| Low-alloy steel can be applied to armored steel because of low cost and simple production process.This paper studied the microstructure evolution and mechanical property of BR450 low-alloy steel by regulating the heat treatment process.This paper discuss the static/dynamic mechanics performance of tested steel by the static mechanics performance test and dynamic mechanics performance test(the Split Hopkinson Pressure Bars).The results of the paper are listed as follows:With the elevating of the tempering temperature,the impact toughness of tested steel would increase first and then decrease after a period of time.The strength and hardness of tested steel decreased gradually with the dislocation density in martensite reduced gradually in the process of tempering.The main function of tempering was relieving strees when tempering at 175℃~225℃.The internal stress was released with increasing tempering temperature and fine dispersed ε-carbide formed.The toughness was also improved to some extent.With the increase of tempering temperature,remaining austenite and ε-carbide transformed into cementite.Tempering at 425℃,large amount of cementite was found,which lead to the worst impact toughness and the one-step temper embrittlement.Tested the dynamic mechanical properties of test steel by using hopkinson pressure bar test,get the stress-strain relationships under different strain rate.The state of the test steel under impact load was described using Johnson-Cook constitutive model.The constitutive equation of the test steel was fitted.The bullet-proof performance of the test steel was simulated using explicit dynamic finite element simulation software ANSYS/LS-DYNA,providing a reference for the application of test steel.According to series heat treatment tests and numerical simulation results,the test steel tempering process was optimized.The test steel has good bullet-proof performance when quenching at 920℃and tempering at 225℃... |
