What are residual stresses and how are they caused

All the stresses that exist in materials are termed residual stresses.

Residual stresses can originally exist in a component and naturally add to the stresses induced by applied loads; they also can appear without the application of any external load.

Residual stresses limit the loading capacity and the safety of mechanical components during operation and in some applications it is necessary to be able to quantify these stresses.

Residual stresses can be caused by the following main factors:

  • non-uniform heating or cooling of a component during manufacturing and fabricating processes, like casting, welding, molding, heat treatment
  • machining processes to remove shavings or plastic deformation, like turning and forging
  • through or surface heat treatments, like tempering or welding
  • sand-blasting or shot-peening

SINT Technology  produced and developed the Restan-MTS3000 system, an automatic device for measuring residual stresses by the hole-drilling strain-gage method, in accordance with the ASTM E837 standard.

The MTS3000 is able to measure the residual stresses into METALS and other kinds of materials, both in the lab and on site.

 

Restan MTS3000: Residual stress measurement system

Restan MTS3000 is an automatic system for measuring residual stresses by the hole drilling method.

The system has been produced and developed by SINT Technology and it consist of an optical-mechanical system with an electronic control unit, a control software and a reprocessing calculation software EVAL. The complete measuring chain is fully compliant to the ASTM E837-13 standard.

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Main strain gage methods used for measuring residual stresses

Main strain gage methods used for measuring residual stresses

The main strain gage methods used for measuring residual stresses are:

 

  • Sachs’ boring-out method
  • Layer removal and sectioning
  • Contour method
  • Ring core method
  • Hole drilling strain gage method.

Measurement of Residual Stresses Brochure