Reheat Cracking
Definition
Intergranular cracking in the heat-affected zone of welds in certain alloy steels during post-weld heat treatment or early elevated-temperature service, caused by concurrent carbide precipitation embrittlement and residual stress relaxation.
- Location
- Heat-affected zone of welds
- Alloy susceptibility
- Certain alloy steels
- Trigger
- Post-weld heat treatment or early elevated-temperature service
- Mechanism
- Carbide precipitation embrittlement combined with residual stress relaxation
Common questions
How does reheat cracking differ from ordinary hydrogen cracking in welds?+
Hydrogen cracking typically appears shortly after welding while the joint cools, driven by dissolved hydrogen and residual stress, whereas reheat cracking appears specifically during a later reheating step, whether post-weld heat treatment or early service at elevated temperature, and is driven by carbide precipitation weakening the grain boundaries as residual stress relaxes.
Why does reheat cracking matter in a failure investigation of welded pressure equipment?+
Because it develops intergranularly and can be subtle on visual inspection, a reheat crack can go undetected until it propagates to failure in service, so investigators examining a weld failure in susceptible alloy steels specifically check the heat-affected zone microstructure and stress history for the classic signature of carbide precipitation along grain boundaries.
Related terms
- Creep
- Time-dependent plastic deformation of a material under sustained stress at elevated temperature, occurring at stress levels below the conventional yield strength.
- Grain-Boundary Sliding
- Relative motion of adjacent grains along their shared boundary, a key deformation mechanism at elevated temperature that opens voids at triple points...
- Hot Corrosion
- Accelerated degradation of a superalloy or coated turbine component by molten sulfate or vanadate deposits that flux and dissolve the protective oxide...
- Larson-Miller Parameter (LMP)
- A temperature-time combination parameter T(C + log t_r) used to correlate and predict rupture life across different temperature-stress combinations for a given...
- Minimum Creep Rate
- The steady-state strain rate during secondary creep, the single most important material parameter for structural life assessment under creep conditions.