How is residual stress relieved?
Post-weld heat-treatments are often used to relieve or redistribute the residual stresses in a welded object. From a mechanical perspective, techniques such as shot peening, cold rolling, and stretching can be applied to achieve the desired effect.
Is compressive residual stress good?
Compressive residual stress can have a very positive impact on fatigue performance because it acts to resist the applied tensile stress as it holds the crack faces shut, minimizing damage. To take advantage of this concept many compressive residual stress surface treatments have been developed.
How does residual stress increase strength?
This layer remained elastic longer than adjacent layers during tension, producing high hetero-deformation induced stress to increase strength and enhancing work hardening even after the disappearance of the compressive stress to increase ductility.
What is residual stress in casting?
Residual stresses are developed during the solidification process due to the temperature gradients between different parts of casting or due to the mechanical constraints imposed by the mold during shrinkage of the cast metal and volumetric change and transformation plasticity associated with the solid state phase …
What causes residual stress?
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.
Why residual stress is important?
Residual stresses have various effects on the performance of materials. Fatigue, stress corrosion cracking, failures, distortion, structural stability are the common effects. Residual stresses often cause costly hidden problems which effects will be seen during the service life of the components.
What is an example of compression stress?
Compressional stress is when a rock is pressed together into itself, like when crust movements cause two rocks to squeeze another one between them. Another example is when mountains are formed at a convergent boundary, like the Rocky Mountains. Press your hands together again.
Are residual stresses always harmful?
Residual stresses can be beneficial or detrimental, depending on whether the stress is tensile or compressive. Tensile residual stresses can be large enough to cause component distortion or cracking. Surface residual compressive stresses are generally helpful because they reduce the effects of applied tensile stresses.
What are sources of residual stresses?
Residual stresses arise from a number of sources and can exist in the unprocessed raw material, during manufacturing processes involving material deformation, heat treatment, machining or processing operations which transform the shape or change the properties of a material or can also arise from in-service loading ( …
What methods of determination of residual stresses do you think are the most effective?
Stripping is one of the most well-known methods for measuring the residual stress inside a workpiece. The accuracy of the traditional strain gauge method for measuring the internal residual stress is generally 30–50 MPa because of the influence of the strain gauge itself.
Are residual stresses harmful?
Harmful residual stress can lead to stress corrosion cracking, distortion, fatigue cracking, premature failures in components, and instances of over-design.
What fault is caused by compressional stress?
Reverse fault—the block above the inclined fault moves up relative to the block below the fault. This fault motion is caused by compressional forces and results in shortening. A reverse fault is called a thrust fault if the dip of the fault plane is small.