welding cover picture
June 5, 2018

Stresstech Bulletin 15: Residual Stress in Welding

Modern industry has many requirements like cost efficiency, durability, lightness of manufactured parts and eco-friendliness to name a few. With these requirements in mind it’s crucial to have deep understanding of the manufacturing process and how it affects the finished part. Residual stress is one physical property that is becoming more crucial as the requirements and quality of manufacturing process grow.

shot peening residual stress cover
April 4, 2018

Stresstech Bulletin 14: Shot Peening Residual Stresses

Cold working causes plastic deformation that creates residual stresses. The degree and sign of the residual stress depend on degree and type of the working process. Shot peening is a cold working process in which the surface of a component is peened with small spherical balls called shots. The process induces plastic deformation on the surface, relieves surface tensile stresses and introduces beneficial compressive residual stresses. Shot peening is a similar process with surface rolling, both deform the surface plastically to develop a compressive residual stress depth profile.

types of residual stress cover
March 15, 2018

Stresstech Bulletin 13: Types of Residual Stresses

Residual stresses are spontaneously in equilibrium as tensile residual stresses (detrimental) and compressive residual stresses (beneficial). For example, a surface formed in tensile stresses will comprise compressive residual stresses, and a surface formed in compressive stresses will contain tensile residual stresses.

Illustration of the Bragg’s law which describes X-ray diffraction from crystal lattice planes.
March 7, 2018

Stresstech Bulletin 12: Measurement Methods of Residual Stresses

There are many methods to measure residual stresses. The methods are commonly grouped as non-destructive, semi-destructive and destructive or diffraction based, strain relaxation based and other methods. However, they all have the same common point: being indirect. There is no direct method available to measure stresses: they are calculated or derived from a measured quantity such as elastic strain or displacement.

distortion and residual stresses pdf cover
January 17, 2018

Stresstech Bulletin 9: Distortion and Residual Stresses

Distortion is the unexpected, uneven change in size or shape caused by dissimilarities in manufacturing and heat treatment processes. Distortion is affected by material properties, part geometry, the size of the component and the most importantly the residual stress state of the component.

importance of residual stresses cover
November 22, 2017

Stresstech Bulletin 7: The Importance of Residual Stresses

Independent of external loads, there are internal stresses inside structures and materials. These stresses are called residual stresses. Even though “stress” is an abstract term, the plural form “residual stresses” is often used. Residual stresses / Residual Stress terms were first mentioned in literature already in 1841. Since then, the importance of residual stress has become a well-known fact.

grinding residual stresses
November 13, 2017

Stresstech Bulletin 6: Grinding Residual Stresses

Grinding is a chip-forming process which requires high energy to remove material to specified dimensions. The high energy, in return, generates heat which is created by the interactions of the grinding wheel with the workpiece. The generated heat energy is absorbed by the workpiece which increases the temperature of the workpiece from the surface layer into the subsurface zones.