Investigation On Hot Stamping Process Of High Strength Boron Steel

High-strength steel is widely used in Automobile lightening,which has excellent mechanical properties to reduce weight,keep high energy absorption capability and crash safety for auto parts.But High-strength steel is a difficult-to-deformation material mostly processed by hot stamping rather than cold stamping due to difficulties.This paper studies hot stamping of ‘W’ shape using 22 MnB5 high-strength steel and its modified type 97# Q-P steel,the research contents as follow:(1)Temperature,stress and strain field of 22 MnB5 high-strength steel was studied with initial temperature of 850℃ and holding pressure for 20 s by simufact.(2)Considering construct features of W shape workpiece and principles of hot stamping,a W-shaped mold was designed after selecting some important parameters.Some experiments were added to study the formation,structure,and mechanical properties under this condition(temperature of 850℃ and holding pressure for 20s).The results show that the workpiece has a good formation with initial temperature of 850℃ and holding pressure for 20 s.(3)The effect of water velocity on the temperature of workpieces and molds was analyzed using FLUENT software in the mold cooling system.The distribution of temperature,stress and strain field and extrusion pressure had been studied under different process parameters.The results show,water velocity reaches 1m/s has a better cooling effect.(4)Hot stamping of 97# steel was investigated with W-shaped mold,the effect of austenitizing temperature,austenitizing time,hold time and mold temperature on workpiece structure and mechanical property.The results show that,the workpiece’s final state is lath martensite without oxide coating on the surface.It has a good formation when austenitizing temperature is 900℃,austenitizing time is above 2 min,holding time is more than 30 s.(5)The workpiece was processed with low temperature tempering after hot stamping.The effect of tempering time and tempering temperature on its structure and mechanical property.The results show that,the appropriate tempering time is 5min~40min,and the appropriate tempering temperature is 200℃.