Quantitative Analysis on Carbide Precipitation in V-Ti Microalloyed TRIP Steel Containing Aluminum

Abstract

Abstract. Introducing fine precipitates is an important way to enhance the properties of transformation-induced plasticity (TRIP) steels. In present work, two V-Ti microalloyed TRIP steels containing aluminum with different content were compared. The average size, size distribution and numbers of vanadium-titanium carbides in samples cold rolled, quenched after being held at 800°C and quenched after intercritical annealing at 800°C and being held at bainitic isothermal transformation temperature of 400°C were investigated by using the technique of carbon extraction replica, twin jet chemical polishing thinning and transmission electron microscopy. The carbides were identified to be (Ti,V)C precipitates in steel A and VC in steel B respectively, precipitated mainly from ferrites grains. The average equivalent radius was 3~6nm. Comparison of the experimental results in A and B steel revealed low carbon diffusion rate caused by aluminum inhibited the coarsening of vanadium-titanium carbides. The experimental results also showed that VC carbides dissolution occurred during the intercritical annealing at 800°C.

Carbide precipitation during tempering of hybrid steel 60

“…Spheroidized carbides can substantially avoid becoming the starting point of cracks, thereby improving the fatigue strength and fracture toughness of the material. V precipitates as carbides between 500 and 700 °C in bainite and martensite and dissolves at 800 °C [30][31][32]. The VC diffraction peak in figure 7 To investigate the precipitation behavior of carbides, the relationship between carbide precipitation and interface binding strength was analyzed using transmission electron microscopy.…”