Microstructures and Properties of Auto-Tempering Ultra-High Strength Automotive Steel under Different Thermal-Processing Conditions

Automotive steels with ultra-high strength and low alloy content under different heating cooling processes were investigated. It was shown that those exhibited a great influence on the performance of investigated due to auto-tempering effects. Compared water quenching, there approximately 70% increase in elongation air cooling, which martensite well-tempered. Although steel microstructure composed ferrite, well-tempered less-tempered could exceed 15%, hole expansion ratio still lower because undesirable hardness distribution between hard phases soft phases. followed from calculation results based SEM, TEM XRD analyses, for strengthening mechanism dominated by solid solution determined martensite. Experiments analyses aimed explore plasticity mechanisms special process flash heating.