IntermediateTopic 72 of 106Engineering Mechanics
Residual stress
Stresses that remain in a part without external load, from welding or machining.
In depth
Residual stresses remain after processing: welding, casting, rolling, quenching and machining. Tensile residual stresses at surfaces reduce fatigue life; compressive ones (shot peening, nitriding) help. They are measured by X-ray diffraction or hole drilling.
Key points
- Self-equilibrating over a section
- Relieved by annealing
- Cause distortion on machining
ExampleWelded joints may carry residual tensile stress close to yield.
Residual stress from welding, casting and machining stays in the part without load, and it can cause distortion or early cracking.
What is Residual stress?
Stresses that remain in a part without external load, from welding or machining.
Why is it important to understand residual stress?
Residual stress from welding, casting and machining stays in the part without load, and it can cause distortion or early cracking.
How does shot peening help?
It introduces compressive residual stress at the surface, which resists crack opening and improves fatigue life.
Can residual stress be removed?
Yes, by stress relief heat treatment or by controlled machining sequences, though this may affect the material properties.
How is Residual stress used in practice?
Typical applications include explaining why a welded plate warps after cooling, choosing a shot-peening treatment to add compressive surface stress and predicting the cracking of a quenched steel part after heat treatment.
What should I learn before Residual stress?
Study "Plasticity and yielding" first (topic 71 of 106 in Engineering Mechanics). It covers the groundwork this topic builds on.
What are the key points of Residual stress?
Self-equilibrating over a section. Relieved by annealing. Cause distortion on machining.
Can you give an example of Residual stress?
Welded joints may carry residual tensile stress close to yield.
What comes after Residual stress?
The next topic is "Simple harmonic motion", which builds directly on this one.
How difficult is Residual stress?
It is classed as Intermediate in Engineering Mechanics (topic 72 of 106). It is an intermediate topic. Work through the beginner topics in Engineering Mechanics first.