Application

Post weld heat treatment

We perform Post Weld Heat Treatment to retain material strength of the part after welding. By PWHT, one can control the hardness of the material and reduce the residual stress induced. Hence, after welding, one has to process the material through Post Weld Heat Treatment.

 

During the process engineers ensure that, the temperature do not drop below the specified degree. Apply PWHT method for the part at temperature up to 316°C. PWHT avoids Weld failures, susceptible brittle fracture and high cracking potential.

 

Benefits of Post Weld Heat Treatment

  • Hydrogen removal
  • Reduction of residual stresses
  • Corrosion resistance
  • Dimensional stability
  • Tempering
  • Enhanced ductile roughness

Post Weld Heat Treatment is carried out in Bogie Hearth Furnace and Chamber Furnace. Most common types of Post Weld Heat Treatment are Post Heating & Stress Relieving.

 

Post Heating

Hydrogen induced cracking is the common occurrence during welding. This is due to high levels of hydrogen diffuse into the material. The material after welding permeate hydrogen from the welded area. This PWHT process should start after welding and maintain a hot temperature for couple of hours. The temperature is based on the thickness and type of material used.

 

Stress Relieving

Once the welding process is complete, the material has enormous amount of residual stress. This leads to stress corrosion and hydrogen induced cracking. Hence, PWHT releases these stresses and cracking. The temperature is set to change as and when required.

 

Factors for applying PWHT process

  • Check on previous heat treatment & alloy systems
  • It may cause damage but essential for most of the materials