The Microstructure Evolution during Partitioning Process in a One-step QP Steel

摘要

Quenching and partitioning (Q&P) process is a heat treatment of martensite which is different to customary quenching and tempering.In this paper,a Q&P process which is partially austenized followed by a one-step quenching and partitioning procedure was applied to a low-carbon Mn-Si-Al TRIP-aided steel.The purpose of this experiment is to investigate the phase transformations during partially austenized with different annealing temperatures and partitioning times.The work was carried out in a dilatometer.The microstructure was characterized by means of electron probe microanalysis (EPMA).The results shows that the microstructures formed are ferrite,martensite,bainite and retained austenite.The results obtained by dilatometry reveals that the volume fraction of bainite increases with the prolongation of partitioning time and the temperature interval of bainite was not only above and also below the Ms temperature.The microstructures developed into temper morphology along with the prolongation of partitioning time,and the carbide was suppressed due to the effect of Al and Si elements.