The document summarizes research on creep damage during stress relaxation in welded stainless steel components. The objectives are to quantify the effects of creep properties mismatch and weld geometry on creep deformation and damage, validate a state variable based damage assessment approach for 316H steel welds, and address monotonic stress relaxation damage like reheat cracking of welds. Activities include developing analytical models, performing FE analyses, assessing experimental techniques to measure continuum creep damage, and calibrating state variable based damage models with existing test data on 316H material.

1. Creep Damage during stress
relaxation in welded stainless
steel components
Solid Mechanics Research Group
Satyajit Dey
PhD Student

2. Research Motivation
• Creep deformation in welded joints not well understood
• Adequate justification required for the factor based approach in creep
damage assessment methods for weldments
• Welded component specific creep damage assessment procedures
required
• Address monotonic stress relaxation damage phenomena such as
reheat cracking of welds
Main project objectives
• Quantify effects of creep properties mismatch and weld geometry on
creep deformation and damage of weldments:
• Effects on Elastic Follow Up effect
• Effects on stress raising effects in the weld fusion zone
• Validate state variable based damage assessment approach for
316H steel welds

3. Research Activities
• Develop analytical models for welded components
• Perform FE analyses of reheat cracking of welds arising
due to creep relaxation of residual stresses
• Assess existing experimental techniques used to
measure continuum creep damage and creep strains
• Compare analytical results with existing experimental
results – benchmarking analytical models
• Calibrate state variable based damage models with
existing test data on 316H material and incorporate
stress and strain enhancement effects in the weld fusion
zone

4. Some Snapshots (S4 Weld Reheat Cracking)
Contra-rotating Wind
Turbine Generator
Novel Energy Supply Unit
Novel High Speed
Containment for a Generator
S4 Reheat Cracking model