Retained Austenite Destabilization during Tempering of Low-Temperature Bainite

Ruiz-Jimenez, Victor; Kuntz, M.; Sourmail, Thomas; Caballero, Francisca G.; Jiménez, José A.; García‐Mateo, C.

doi:10.3390/app10248901

Cited by 31 publications

(16 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…III). This con rm degradation of the microstructure during annealing at higher temperature -carbides precipitation and retained austenite transformation [14,17] . On the basis of dilatometric and mechanical tests the temperature of low temperature glow discharge nitriding was selected at 420°C.…”

Section: Simulation Of Nitriding Processes In Dilatometric Testsmentioning

confidence: 57%

Glow discharge nitriding of nanobainitic X37CrMoV5-1 steel

Skołek

Chmielarz

Marciniak

et al. 2023

Preprint

View full text Add to dashboard Cite

One of the methods of improving mechanical properties of steels is nanostructuring via austempering, which leads to formation of a nanobainitic microstructure - a fine carbide-free bainitic ferrite plates with retained austenite. Due to high density of grain and interphase boundaries, this microstructure provides high tensile strength. Moreover, high amount of retained austenite guarantees high ductility and fracture toughness. However, retained austenite may also decrease hardness and wear resistance. Thus, to improve the properties of the surface an additional process is necessary. There are several methods of surface engineering which allow to produce hard diffusive layer, however most them are usually carried out at a temperature, in which nanobainite decomposes and loses its high properties. The purpose of the present work was to produce hard and wear-resistant nitrided diffusion layers on nanobainitic X37CrMoV5-1 steel surface during glow discharge nitriding, while keeping microstructure in core of the sample almost intact. Two temperatures of a nitriding were chosen. Obtained results were compared to the layers produced at quenched and tempered substrate to determine the influence of the microstructure of the substrate on the kinetics of the layer’s growth. The microstucture of the layers were described and their properties such as microhardness and wear resistance were investigated.

show abstract

Section: Simulation Of Nitriding Processes In Dilatometric Testsmentioning

confidence: 57%

Glow discharge nitriding of nanobainitic X37CrMoV5-1 steel

Skołek

Chmielarz

Marciniak

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Thus, the de-composition mechanisms should be comparable to the tempering processes. Retained austenite during tempering decomposes into a mixture of cementite and ferrite (γ R → α + θ ) [21]. There Austenite decomposition products may also be pearlite [22], martensite (induced transformation of retained austenite [23]), and bainite [24].…”

Section: Resultsmentioning

confidence: 99%

Decomposition mechanisms of continuously cooled bainitic rail in the critical heat-affected zone of a flash-butt welded joints

Królicka

Żak

Kuziak

et al. 2021

Materials Science-Poland

View full text Add to dashboard Cite

The joining process of bainitic rails is significant in terms of their industrialization in high-speed and heavy-loaded railways. This paper demonstrates the microstructure changes in the critical zone of the welded joint, which is responsible for the greatest deterioration in mechanical properties. Extensive progress in the decomposition of the retained austenite and bainitic ferrite occurs in the low-temperature heat-affected zone (LTHAZ) of the flash-butt welded joint of low-carbon bainitic rail. The decomposition products of the retained austenite were mainly a mixture of cementite and ferrite. The cementite was mainly precipitated at the boundary of the bainitic ferrite laths, which indicates lower thermal stability of the filmy austenite. Moreover, it was found that a part of the refined blocky retained austenite was decomposed into the ferrite and nanometric cementite, while another remained in the structure. The decomposition mechanisms are rather heterogeneous with varying degrees of decomposition. A relatively high proportion of dislocations and stress fields prove the occurrence of residual stresses formed during the welding process.

show abstract

“…Although Mn is a stabilizer of austenite, it was proposed to reduce its content (0.5 wt.%) and increase the content of Cr (1.5 wt.%) to accelerate bainite transformation and achieve sufficient hardenability. It was stated that V (0.2 wt.%) has a beneficial effect on retarding the decomposition process during tempering [28,29]. Another aspect is also controlling the grain size of the prior austenite, which is significant in terms of steel's susceptibility to grain coarsening.…”

Section: Design Process Of Experimental Steelmentioning

confidence: 99%

“…However, it was observed that the hardness at 550 • C was comparable to the state before tempering. This may be explained by the strengthening effect of fine-dispersed carbide precipitations (related to alloying elements such as Mo and V-secondary hardening), similar to [29,52].…”

Section: Tempering Process-thermal Stability Evaluationmentioning

confidence: 99%

Controlling the Thermal Stability of a Bainitic Structure by Alloy Design and Isothermal Heat Treatment

et al. 2023

Self Cite

View full text Add to dashboard Cite

The aim of this work was to develop a novel bainitic steel that will be specifically dedicated to achieving a high degree of refinement (nano- or submicron scale) along with increased thermal stability of the structure at elevated temperatures. The material was characterized by improved in-use properties, expressed as the thermal stability of the structure, compared to nanocrystalline bainitic steels with a limited fraction of carbide precipitations. Assumed criteria for the expected low martensite start temperature, bainitic hardenability level, and thermal stability are specified. The steel design process and complete characteristics of the novel steel including continuous cooling transformation and time–temperature–transformation diagrams based on dilatometry are presented. Moreover, the influence of bainite transformation temperature on the degree of structure refinement and dimensions of austenite blocks was also determined. It was assessed whether, in medium-carbon steels, it is possible to achieve a nanoscale bainitic structure. Finally, the effectiveness of the applied strategy for enhancing thermal stability at elevated temperatures was analyzed.

show abstract

Retained Austenite Destabilization during Tempering of Low-Temperature Bainite

Cited by 31 publications

References 52 publications

Glow discharge nitriding of nanobainitic X37CrMoV5-1 steel

Glow discharge nitriding of nanobainitic X37CrMoV5-1 steel

Decomposition mechanisms of continuously cooled bainitic rail in the critical heat-affected zone of a flash-butt welded joints

Controlling the Thermal Stability of a Bainitic Structure by Alloy Design and Isothermal Heat Treatment

Contact Info

Product

Resources

About