Residual stress tensile

Contain tensile residual stresses which are usually as large as the yield stress. Weld liable to fatigue even when applied stress cycle is wholly compressive. Reduce residual stresses by stress relieving, hammering or shot peening. 

A metal s resistance to fatigue is markedly reduced in a corrosive environment. Many welded structures are subjected to fluctuating stresses which, with the superimposed tensile residual stress of the joint, can be dangerous. In addition to this a welded joint is a discontinuity in an engineering structure containing many possible sites of stress concentration, e.g. toe or root of the joint, weld ripple. 

Undesirable influence of tensile residual stresses on a laminate... 

Stress-relief at low appropriate temperatures is commonly used to lower susceptibility. Tensile residual stresses from welding can be particularly dangerous and a low-temperature thermal stress-relief treatment is recommended for welded assemblies.157... 

Fig. 7 Cracks in a high strength steel relief valve spring. The cracks have been revealed using a dye that penetrates into the crack then seeps back out into a porous white coating. The cracks were caused by hydrogen embrittlement of the excessively hard steel, coupled with tensile residual stresses and the storage environment on a chemical plant (with an occasional trace of H2S). (View this art in color at www.dekker.com.)...

There is some indication of a marginal increase in the weight fraction of tetragonal zirconia (Table 1) with depth. In the alumina-zirconia (90 10 by weight) control sample, the content of the t-phase is approximately 5 wt%. On the surface of the FGM sample, where AT is approximately 45 wt%, the weight fraction of t-phase is 1.0% and this value increases up to 2.4% at a depth of 1.2 mm. It is suggested that the presence of AT has induced tensile residual stresses which are responsible for enhancing the t->m phase transformation. 

Measured stresses (figs, la, lb) showed the effectiveness of the thermoelastoplastic coupling, inducing lower tensile residual stresses with respect to the thermoelastic case. The comparison with analytic and... 

Abrasive processes are generally the final process operation in a process chain and determine significantly the functional surface properties of the machined workpiece. Therefore, the properties of the surface layer generated by abrasive processes directly affect the functional properties of the workpiece such as fatigue strength, wear behavior, and chemical resistance (Jawahir et al. 2011). Tensile residual stresses impair mechanical strength properties of workpiece, whereas compressive tensile stresses have a beneficial effect. 

Balart MJ, Bouzina A, Edwards L, Fitzpatrick ME (2004) The onset of tensile residual stresses in grinding of hardened steels. Mater Sci Eng... 

During machining, the material subsurface is heated temporarily to high temperatures. By this the surface-near layers expand as a result of thermal compressive stress. The surface-near layers deform plastically in a state of reduced yield strength. After cooling down to room temperature, tensile residual stresses result. As in machining both mechanical and thermal influences act concurrently, they interfere with each other strongly nonlinear. A simple superposition is not... 

Internal oxidation of SiC/RBSN is severe between 800 to 1100°C, and the depth of the oxidation damage zone is directly related to the pore size the smaller the pore size, the lower is the oxidation induced damage. In addition, internal oxidation is also found to generate tensile residual stresses which affect strength properties of SiC/RBSN. 

Raman spectroscopy of SiC particles within the scratch groove indicated development of tensile residual stress which increased with increasing scratch load. 

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