Phase transitions in CuAlMn alloys containing up to 12 at% Mn and 27 at% A1 continuously heated up to 5500C were studied using differential scanning calorimetry and transmission electron microscopy. Alloys containing less than 4.8 at% Mn exhibit an exothermal heat effect in the range 280 380°C due to y2 precipitation. The additional endothermal peak above 5000C is caused by DO3 disordering. All...

With careful design, mixed microstructures consisting of fine plates of upper bainitic ferrite separated by thin films of stable retained austenite have exhibited impressive combinations of strength and toughness in highsilicon bainitic steels. The silicon suppresses the precipitation of brittle cementite leading to an improvement in toughness. The essential principles governing the optimisatio...

The successive ferrite (α) + pearlite (P) transformations from austenite (γ) have been modeled to predict the intervention of bainite in as-forged medium-carbon manganese steels. The kinetics of the diffusional transformations were calculated based on the classical nucleation-growth theory coupled with the CALPHAD multi-component thermodynamics. The description of growth rate of proeutectoid-α ...

The design and development of new multiphase microstructures for specific technological applications require not only a characterization of the final microstructure, but also a detailed knowledge at the level of individual grains of the phase transformations taking place during the material processing. The availability of intense high-energy X-ray beams (50 to 300 keV) at a number of synchrotro...

In this paper, a 0.2 C–1.6 Mn–1.5 Si wt. % TRIP-aided cold-rolled steel sheet was fabricated and the optimal heat treatment conditions (Intercritical Annealing “IA” and Bainitic Isothermal Transformation “BIT”) were investigated to maximize the volume fraction and stability of the retained austenite. The effects of temperature on IA (770, 790 and 810 ºC) and BIT (330, 350 and 370 <su...

In this paper, a new low-carbon alloy gear steel is designed via Si/Al alloying. The carburizing and austempering, at temperature slightly higher than the martensitic transformation point (Ms) of surface much lower Ms core, for different times, were carried out on newly steel. After heat treatment, series microstructures (superfine bainitic ferrite + retained austenite, superfine martensite aus...

In the current research, a complex microstructure and crystallographic data were developed through quenching partitioning (Q&P) process to improve tensile properties of commercial pearlitic carbon-silicon steel. Two-stage Q&P process, including full austenitization, at 220 °C, followed by two different temperatures, was applied as-received specimen generate composed tempered martensite, bainite...

Abstract The microstructure of a low alloy medium carbon bainitic steel, austempered in the temperature range 275 °C to 450 has been investigated by detailed electron backscatter diffraction and variant pairing analysis. It is observed that tendency two distinct changes with varying temperature. At V1-V6 most frequent, whereas V1-V2 frequent at intermediate highest temperature, V1-V4 dominates....

A PM approach is investigated in the context of extremely fine low temperature bainitic steels with a reasonable combination of ultimate tensile strength and uniform elongation. The strategy consists of three steps. First, ball milling is used for mechanical alloying and to create a large density of interfaces prior to sintering. In the second step, spark plasma sintering is used as a rapid con...