Effect of sheet-specimen geometry on plasticity and the deformation curve

Conclusions

• 1. In tensile tests on plane specimens of steel Kh18N10T, brass L-62, and molybdenum TsM-2A, the curves of the deformability (strengthening) are independent of the ratio of specimen width to its thickness, and the experimental points are found to fall satisfactorily within a single band of deformability.

• 2. The plasticity of all the tested metals and alloys diminishes with increasing ratio b₀/a ₀, down to a definite value, which is different for various metals, thereafter remaining constant.

  When the ratio b₀/a ₀ exceeds 20, the plasticity of all the investigated materials remains virtually unchanged. Therefore, one should recommend for tensile tests of sheet materials, that the specimens be manufactured with a width/thickness ratio of not less than 20.

• 3. For ratios b₀/a ₀ of 10 or more, the plasticity of steel and brass increases abruptly owing to the appearance of supplementary slip lines and another failure pattern.

• 4. The plasticity changes owing to a change in the stressed state (transverse tensile stresses appear).

• 5. With changes in the ratio b₀/a ₀, the stressed state depends on the necking radius and the strain pattern, the latter varying from a plane-stress state (in narrow specimens) to one of almost plane strain (in wide specimens).