Residual stress due to the stress of the workpiece during the manufacturing process, resulting in the inner member. In the absence of external force, the stress is present in equilibrium inside the object.
As can be seen from the concept, a residual stress value but does not refer to or referred to a distribution state of the residual stress field. Only the presence of residual stress or tensile stress, but the compressive stress exists in equilibrium tensile or compressive stress simultaneously. Elastic stress residual stress is, in theory, its value should not exceed the yield strength of the material.
Causes residual stress include:
1. ununiform distortion: plastic deformation after the load is removed after the deformation of the internal stress is formed;
2. thermal effect: the fast cooling process external cooling, internal cooling slowly, thereby rendering the external tensile stress, internal compressive stress presented; as well as thermal residual stresses cause the phase change like.
3. The effect of the stress generated by the chemical.
Sometimes beneficial residual stress (compressive stress typically), sometimes hazardous (usually a tensile stress), and these stresses is one of the key factors in many parts of life, especially those that are often subjected to fatigue and / or components used in the stress corrosion cracking environment.
Most of the time, the presence of residual stress, on the one hand reduces the strength of the workpiece, the workpiece and the deformation process defects such as cracking at the time of manufacture; on the other hand will release the natural process after production, the workpiece size changes or decreases the mechanical properties of fatigue strength, stress corrosion and the like.
There are many detection methods residual stress, wherein the X-ray diffraction method is recognized as the most accurate and reliable and convenient detection method, it is widely used.
X-ray diffraction is a technique may be used for non-destructive testing and destructive testing methods to compare the part of the stress. Measurement may be performed after each step and at the beginning and end of the process.
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Residual stresses, contact --CTI Chinese measurement test, Shijing Li 13556071774 (the same micro-channel number) [email protected]