Why is stress relieving required after welding?

Welding introduces high residual stresses due to uneven heating and cooling. Stress relieving prevents cracking, distortion, and improves service life.

What temperature is used for stress relieving steel?

For mild and carbon steel, stress relieving is typically done between 500°C and 650°C depending on material grade and thickness.

Does stress relieving increase hardness?

No. Stress relieving mainly reduces residual stress and does not significantly increase hardness or strength.

What Is the Stress Relieving Process?

Q: What is the stress relieving process?

Stress relieving is a heat treatment process where metal is heated below its critical temperature and slowly cooled to reduce internal residual stresses without changing mechanical properties.

Stress relieving heat treatment is a critical process used by every professional heat treatment company to reduce internal stresses caused during welding, machining, forging, or cold working.

What Is Stress Relieving?

Stress relieving is a controlled heat treatment process where metal components are heated to a temperature below their critical transformation point, held for a defined time, and then slowly cooled. The aim is to eliminate residual stresses without altering the material’s microstructure.

Why Do Residual Stresses Occur?

Welding and fabrication
Machining and cutting operations
Cold working processes
Casting and forging

Purpose of Stress Relieving Heat Treatment

Reduce internal residual stress
Improve dimensional stability
Prevent cracking and distortion
Enhance fatigue life
Improve machining performance

Stress Relieving Temperature Range

Material	Temperature Range
Mild Steel / Carbon Steel	500°C – 650°C
Alloy Steel	550°C – 700°C
Stainless Steel	400°C – 600°C
Cast Iron	500°C – 600°C

Stress Relieving Process Steps

Step 1: Pre-cleaning of components

Step 2: Slow controlled heating

Step 3: Soaking at temperature (1 hour per 25 mm thickness)

Step 4: Furnace cooling

Difference Between Stress Relieving and Annealing

Parameter	Stress Relieving	Annealing
Purpose	Reduce residual stress	Soften material
Temperature	Below critical	Above critical
Hardness Change	Minimal	Significant

Applications of Stress Relieving

Pressure vessels and boilers
Welded structures
Shafts, gears, and flanges
Machine frames and heavy fabrication

The stress relieving process is an essential part of professional heat treatment services. It ensures component reliability, dimensional accuracy, and long service life. For critical applications, choosing an experienced heat treatment company for stress relieving is vital.