Mechanical Properties and Microstructure of Hot Rolled High Al low Si Dual Phase Steel
A high-Al low-Si dual phase (DP) steel processed through thermo-mechanical processing practice involving combination of hot rolling and water quenching was studied in terms of structure-mechanical property relationship.The structure of the steel was strongly influenced by the start rolling temperature.At start rolling temperature of 1150℃ (steel 1),blocky-type martensite was obtained,but decreasing the start rolling temperature to 1000℃ (steel 2),long strip-type martensite formed along the rolling direction.This change in martensite morphology indicated that the dynamic recrystallization temperature of the experimental steel was greater than 1000℃ as Nb formed fine NbC carbides pinning the grain boundaries.Moreover,different start rolling temperature resulted in a difference in size of ferrite grain.The main factor that governed the mechanical properties was the hardness of martensite.Higher hardness of martensite led to higher strength but lower plasticity.The strain hardening of these two steels were studied.It showed that steel 2 had higher ability to strain hardening at small strain until the true strain reached 0.02.With increase in strain,the n value decreased rapidly.The slope of steel 2 was higher than steel 1 and a constant n value in steel 1 at large strain was obtained,which means that steel 1 had a sustainable strain hardening ability.The decrease in the hardness of martensite enhanced the strain hardening ability,while ferrite influenced the fracture characteristics.There was a high tendency to cleavage,when large number of ferrite grains with 100 orientation and hardness was high in the adjacent area between martensite and ferrite.
dual phase steel hot rolled microstructure fracture
ZHANG Jiecen DI Hongshuang
State Key Laboratory of Rolling and Automation, Northeastern University,Shenyang 110819, Liaoning, China
国际会议
成都
英文
504-507
2016-11-16（万方平台首次上网日期，不代表论文的发表时间）