Critical isothermal temperature and optimum mechanical behaviour of high Si-containing bainitic steels

Misra, Anuradha; Sharma, S.; Sangal, S.; Upadhyaya, Anish; Mondal, K.

doi:10.1016/j.msea.2012.08.083

Cited by 26 publications

(7 citation statements)

References 23 publications

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“…The amount of RA was quantitatively obtained by comparing the integrated intensities of the (200) γ , (220) γ , (311) γ , and (200) α , (211) α peaks. [13][14][15] The formula is [15] f γ =…”

Section: Methodsmentioning

confidence: 99%

Cyclic stress induced phase transformation in super-bainitic microstructure

et al. 2017

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The effects of cyclic stress loading on the microstructual evolution and tensile properties of a medium-carbon superbainitic steel were investigated. Experimental results show that the cyclic stress can induce the carbon gathering in austenite and phase transformation from film-like retained austenite to twin martensite, which will obviously enhance the tensile strength and the product of tensile strength and ductility. The higher the bainitic transformation temperature, the lower the transformation rate of the retained austenite. The amount and thickness of the film-like retained austenite play an important role during the cyclic stress induced phase transformation.

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Section: Methodsmentioning

confidence: 99%

Cyclic stress induced phase transformation in super-bainitic microstructure

et al. 2017

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“…The retained austenite considerably influences the impact toughness. [23][24][25] The film-like retained austenite can hinder crack propagation effectively, whereas the carbide, as a second phase in the carbide-bearing bainitic steel, easily forms cracks. 26 All these reasons result in higher impact toughness for the carbide-free bainite.…”

Section: Mechanical Properties Of Bainitic Steelsmentioning

confidence: 99%

Study on carbide-bearing and carbide-free bainitic steels and their wear resistance

Long

Zhang

Kang

et al. 2017

Materials Science and Technology

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Carbide-free and carbide-bearing bainitic steels have been obtained. The relationship between the bainitic microstructure and wear resistance has been studied. Results show that carbide-free upper and lower bainitic microstructures obtained in the steel with Si + Al mainly consist of bainitic ferrite and retained austenite. Carbide-bearing upper and lower bainitic microstructures obtained in the steel without Si + Al consist of bainitic ferrite, carbide and trace amounts of retained austenite. The carbide-free bainite exhibits higher strength and toughness than carbide-bearing bainite, especially the toughness. Under lower wear loading, carbide-bearing lower bainite (LB) exhibits higher wear resistance. Under higher wear loading, carbide-free LB exhibits higher wear resistance, which results from the improved surface hardness due to strain-induced martensitic transformation from the retained austenite.

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“…High silicon steels are remarkable materials and notable competitors to AHSSs because of their advantages like low cost and favourable combination of high strength and ductility [4][5][6]. AISI 9254 high silicon steel is one such example, which may be considered as a promising material for automotive applications such as axels, coil springs, stabilizer bars and suspension parts [6,7], both in terms of its properties and low cost as it does not contain expensive alloying elements like Ni, Co, Mo and V. The relatively high Si (about 1.5 wt-%) content of this steel is crucial as an element imparting the tendency to suppress carbide formation [8,9]. As a result of that, the material's microstructure contains carbon-enriched austenite and bainitic ferrite after undergoing an appropriate austempering process.…”

Section: Introductionmentioning

confidence: 99%

Influence of two-step austempering at different temperatures on mechanical and microstructural properties of AISI 9254 high silicon steel

Nalçaci

Baysun

Bahador

et al. 2023

Ironmaking & Steelmaking

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This study was undertaken to understand the effects of two-step austempering treatment on an AISI 9254 high silicon steel towards tailoring the properties as desired while simultaneously employing the benefits of high and low austempering temperatures. The samples were initially austenitized at 850°C for 20 min, followed by austempering in a salt bath at the temperatures of 250-270-290°Cfor 20 min during the first stage. Subsequently, a second stage austempering was carried out by raising the temperature of the salt bath to 300°C at an average heating rate of 0.5°C/min, and the samples were kept in the salt bath for achieving a total austempering time of 120 min including the heating time. A conventional single-stage austempering was also conducted for comparison purposes, in which the austenitization temperature, the austempering temperatures and total time (stage I and stage II, i.e. 120 min) were kept the same for the benchmark samples. In the characterization studies, tensile test, hardness test, XRD analysis, optical microscope and field emission-scanning electron microscope (FE-SEM) equipped with EBSD detector were utilized. The findings of this study indicated that lowering the austempering temperature resulted in refining the structure with a decrease in the amount of austenite. According to the carbon content analysis through XRD patterns, the two-step austempering processes appeared to have considerably increased the carbon content of the austenite irrespective of austempering temperature. The best ultimate tensile strength (U.T.S) of 2194 MPa was achieved in the conventionally austempered sample at the lowest temperature of 250°C, while the best yield strength (Y.S.) of 1753 MPa was reached in the stepped austempered sample initially at 250°C followed by 300°C. In general, two-step austempering process led to a higher yield strength while affecting the ultimate tensile strength and total elongation depending on the austempering temperature.

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Critical isothermal temperature and optimum mechanical behaviour of high Si-containing bainitic steels

Cited by 26 publications

References 23 publications

Cyclic stress induced phase transformation in super-bainitic microstructure

Cyclic stress induced phase transformation in super-bainitic microstructure

Study on carbide-bearing and carbide-free bainitic steels and their wear resistance

Influence of two-step austempering at different temperatures on mechanical and microstructural properties of AISI 9254 high silicon steel

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