The development of ultrafine bainitic structure in AISI 431 stainless steel was the goal of this study. For this purpose, the AISI 431 specimens were austenitized at 1100 °C for 60 min followed by low-temperature austempering treatment at different temperatures and times. Austempered samples were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (X...

This study reports the welded joint of a novel 590 MPa V-N microalloyed wheel steel on microstructure and mechanical properties after flash butt welding. The welding parameters were current 48°/582.0 A, upsetting 44°/516.6 workpiece clearance 1.5 mm. evolution in occurred as follows: seam (ferrite side plate + acicular ferrite +martensite)→coarse-grained zone (acicular granular bainite)→fine-gr...

Abstract The deployment of Press Hardened Steels (PHSs) in the Body-In-White structures that took place during two last decades is at origin a breakthrough weight saving on vehicles while guaranteeing safety requirements automotive industry. production parts with complex shapes and high strength between 1500-2000MPa was made possible by taking advantage hot rheology austenite combined fast cool...

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...

Nanostructured bainite was obtained in high-carbon Si-Al-rich steel by low-temperature (220-260 °C) isothermal transformation after austenitisation at different temperatures (900 °C, 1000 °C, and 1150 °C). Improved strength-ductility-toughness balance was achieved in the nanostructured bainitic steel austenitised at low temperatures (900 °C and 1000 °C). Increasing the austenitising temperature...

Incomplete bainitic transformation during austempering treatment is mainly caused by the supersatu-ration of austenite with carbon. Such supersaturated becomes more stable and further stabi-lization led silicon alloying. Stable does not transform remains in structure as so-called residual austenite. Therefore, carbides, which are desirable a conventional struc-ture, cannot be formed carbide fre...

This study aims to examine the correlation between microstructures and mechanical properties of two high-strength API X70 linepipe steels with different specimen directions Moaddition. The microstructure Mo-added steel has an irregularly shaped AF, GB matrix pearlite because relatively large deformation in non-recrystallization temperature region, while that Mo-free shows a PF bainitic microstr...

Shielded metal arc welding and thermal simulation experiment were carried out for constructional steel containing 0% V 0.10% V, the microstructure, precipitation feature, microhardness HV0.2, −20 °C impact value in heat affected zone (HAZ) investigated. The results showed that coarse-grained (CGHAZ), N completely dissolved matrix of to promote growth prior austenite grains, meanwhile fraction h...

The influence of microstructure on tensile properties and stretch-flangeability TRIP steels with strengths higher than 1.2 GPa has been investigated under various Quenching Partitioning (Q&P) conditions. As lowering the quenching stop temperature, QT, below Ms temperature in range 340°C to 280°C, volume fractions tempered martensite retained austenite increased bainite fresh decreased final mic...