## What is meant by residual stress?

Residual stresses can be defined as stress fields that exist in the absence of any external loads and are the result of any mechanical process which can cause deformation.

### What are the types of residual stresses?

Residual stresses can be used to benefit or hinder the performance of a component during operation by placing the material in either a compressive or tensile stress state. There are three types of residual stresses within a material: Type-I, Type-II, and Type-III.

#### How is residual stress measured in steel?

Hole drilling is the most commonly used stress relaxation technique for measuring residual stresses. Stressed material is removed by drilling a small blind hole in the area of interest and the material around the hole spontaneously finds a new stress equilibrium.

Why do we need to study residual stress of steel?

Controlling the type and magnitude of residual stress is important for applications in which components will be exposed to fatigue or stress corrosion cracking conditions or if the residual stresses are large enough to cause component deformation or cracking.

What are the main causes of residual stresses?

WHAT CAUSES RESIDUAL STRESS? Residual stresses are generated, upon equilibrium of material, after plastic deformation that is caused by applied mechanical loads, thermal loads, or phase changes. Mechanical and thermal processes applied to a component during service may also alter its residual stress state.

## How do you calculate residual stress?

Residual stresses are determined from the diffraction data by calculating the strain from the diffraction peak positions. The width of the diffracted peak is affected by micro stresses and imperfections in the crystal structure (i.e. dislocations, plastic deformation, etc.).

### How does residual stress increase strength?

Tensile residual stresses at the component surfaces after quenching, increase the effective net stress range and the mean stress during fatigue loading. This accelerates the fatigue crack initiation and increases the fatigue crack propagation rate.

#### How residual stress is calculated?

How does residual compressive stress work?

In toughened glass, compressive stresses are induced on the surface of the glass, balanced by tensile stresses in the body of the glass. Due to the residual compressive stress on the surface, toughened glass is more resistant to cracks, but shatter into small shards when the outer surface is broken.

What causes tensile residual stress?

Tensile residual stresses are usually the side effects of production such as in aggressive grinding which causes crack growth. They can also be introduced with shrinking, fitting, bending, or torsion.