Red Sea Explorer blog Heat Treatment Services For Welding Metals

Heat Treatment Services For Welding Metals

When weld heat treatment services it is important that the materials are heated before and after the welding process to slow the cooling rate. This helps to maintain the integrity of the parent material and the weld. There are a number of heat treatment services that can be performed during or after the welding process including Pre Heating, Post Weld Heat Treatment and Tempering.

What are heat treatment services?

Pre Heating is a thermal treatment that can be applied before welding to raise the temperature of the parent material and deposited weld metal in order to retard the cooling rate and prevent formation of detrimental phases such as hydrogen embrittlement and cracking of the weld interface. Pre Heating can be achieved using oxy-gas flames, electric blankets, induction heating or other methods. It is important that the heating is uniform around the joint area. Intense non-uniform heating will cause higher residual stresses, distortion and metallurgical changes in the base material.

Post Weld Heat Treatment (PWHT) is a thermal process that is used to relieve the residual stresses introduced to the base and weld metals through forging, cold working, welding and other manufacturing processes. It is also a critical step in the prevention of Stress Corrosion Cracking (SCC). PWHT is achieved by heating the material uniformly to a temperature below its lower critical transformation temperature, holding it at this temperature for a period of time and then slowly cooling back to ambient temperatures.

PWHT should be done in accordance with applicable codes and standards. It should also be based on the expected service conditions and the likely mechanisms for failure of the welds.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Post