Evaluation of local strength of welding joint by using double holes micro shear test

A new approach, double holes micro shear test, is presented for determining the localplastic deformation properties in welded joints. A device for measuring the local mechanical properties of materials is developed and the micro shear test of the welded joint is carried out.The response between applied load and indentor displacement is recoroled. shear stress-strain curve. the finite element model of double hole micro-shear test is established. The finite element computation were carried out for various combination of yield stress and work hardening exponent. The equations were constructed to material strength properties and load-displacement curves from double holes micro-shear tests. The accuracy of this equations method is validated by tensile test. The results show that the material strength properties can be obtained directly from the experimental curves with double hole micro-shear test. The local distortion properties in X70 pipeline steel welded joints were evaluated by double holes micro shear test.