Elongation without necking

Figure 3 shows the true stress strain curves for the consolidated microcrystalline powder. Both tensile and compression results show that sample 2B gives the best UTS and ductility. In tension, the 2B sample shows nearly ideal elasto-plastic response without necking until about 17 percent elongation. The... 

The effect of elevated irradiation temperatures is to reduce the yield stress increase, but the tensile strength increase may be greater under the higher temperature conditions. The uniform elongation is usually greater for elevated temperatures of irradiation. In some cases the reduction of area is drastically reduced by elevated temperature irradiations, and fracture has occurred without necking. Thus it is not clear whether elevated irradiation temperatures are always beneficial. 

Fig. 1 4.7 Superplastic tensile elongation, (a) 5 mm (0.2 in.) thick tensile sample, (b) Limited tensile elongation and severe necking without friction stir processing (FSP). (c) 800% superplastic elongation in 5 mm thick FSP 7075 Al...

Figure 2.33. Normally, tensile failure in hardened steel is a sudden, brittle fracture without previous plastic deformation (left). Typically, tensile failure in mild steel is a ductile fracture with considerable elongation taking place prior to fracture. Around the place of fracture a severe necking and reduction of cross-section is seen (right). The materials samples shown are made of amorphous metal.

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