The recently developed nanobainitic steels show high strength as well as high ductility. Although this combination seems to be promising for fatigue design, fatigue properties of nanostructured bainitic steels are often surprisingly low. To improve the fatigue behavior, an understanding of the correlation between the nanobainitic microstructure and the fatigue limit is fundamental. Therefore, o...

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 ...

Knowledge of carbon content in retained austenite (RA) with different neighbouring phases is essential to understand the chemical stability of RA, which is useful for microstructure tuning of transformation-induced plasticity (TRIP) steels. The present study investigates different morphologies and chemical compositions of RA by correlating electron backscattering diffraction, transmission elect...

The mechanism of the bainite transformation in carbon containing steels was discussed after presenting our recent experimental results; (1) the bainite transformation has its own C-curve, (2) incomplete phenomenon is a general feature of the bainite transformation, (3) bainitic fenite grows to a limited size, and (4) bainitic ferrite is highly supersaturated with respect to carbon. It was exami...

Specimens with different microstructures (bainite, as-quenched martensite, and tempered martensite) were fabricated using a Fe-0.4C-1.5Si-2Mn steel sheet, the pitting corrosion resistances of these compared. Retained austenite was barely detected in X-ray diffraction analysis. The Vickers hardness values ordered as (high) martensite > ≈ bainite 325°C-austempered specimen 425°C-austempered (low)...

The microstructure and microhardness of X70 pipeline steel were investigated after conducting different processing routes. was characterized using optical electron microscopy. Scanning microscopy equipped with backscattered diffraction (EBSD) transmission techniques applied for investigation thermal treatment conditions. Mechanical properties by a tester. results show that the mainly consists g...

SUS440 is a high-carbon stainless steel, and its martensite matrix has high heat resistance, high corrosion resistance, and high pressure resistance. It has been widely used in mechanical parts and critical materials. However, the SUS440 martempered matrix has reliability problems in thin plate applications and thus research uses different austempering heat treatments (tempering temperature: 20...

The microstructure and properties of a 5 wt.% Cr cold work tool steel were studied after austenitisation at 1020°C, 1050°C or 1075°C followed by single, double and triple tempering treatments at 525°C. The microstructures were investigated with scanning electron microscopy and X-ray diffraction and phase transformations were studied by dilatometry. Furthermore, hardness and Charpy un-notched an...

The strength of mixed microstructures of bainite and martensite can peak at an intermediate volume fraction of martensite has been published by recently experimental studies. A quantitative interpretation of these observations is achieved by modelling the mechanical properties of mixed microstructures of bainite and martensite. The peak in the curve of the strength as a function of the volume f...