Third generation of AHSS with increased fraction of retained austenite for the automotive industry

Grajcar, A.; Kuziak, R.; Zalecki, W.

doi:10.1016/j.acme.2012.06.011

Cited by 124 publications

(74 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…4b). The largest grains of c phase are usually located at the boundaries of individual sheaves of bainite and undergo martensitic transformation due to their higher M s temperature [9,19]. The occurrence of retained austenite is also confirmed by X-ray examination.…”

Section: Thermodynamic Equilibrium Diagramsmentioning

confidence: 79%

“…Pearlite is delayed to long times and the bainitic field is left-shifted. The real CCT diagram included elsewhere [9] indicates that a ferrite fraction is very low and a pearlitic transformation is efficiently avoided up to 1,000 s. These conditions are very desired in respect of the thermal stabilization of retained austenite.…”

Section: Thermodynamic Equilibrium Diagramsmentioning

confidence: 99%

“…The research has been performed on newly developed 3Mn-1.5Al type steel with the following chemical composition: 0.17 % C, 3.3 % Mn, 1.7 % Al, 0.22 % Si, 0.23 % Mo, 0.014 % S and 0.01 % P. Increased concentration of Mn is to stabilize retained austenite and addition of Al prevents precipitation of carbides during a bainitic transformation, favouring formation of carbide-free bainite [8,9,18]. A 25-kg ingot was produced by vacuum induction melting in the Balzers VSG-50 furnace.…”

Section: Methodsmentioning

confidence: 99%

“…This phase ensures a required ductility level by its strain-induced martensitic transformation during cold forming operations. Recently, a high amount of retained austenite is obtained in different bainitic alloys containing from 1.5 up to 8 mass% Mn, being a main austenite stabilizer [8][9][10][11][12][13][14]. These steels are dedicated to the automotive industry for different crash-relevant elements, especially in the side zone of a car (B-pillars, roof rails, side-impact beams, etc.).…”

Section: Introductionmentioning

confidence: 99%

“…Advanced ultra-high-strength steels contain a higher fraction of hard phases, i.e. acicular ferrite, bainite or martensite [7][8][9][10] compared to AHSS containing polygonal ferrite as a matrix. A key microstructural constituent of advanced multiphase steels is retained austenite with the amount from 10 to 30 %.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Dilatometric study of phase transformations in advanced high-strength bainitic steel

Grajcar

Zalecki

Skrzypczyk

et al. 2014

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

The work deals with dilatometric studies of a new-developed advanced high-strength bainitic 3Mn-1.5Al steel. Ferritic, bainitic and martensitic phase transformations are investigated in detail in respect of their temperature range forming and microstructures produced under various conditions of both continuous and isothermal cooling. The equilibrium temperatures of A e1 and A e3 and phase composition of the investigated steel were initially calculated whereas critical temperatures of A c1 and A c3 as well as the decomposition of retained austenite were determined upon heating. The major tests consisted of controlled cooling of undeformed or plastically deformed austenite using the dilatometer within the cooling rate range of 2-0.5°C s -1 . The effects of the cooling rate and deformation at temperatures of 900 and 1,050°C on the phase transformation behaviour and microstructure were explained. The final experiment was carried out using a thermo-mechanical simulator under conditions of multistep deformation and isothermal holding of the steel at 400°C. Microstructural features were revealed using light microscopy and scanning electron microscopy techniques.

show abstract

Section: Thermodynamic Equilibrium Diagramsmentioning

confidence: 79%

Section: Thermodynamic Equilibrium Diagramsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Dilatometric study of phase transformations in advanced high-strength bainitic steel

Grajcar

Zalecki

Skrzypczyk

et al. 2014

J Therm Anal Calorim

Self Cite

View full text Add to dashboard Cite

show abstract

Phase Evolution and Mechanical Behavior of 0.36 wt% C High Strength TRIP‐Assisted Steel

Ghosh¹,

Chattopadhyay²

2012

steel research int.

View full text Add to dashboard Cite

Phase evolution in a 0.36 wt% C steel has been studied by thermodynamic calculation and dilatometric analysis with an aim to achieve high strength TRIP‐assisted steel with bainitic microstructure. The equilibrium phase fraction calculated as the function of temperature indicated the formation of δ‐ferrite (≈98%) at 1417°C. In contrast, similar calculation under para‐equilibrium condition exhibited transformation of δ‐ferrite to austenite at the temperature below 1300°C. During further cooling two‐phase (α+γ) microstructure has been found to be stable at the intercritical temperature range. The experimentally determined CCT diagram has revealed that adequate hardenability is achievable in the steel under continuous cooling condition at cooling rate >5°C s−1. In view of the aforesaid results, the steel has been hot rolled and subjected to different process schedule conducive to the evolution of bainitic microstructure. The hot rolled steel has exhibited reasonably good tensile properties. However, cold deformation of the hot rolled sample followed by intercritical annealing and subsequent isothermal bainitic transformation has resulted in high strength (>1000 MPa) with attractive elongation due to the favorable work hardening condition during plastic deformation offered by the multiphase microstructure.

show abstract

Effect of Finishing Hot‐Working Temperature on Microstructure of Thermomechanically Processed Mn–Al Multiphase Steels

Grajcar

Skrzypczyk

Kuziak

et al. 2014

steel research int.

View full text Add to dashboard Cite

The study was devoted to the hot‐working behavior and the microstructure evolution of four thermomechanically processed Mn–Al‐alloyed multiphase steels. Determination of the hot deformation resistance of investigated steels was carried out on the basis of continuous compression, double‐hit compression, and seven‐step compression tests simulating conditions of hot strip rolling. The experiments were carried out using the Gleeble 3800 thermomechanical simulator. The physical simulation of hot strip rolling consisted of seven deformation steps characterized by decreasing strain, temperature, and interpass time whereas the strain rate values were gradually increased. A special attention was paid to the effect of Nb microaddition on the hot‐working behavior and microstructure evolution with the finishing hot‐working temperature varying in a range from 950 to 750°C. Morphological features of a bainite‐based matrix and retained austenite were identified using light microscopy and scanning electron microscopy techniques. A fraction of retained austenite was determined by X‐ray diffraction. The increase in the Mn content increases the softening kinetics of austenite. It was also found that the best conditions for thermal stabilization of retained austenite occur at 950°C for the steels containing 3% Mn.

show abstract

Third generation of AHSS with increased fraction of retained austenite for the automotive industry

Cited by 124 publications

References 15 publications

Dilatometric study of phase transformations in advanced high-strength bainitic steel

Dilatometric study of phase transformations in advanced high-strength bainitic steel

Phase Evolution and Mechanical Behavior of 0.36 wt% C High Strength TRIP‐Assisted Steel

Effect of Finishing Hot‐Working Temperature on Microstructure of Thermomechanically Processed Mn–Al Multiphase Steels

Contact Info

Product

Resources

About