Experimental and numerical investigation of the fracture in steel welded joints

摘要

The work is devoted to the experimental and numerical investigation of fracture of the laser-welded specimen under quasi-static tension. In present study, two different steels stainless 316LN and P91 were welded with Laser Welding Process. The experimental study was carried out in Indira Gandhi Centre for Atomic Research (India). The evolution of the temperature field during each test was record by infrared camera CEDIP 420. Experimental results have shown quasi-wave character of the temperature evolution accompanying the specimen fracture process. During the experiments authors shown that accumulation of plastic strain irregular between joined materials, plastic flow in the P91 side overtakes plastic flow in the SS316LN side due to the various strain hardening rates of those materials. Numerical simulation of a tensile test was performed in the finite-element package Comsol Multiphysics under plane stress conditions. Simulation was carried out for two cases: small strain condition and large plastic strains, large plastic strains allow illustrate the necking effect of the specimen in the localization zone. The temperature evolution on the surface of a specimen has quantitative correspondences with the experimental results. Results of numerical simulation provided an explanation of the observed phenomena and let us to propose a model of strain localization.