Continuous cooling deformation testing of steels

In this study, an energy-efficient processing route involving hot rolling and on-line heat treatment was proposed, which was applied to Al-containing hot-rolled TRIP steel. The experiments were carried out involving hot rolling and on-line heat treatment, where the samples were subjected to different processing routes. The results showed that the cooling temperature determined the microstructural type of experimental steels, while the cooling pattern determined the decomposition state of retained austenite. The introduction of polygonal ferrite in martensitic matrix, and decomposition of retained austenite in ferritic and bainitic matrix were harmful to impact toughness. The fracture mode in ferritic matrix through air cooling was ductile fracture containing dimples and the fracture morphology reflected the best impact toughness of 134 J in selected steels.

Section: Methodsmentioning

confidence: 99%

Characterisation on impact-toughness in Al-bearing hot-rolled TRIP steel produced through dynamic-partitioning

Wang

Kang

et al. 2021

“…The billets were reheated to 1200°C for 2 h in box type resistance furnace and hot rolled to 4 mm thick plates using 450 mm diameter hot rolling mill. The plates were hot rolled in the recrystallisation (HR1) and non-recrystallisation (HR2) regions, to conduct controlled rolling processing with two stages [11,12]. The rolling temperature in recrystallisation region was from 1120°C to 1080°C, while the rolling temperature in non-recrystallisation region was from 980°C to 940°C.…”

Section: Methodsmentioning

confidence: 99%

Characterisation on Al-bearing hot-rolled TRIP steel produced through isothermal bainite transformation

Wang

Kang

et al. 2020

In this study, an energy-efficient processing route involving hot rolling and on-line heat treatment was proposed, which is applied to Nb-alloyed and Al-containing hot-rolled TRIP steel. The experiments were carried out involving hot rolling and on-line heat treatment, where the samples were subjected to different bainite hold times. The results shows that during isothermal bainite transformation, film-like and blocky retained austenite were present in microstructures at bainite hold times of 10 and 20 min. The sample subjected to bainite hold time of 20 min exhibited excellent mechanical properties, with tensile strength of 839 MPa, total elongation of 38% and product of strength and elongation of 31.9 GPa%. The instantaneous work hardening exponent increased gradually with true strain at bainite hold time of 20 min.

“…no-recrystallisation temperature, austenite to ferrite transformation temperature and austenite to pearlite transformation temperature) of the steel, which was determined through continuous cooling compression test (CCC) method. 20 Microstructures were studied by using optical and scanning electron microscopy. The specimens were electrolytically polished and then were prepared using a particular tint etching method, adopted from LePera's technique.…”

Section: Methodsmentioning

confidence: 99%

Effect of prior austenite characteristics on mechanical properties of thermomechanically processed multiphase TRIP assisted steels

Hosseini¹,

Zarei-Hanzaki²,

Essadiqi³

et al. 2008

Self Cite

To develop any multiphase transformation induced plasticity (TRIP) assisted steel through thermomechanical processing routes, the effects of materials and process variables are to be thoroughly identified. Accordingly, the present work was programmed to study the influence of the state of prior austenite on the subsequent transformations and the related final phase combinations. In this framework, using a low carbon TRIP assisted multiphase steel, the compression specimens were subjected to different thermomechanical processing schedules to generate different prior austenite characteristics. The results indicated that the characteristics of martensite/austenite (M/A) microcomponent in the final microstructure were dictated by the state of prior austenite. In fact, increasing prior austenite grain size led to large decrease in the amount of M/A phase and this, in turn, resulted to higher strength without sacrificing the ductility. It was also found that static recrystallisation of austenite brings about more percentage of M/A phase compared with dynamic recrystallisation.