Research On The Quenching- Partitioning(Q&P)steel Microstructure And Properties

Quenching partitioning(Q&P) steel is martensite steel to get more residual austenite through the distribution process. It belongs to the third generation of automotive steel, high strength and high toughness. In this paper, the quenching partitioning(Q&P) steel were systematically studied, was consistent with the tensile strength is 800 ~ 1500 Mpa, elongation of steel for the third generation car from 15%to 40%. The experiment based on the experimental steel after processing by microstructure observation and mechanical properties test, comparison and analysis of the quenching and partitioning process on the performance of the test steel at different temperature and different distribution with time. The main contents and conclusions are as follows:The main microstructure of steel is ferrite and pearlite, tensile strength 1085 Mpa,elongation is 14.75%. After the partition after the treatment, the mechanical properties have been greatly improved. The distribution temperature of 400 degrees, with time as the tensile strength of 30 s is 1336 Mpa, the elongation is 18.4%; the distribution in time for the tensile strength of 120 s is 1303 Mpa, the elongation is 20.6%; the distribution in time for the tensile strength of 300 s is 1295 Mpa, the elongation is20.15%. In the time of 450 degrees, with time as the tensile strength of 30 s is1468Mpa, the elongation is 20.95%, get the best mechanical properties; partition time for tensile strength of 120 s is 1260 Mpa, the elongation is 19.65%; the distribution in time for the tensile strength of 300 s is 1183 Mpa, elongation is 19.5%. After quenching and partitioning process after the microstructure is martensite and residual austenite, the volume fraction of retained austenite. The maximum is 14.2%.As the minimum is 8.23%.The microstructure of grain size, residual austenite content and its organizations in the form is the key material to obtain high strength and high plasticity. The fine grains and a large number of stable residual austenite can make the material for high strength and high plasticity...