# Steel Heat Treatment Processes: Types, Temperatures and Purpose > Source: https://netray.co/tools/steel-heat-treatment-processes-reference > Publisher: Netray (netray.co), AI and integration engineering for ERP and manufacturing systems. > Section: Free Tools ## Short answer Quick lookup of common heat treatment processes with typical temperature ranges, cooling method and what each one is used for. ## Category manufacturing ## Industry Heat Treating ## Audience - Heat treat engineer - Metallurgist - Process engineer - Buyer ## Tool **Kind:** worksheet **Mode:** reference **Columns:** #### Process **Key:** process **Type:** text #### Applies to **Key:** applies **Type:** text #### Typical temp (deg C) **Key:** temp_c **Type:** text #### Cooling **Key:** cooling **Type:** text #### Purpose **Key:** purpose **Type:** text **Rows:** **Process:** Full annealing **Applies:** Steel **Temp c:** Austenitize about 30-50 above Ac3 (hypoeutectoid) **Cooling:** Slow furnace cool **Purpose:** Soften, refine grain, improve machinability **Process:** Process annealing **Applies:** Low carbon steel, cold worked **Temp c:** 550-700 **Cooling:** Air or furnace **Purpose:** Restore ductility after cold work **Process:** Spheroidize annealing **Applies:** High carbon and tool steel **Temp c:** Just below A1, about 680-760 **Cooling:** Slow **Purpose:** Form spheroidal carbides for machining and forming **Process:** Stress relieving **Applies:** Steel, cast iron, weldments **Temp c:** Steel 550-650, gray iron 510-565 **Cooling:** Slow cool **Purpose:** Reduce residual stress without changing structure much **Process:** Normalizing **Applies:** Steel **Temp c:** Austenitize about 850-920 **Cooling:** Still air **Purpose:** Uniform fine grain, refine forgings and castings **Process:** Hardening (quench) **Applies:** Medium and high carbon steel **Temp c:** Austenitize about 800-870 **Cooling:** Water, oil, polymer or air by grade **Purpose:** Form martensite for strength and hardness **Process:** Tempering **Applies:** Quenched steel **Temp c:** 150-650 **Cooling:** Air **Purpose:** Trade hardness for toughness, relieve quench stress **Process:** Austempering **Applies:** Steel, ductile iron **Temp c:** Hold in salt bath 260-400 **Cooling:** Isothermal then air **Purpose:** Bainite structure, toughness with strength, less distortion **Process:** Martempering **Applies:** Alloy steel **Temp c:** Quench to hold just above Ms **Cooling:** Hot oil or salt, then air **Purpose:** Reduce distortion and cracking before temper **Process:** Carburizing **Applies:** Low carbon and alloy steel **Temp c:** 880-955 **Cooling:** Quench then temper **Purpose:** Hard high-carbon case on a tough core **Process:** Carbonitriding **Applies:** Low carbon steel **Temp c:** 780-900 **Cooling:** Oil quench then temper **Purpose:** Thin hard case, lower temperature than carburizing **Process:** Gas nitriding **Applies:** Alloy and nitriding steels **Temp c:** 495-565 **Cooling:** Furnace or slow **Purpose:** Hard nitride case with little distortion, no quench **Process:** Induction hardening **Applies:** Medium carbon steel **Temp c:** Rapid surface austenitize **Cooling:** Spray quench **Purpose:** Local surface hardness on shafts, gears **Process:** Flame hardening **Applies:** Medium carbon steel **Temp c:** Torch heat of surface **Cooling:** Water or air spray **Purpose:** Local hardening of large parts **Process:** Subzero treatment **Applies:** Tool steel, carburized steel **Temp c:** Below minus 70 **Cooling:** Warm to ambient **Purpose:** Transform retained austenite, dimensional stability **Process:** Solution treatment (aluminum) **Applies:** 6061 and other heat treatable alloys **Temp c:** About 530 for 6061 **Cooling:** Water quench **Purpose:** Dissolve strengthening elements before aging **Process:** Artificial aging T6 (6061) **Applies:** Aluminum 6061 **Temp c:** 160-175 **Cooling:** Air **Purpose:** Precipitation hardening to T6 properties **Process:** Ferritizing anneal **Applies:** Ductile iron **Temp c:** About 700-900 depending on route **Cooling:** Slow or controlled **Purpose:** Convert pearlite to ferrite, raise ductility **Process:** Solution anneal (austenitic stainless) **Applies:** 300 series **Temp c:** 1010-1120 **Cooling:** Rapid cool or water quench **Purpose:** Dissolve carbides, restore corrosion resistance **Process:** Precipitation hardening (17-4PH H900) **Applies:** 17-4PH stainless **Temp c:** 480 for 1 hour **Cooling:** Air **Purpose:** Age to high strength after solution treatment **Notes:** Temperature ranges are typical practice for plain guidance. Actual cycles depend on grade, section size, equipment and the governing specification. Use the customer or industry spec (for example AMS or MIL) for any controlled work. ## Content **Intro:** Heat treat terms get mixed up on drawings and routings all the time. This reference lists the common processes, the temperatures they usually run at, how the part is cooled and the reason each one is used, so engineers, buyers and planners can speak the same language. **Sections:** #### How to use the table **Body:** Search for a process name or a material to filter the list. Each row shows what the process applies to, the typical temperature range in degrees Celsius, the cooling method and the purpose. Export to Excel to build a controlled list of heat treat operation names for your ERP routing, so every operation points to a single standard description. This is especially useful when a drawing note such as stress relieve or normalize needs to be translated into a work center and operation code. **Bullets:** - Use the purpose column to pick the right process - Compare cooling methods to understand distortion risk - Export operation names for ERP routing master data #### Softening versus hardening **Body:** Annealing, normalizing and stress relieving mostly soften or stabilize the part. Hardening followed by tempering makes it strong and tough. Case treatments such as carburizing and nitriding keep the core tough while giving a hard wear surface. For aluminum, the sequence is solution treat, quench and age. The drawing callout, such as T6 for aluminum or a Rockwell range for steel, tells you which sequence applies. Always check which side of the process is intended before quoting or scheduling. **Bullets:** - Normalizing is air cooled, annealing is furnace cooled - Tempering always follows hardening, never replaces it - Nitriding has no quench and so low distortion #### Common mistakes **Body:** People confuse normalizing with annealing, and the difference matters: normalizing cools in air and gives higher strength and a finer structure, annealing cools slowly and gives maximum softness. Another error is skipping a temper after quenching a high hardenability steel, which leaves a brittle part at risk of cracking. A third is using quench media that is wrong for the grade, such as water on an alloy that wants oil, which causes quench cracks. Record furnace class, load and cycle in the traveler so the result can be proven. **Bullets:** - Temper soon after quenching to avoid delayed cracks - Match quench medium to hardenability - Log cycle and furnace for traceability **Cta:** If heat treat operations are scattered across routings and vendor purchase orders, we can help standardize them in your ERP and connect certificates to lots. This reference needs no sign-up. **Faq:** #### What is the difference between annealing and normalizing? **Answer:** Both heat steel into the austenite range, but annealing cools slowly in the furnace for maximum softness, while normalizing cools in still air for a finer, somewhat harder and stronger structure. Normalizing is common after forging or casting to refine grain. #### What temperature is tempering done at? **Answer:** Tempering typically runs from about 150 to 650 deg C. Low temperatures keep high hardness for tools and bearings, while higher temperatures give more toughness for shafts and structural parts. The drawing hardness or the spec sets the final temperature. #### Why is nitriding used instead of carburizing? **Answer:** Nitriding runs at a much lower temperature, about 495 to 565 deg C, and needs no quench, so distortion is small. It suits finished or near finished parts. Carburizing gives a deeper case and suits gears and shafts that carry heavy loads. #### What is T6 temper for aluminum? **Answer:** T6 means the alloy was solution heat treated, quenched and then artificially aged. For 6061 that typically means solution treating near 530 deg C, quenching, then aging around 160 to 175 deg C, with times set by the specification. ## Search terms types of heat treatment processes, heat treatment temperature chart, annealing vs normalizing temperature, tempering temperature range steel, nitriding temperature, carburizing temperature, stress relieving temperature steel, t6 aging temperature 6061 --- Talk to an engineer: https://netray.co/contact?intent=erp_ai | Machine catalog: https://netray.co/agent/catalog.json