Metastable ω phase is common in body-centred cubic (bcc) metals and alloys, including high-alloying steels. Recent theoretical calculations also suggest that the ω structure may act as an intermediate phase for face-centred cubic (fcc)-to-bcc transformation. Thus far, the role of the ω phase played in fcc-bcc martensitic transformation in carbon steels has not been reported. In previous investi...

the quenching and partitioning (q&p;) process is a new heat treatment cycle to produce the third generation of advanced high strength steels based on diffusion of carbon from martensite to retained austenite phase. the application of this process for various steels leads to a remarkable combination of mechanical properties including high strength and good ductility. using this process in automo...

Carbonitriding of four types of steels, namely, low carbon steel (LCS), medium carbon steel (MCS), low alloy steel (LAS) and high alloy steel (HAS) was achieved using cyanide salt bath heat treatment process. The steels, after preheating, were heated in a diesel fired salt bath heat treatment furnace and then quickly quenched in different media including air, oil and brine. The heat treatment p...

Cementite dissolution in hypereutectoid steels containing Cr is analyzed using dilatometry combined with the consideration of the carbon content in the austenite. The results suggest that the austenite transformed from the mixture of ferrite and cementite can be approximated to have a carbon content corresponding to equilibrium with ferrite. The overall dissolution behavior of cementite is desc...

Many steels contain substitutional solutes which have a strong affinity for carbon or nitrogen. Such steels can be hardened by heat treatment which induces the precipitation of fine alloy carbides. Examples of such carbides include MX, 2 73 , 6 and 236 , where M stands for a mixture of iron and substitutional solute atoms and X stands for interstitial solute atoms. In practice, the heat treatme...

In this work, three low-carbon bainitic steels, with different Mo contents, were designed to investigate the effects of Mo addition on microstructure and mechanical properties. Two-step cooling, i.e., initial accelerated cooling and subsequent slow cooling, was used to obtain the desired bainite microstructure. The results show that the product of strength and elongation first increases and the...

The carbon contents in carburized steels were investigated by electron probe microanalysis (EPMA) for a range of carbon levels in the solid solution less than 1 wt%. This article describes the difficulties encountered with the classic analytical procedure using the k ratio of X-ray intensities and the phi(rhoz) model. Here, a suitable calibration curve method is presented with emphasis on the m...

Low carbon steels are widely used for structural applications because of its ease in fabrication and the moderate strength it posses. However, its pure corrosion resistance at normal atmosphere is a matter of serious concern.

In recent years, there has been a growing interest in steels of multi-phase structures, composed of a ferritic matrix, in which islets occur, that contain bainite-B, martensite-M and the untransformed austenite-A 1-9 . The multi-phase structure of steel with untransformed austenite promotes the increase of plasticity induced by the phase transformation – the TRIP effect 3-4, 6-8 . In steels con...

The possibility to obtain multiphase steels with considerable fractions of retained austenite, which is of key interest for the occurrence of the TRIP effect, is investigated in steels with low amounts of Si and Al. Special emphasis is dedicated to the microstructural observation of this phase, since its volume fraction, distribution and stability, related to the carbon content, will determine ...