r. barkhordari

This study investigates the anisotropic damage growth and martensitic phase transformation in AISI-316 austenitic stainless steel at room temperature. Initially, tensile and torsion tests were performed on samples at various displacements. Following these tests, the samples were analyzed using X-ray diffraction (XRD) to identify the present phases and determine the martensite volume fraction. The experimental data obtained were then used to develop a numerical model implemented in Abaqus software using the UMAT code. The simulation covers two main aspects: martensitic phase transformation and anisotropic damage growth, with the code capable of predicting both phenomena at room temperature. Damage mechanics is a relatively new tool in mechanical engineering, complementing the theories of plasticity and fracture mechanics. This study experimentally examined the process of damage growth and phase transformation in 316 stainless steel. The innovation of this model lies in its simultaneous consideration of anisotropic damage growth and austenite-to-martensite phase transformation at room temperature. The damage model used in this study is the Limiter model. Experimental tests, including tensile and torsion tests, were conducted to assess damage in different dimensions, involving both loading and unloading conditions. The model by Shin and colleagues was utilized to determine the phases present in the material. For greater accuracy in phase transformation testing, the samples were prepared using a water jet and then subjected to X-ray diffraction to measure the extent of martensite phase development. Finally, the numerical simulation was calibrated against experimental results for 316 stainless steel, ensuring the model's accuracy. Austenitic stainless steels transform into the martensite phase under strain, where the unstable austenite phase converts into stable martensite due to plastic deformation. This martensitic phase transformation hardens the austenitic steels. This study examines the anisotropic damage growth resulting from plastic strain and the martensitic phase transformation in austenitic stainless steels, specifically AISI-316, at room temperature. Initially, tensile and torsion tests are conducted on the samples at various displacements. Subsequently, these samples undergo X-ray diffraction tests to determine the existing phases and the martensite volume fraction in the samples. Using the obtained results, an empirical model is created from numerical tests using the UMAT code in Abaqus software. This simulation includes both the martensitic phase transformation and anisotropic damage growth. The code can predict any phenomenon under environmental conditions. Finally, the effectiveness of the proposed model is compared and analyzed against experimental results for AISI-316 steel.

In this research, the evolution of damage and martensitic transformation of AISI 304, 316 and 321 stainless steels have been studied experimentally and numerically at room temperature. At first stage, the standard tensile tests have been performed and in the second stage the XRD has been tested and the available phases and the volume fraction of martensite have been obtained. The tensile tests have been performed for a variety of loading-unloading elongation. Damage is obtained using this loading-unloading slop. The graph of force-deformation has been achieved. The samples were cut by water jet machine and the X-ray diffraction tests have been performed on the stretched samples to obtain the volume fraction of martensite. Numerical simulations have been performed by the implementing the UMAT code in ABAQUS. In the simulations, the properties achieved from experimental tests are employed. The numerical simulations have two separated sections: damage-plastic and martensitic phase transformation. In this research, these two phenomena are considered simultaneously. This model can explain both phenomena at ambient temperature. The verifications have been compared simulation results with experimental data.