Heat Treatment - Custom CNC Machining Services for Precision Parts | Guangzhou Precision Machining Co., Ltd.

Common Heat Treatments | Heat Treatment Guide

Heat treatment is a process that alters the internal structure of metal materials through controlled heating, holding, and cooling to achieve desired mechanical properties. Proper heat treatment can significantly improve hardness, strength, wear resistance, toughness, and elasticity. Below is a list of common heat treatment processes for CNC machined and sheet metal parts, organized by process type.

Bulk Heat Treatment (for Structural Steel, Tool Steel)

Process	Applicable Materials	Key Benefits	Typical Applications
Annealing	Carbon steel, alloy steel, tool steel	Lowers hardness, removes stress, improves machinability	Blank preprocessing, castings/forgings
Normalizing	Carbon steel, alloy steel	Refines grain, adjusts hardness	General structural parts
Quenching	Carbon steel, alloy steel, tool steel	Significantly increases hardness & wear resistance	Shafts, gears, molds
Tempering	Quenched steel	Removes quenching stress, adjusts hardness/toughness	Nearly all quenched parts
Quenching + High Tempering	Medium carbon steel, alloy steel	Good combination of strength & toughness	Main shafts, connecting rods, bolts

Surface Heat Treatment (heats only the surface layer)

Process	Applicable Materials	Key Benefits	Typical Applications
Induction Hardening	Medium carbon steel, alloy steel	Hard surface, tough core	Gear teeth, journals, rails
Flame Hardening	Medium carbon steel, cast iron	Surface hardening for large parts	Large gears, rolls
Laser Hardening	Various steels, cast iron	Precise positioning, minimal distortion	Mold guide surfaces, precision parts

Chemical Heat Treatment (alters surface composition)

Process	Applicable Materials	Key Benefits	Typical Applications
Carburizing	Low carbon steel, low alloy steel	Hard surface, tough core	Gears, shafts, cams
Nitriding	Alloy steel containing Al/Cr/Mo (e.g., 38CrMoAl)	Very high surface hardness, wear resistance, minimal distortion	Precision lead screws, molds, valves
Carbonitriding	Low carbon steel, alloy steel	Higher hardness & wear resistance than carburizing	Small gears, pins, fasteners
Nitrocarburizing	Various steels, cast iron	Improves wear & scuffing resistance	Molds, cylinder liners, crankshafts

Heat Treatment for Non-Ferrous Metals (Aluminum, Copper Alloys)

Process	Applicable Materials	Key Benefits	Typical Applications
Solution Treatment	Aluminum alloys (2xxx, 6xxx, 7xxx), copper alloys	Increases strength & hardness	Aerospace structural parts, precision components
Aging	Aluminum alloys, copper alloys	Precipitation hardening, further improves hardness & stability	7075 aluminum parts, beryllium copper
Annealing (Softening)	Aluminum alloys, copper alloys	Removes work hardening, improves formability	Cold-worked sheets, copper bars

Selection Guide (Quick Reference)

Requirement	Recommended Process	Applicable Materials
Improved machinability (lower hardness)	Annealing	High carbon steel, tool steel
Low cost, general strength	Normalizing	Carbon steel, low alloy steel
High hardness & wear resistance	Quenching + Low Tempering	Tool steel, bearing steel
High strength + good toughness	Quenching + High Tempering	Medium carbon steel, alloy steel
Hard surface + tough core	Carburizing + Quenching + Tempering	Low carbon steel, low alloy steel
Very high surface hardness, no distortion	Nitriding	Alloy steel with Al/Cr/Mo
High strength for aluminum alloys	Solution + Aging	2xxx, 6xxx, 7xxx aluminum

Not sure which heat treatment your parts need?

The choice of heat treatment depends on material, working conditions (impact, wear, fatigue), and cost budget. Our engineering team can provide free recommendations on heat treatment processes.