Numerical and Experimental Investigation of Microstructure Evolution and Mechanical Behavior of Steel in Laser Forming

In laser forming, phase transformation and grain structural evolution in the heat affected zone (HAZ) take place under steep cooling rates and temperature gradients, and have a significant effect on the laser forming process and final mechanical properties of products. In this work, microstructure evolution during laser forming of AISI 1010 steel is experimentally and numerically investigated and the transient constitutive property of phases and grain size are calculated by coupling the thermal history from finite element analysis with a phase transformation kinetic model. Phase volume fraction and grain distribution are predicted. Consequently, the flow stress of material is 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.