the unique properties of air-cooled bainitic steels have been described. a series of mn containing air-cooled bainitic steels invented by authors is presented in this paper: including low carbon granular bainitic steels, low carbon grain-boundary allotriomorphic ferrite/granular bainite duplex steels, medium and medium high carbon bainite/martensite duplex steel, and low carbon carbide free bai...

The effect of multi-step austempering treatments on the microstructure and mechanical properties a novel medium carbon high silicon carbide-free bainitic steel was studied. Five different isothermal treatment processes were selected, including single-step above martensite start temperature (at 350 °C 370 °C, respectively), three kinds two-step routes (370 + 300 250 °C). In comparison with adopt...

This paper discusses the use of laser-ultrasonics to monitor the metallurgical transformations of advanced high-strength steels. In this technique, acoustic waves are generated and detected in the material by use of lasers. The ultrasonic velocity can sense the austenite formation/decomposition in real time. Unlike dilatometric measurements the ultrasonic velocity measurements show little influ...

Bainite has been obtained by heat treatment at temperatures as low as 125°C in a high carbon, high silicon steel. This has had the effect of greatly re® ning the microstructure, which is found to have a strength in excess of 2.5 GPa together with an ability to ̄ ow plastically before fracture. Such properties have never before been achieved with bainite. In this paper metallographic details are ...

Controlling the grain size of steels is an effective way for tailoring their mechanical properties, such as yield strength, impact toughness, and ductility. In this study, a new industrial thermomechanical treatment was applied to low-alloyed TRIP-assisted bainitic steel 13MnSiCr7 achieve substantial microstructural refinement. average micro-bainitic decreased from ∼25 μm ∼5 μm. Fatigue tests w...

The microstructural evolution of and simultaneous dimensional changes in high-carbon SAE 52100 bearing steel were monitored continuously during austempering for 120 min at selected temperatures the range 210 °C-270 °C, also its subsequent tempering to 340 °C an additional min, via high-energy X-ray diffraction real time in-situ dilatometry. austenite-to-bainitic ferrite transformation induces l...

The effect of tempering temperature, within the range of 400 to 700°C, on the microstructure and hardness of two super-bainitic steels, one as the control parent sample and the other with added Co & Al was investigated. Post-tempering examinations of the super-bainitic samples showed that low temperature tempering cycles (400–500°C) resulted in carbides formation, and some increases in the hard...