Simulation Investigation the Effect of Heating-Lines on Tensile Mechanical Properties of Sheet Metal after Laser Scanning

In this study, tensional mechanical properties of sheet metal with heating-lines after laser scanning are investigated based on the thermal-microstructure-mechanical model. The phase transformations, during laser scanning of sheet metal, are calculated by coupling the thermal history from finite element analysis with a phase transformation kinetic model. The flow stresses of material are obtained from the constitutive relationship of the phases based on the mixture strain hardening laws. The results show that the influence of the heating-lines number on tensional mechanical properties of material is obvious. The mechanical properties are related to the distribution of microstructure in heat affected zone after laser scanning.

Diffusion under a Stress in Metals and Interstitial Alloys

Elastic fields, generating by precipitates, cracks, dislocations and other defects of the structure, influence the diffusion processes. It leads to the alteration of the phase transformation kinetic, segregation formation and changes of the alloy properties. However, understanding the effects of strain on diffusion in solids is now limited. One of the chief aims of our approach is to obtain the general equations for the diffusion fluxes under strain that give the possibility of using these equations at low temperatures, as in this case, the strain influence on the diffusion fluxes is manifested in maximal degree. Recently some important generalization of our approach was done and equations for the vacancy fluxes in cubic metals were obtained. Now we have made the next step in the development of approach: general equations for the fluxes in interstitial alloys are obtained for different kinds of jumps in bcc and fcc structures. We are going to discuss the main features of the theory of diffusion under stress, to compare the equations for the fluxes and to present results of theory applications that are obtained with the help of computer simulations.

Investigation of Effect of Phase Transformations on Mechanical Behavior of AISI 1010 Steel in Laser Forming

In laser forming, phase transformations in the heat affected zone take place under steep cooling rates and temperature gradients, and have a significant affect on the laser forming process and final mechanical properties of products. In this work, phase transformations during laser forming of AISI 1010 steel are experimentally and numerically investigated and the transient volume fraction of each available phase is calculated by coupling the thermal history from finite element analysis with a phase transformation kinetic model. Consequently, the flow stresses of material are obtained from the constitutive relationship of the phases, and the laser forming process is modeled considering the effect of work hardening, recrystallization and phase transformation. A series of carefully controlled experiments are also conducted to validate the theoretically predicted results.