Stainless 980–1010°C Oil/Air 150–400°C 35–48 HRC
420 Stainless (Cutlery) 980–1050°C Oil/Air 150–250°C 48–55 HRC
440C Stainless 1040–1070°C Oil/Air 150–200°C 56–60 HRC

4. Case Hardening Steels (After Carburizing/Nitriding)

Material Carburizing Temp Hardening Temp Quench Tempering Case Hardness
EN 353 900–930°C 820–860°C Oil 150–200°C 58–62 HRC
EN 36 / 9310 900–950°C 800–840°C Oil 150–200°C 58–62 HRC
20MnCr5 900–930°C 820–860°C Oil 150–200°C 58–62 HRC

5. Spring Steels

Material Hardening (°C) Quench Tempering (°C) Final HRC
EN 45 830–860°C Oil 450–550°C 40–50 HRC
65Mn / SUP9 820–840°C Oil 300–500°C 42–52 HRC

Notes & Guidance

  • Values are typical workshop guidelines. Final HRC depends on alloy composition, section size, furnace accuracy, and quench method.
  • Always use a calibrated thermocouple and hardness tester for production control.
  • For critical parts, run a test coupon of representative section and perform microstructure and hardness verification.