Industries

• Marine
• Construction
• Pressure Vessels

Related Processes

Stress Relieving

Solution Annealing

Common Alloys

• Carbon Steels e.g. 1018, 1045
• Structural Steels e.g. A108, A572
• Alloy Steels e.g. 4140, 4330, 4340
• Stainless Steels e.g. 304, 316, 17-4
• ​Superalloys e.g. Haynes, Hastelloy

TMT Equipment/Variations
A standard post weld heat treatment will involve heating a weldment and holding it below the critical temperature and then slowly cooling it.  Care must be taken for hardened materials to not exceed the original tempering temperature which would decrease the strength.    For critical weldments, a process with specified heating and cooling rates may be required per the applicable standard.  Additionally, load thermocouples may be required.  Some welds on stainless steels and superalloys may require a solution annealing treatment.

Applications

• Post weld heat treatment can reduce subsequent dimensional changes by allowing a controlled redistribution of residual stresses.  This may cause some movement of parts during the process as stresses are relieved, but will reduce the overall effects of residual stresses
• Some welds will experience hardening in the fusion zone of the weld due to the rapid solidification of the weld.  Higher carbon materials and filler rods will be  most effected.  In order to increase the toughness of the weld a post weld heat treat will effectively temper the hardened area
• As the weld area is solidifying and cooling, unfavorable stress states can be formed due to the thermal gradients across the weldment.  This can lead to both dimensional and mechanical property deficiencies.  Post weld heat treating will allow the stress states to redistribute, lessening that effect.

Associated Specs/Standards

• AWS D1.1, D1.2, D1.5
• ASME B31.3, BPVS Section VIII, Section I, UCS 56

What To Consider When Specifying

• Material
• Heat Treat State
• Specification (if required)

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Have more technical questions?  Contact a TMT engineer here.