Microstructure and texture evolution during cold rolling and annealing of a high Mn TWIP steel

Bracke, Lieven; Verbeken, Kim; Kestens, Léo; Penning, Jan

doi:10.1016/j.actamat.2008.11.036

Cited by 318 publications

(160 citation statements)

References 33 publications

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“…They confirm that due to high chemical composition in high-Mn steels; expulsion occurred earlier and high welding current increases the cracking tendency because of increasing nugget pressure and the tensile stress in heat affected zone (HAZ) during cooling [11]. Deformation behavior of high-manganese TWIP steels has been widely studied in relation to microstructure and texture evolution by microscopy analysis scanning electron microscope (SEM) and transmission electron microscopy (TEM), X-ray diffraction (XRD) measurements [2,[12][13][14][15][16][17][18][19][20][21]. However, weldability of such steel has been poorly investigated.…”

Section: Introductionmentioning

confidence: 99%

Properties of Resistance Spot-Welded TWIP Steels

Zeytin

Emre

Kaçar

2017

Metals

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High manganese TWIP (twinning-induced plasticity) steels are particularly attractive for automotive applications because of their exceptional properties of strength combined with an excellent ductility. However, the microstructure and properties of TWIP steels are affected by excessive thermal cycles, such as welding and heat treatment. This paper deals with characterization and understanding the effect of welding current and time on the mechanical properties and microstructure of the resistance spot welded TWIP steel. For this purpose, weld nugget diameter was evaluated and the hardness, tensile shear strength of the weldment, and failure mode of samples were also determined. It has been found that the tensile shear strength of the samples increased with increasing welding current and welding time without expulsion, which reduces the strength of the weldment. Tensile shear samples failed by a partial interfacial fracture mode for low-heat input welds. The pullout fractures were observed with a sufficient heat input without expulsion.

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Section: Introductionmentioning

confidence: 99%

Properties of Resistance Spot-Welded TWIP Steels

Zeytin

Emre

Kaçar

2017

Metals

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“…The high yield strength comes from the large increase of dislocation activity forming a large number of subgrains together with the interaction with mechanical twins [32,33]. Despite the large SFE values at 300°C [5,9], mechanical twinning has been repeatedly observed in a large number of austenite grains for the present TWIP steel, in the same way than in the other TWIP steels processed by ECAP [16,17].…”

Section: Discussionmentioning

confidence: 57%

“…This texture component is usually found in hot rolled FCC metals [29] and it has also been described for low SFE metals in the as-rolled condition [30]. For the specific case of TWIP steels, the evolution of Brass-type rolling texture has also been intensively studied [31][32][33]. In this case, after the last annealing step and the increase of annealing twins, the presence of Goss and β-fiber texture components have practically disappeared and the brass texture components have been reinforced.…”

Section: Texture Analysismentioning

confidence: 99%

Equal channel angular pressing of a TWIP steel: microstructure and mechanical response

et al. 2017

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A Fe-20.1Mn-1.23Si-1.72Al-0.5C TWIP steel with ultra-fine grain structure was successfully processed through Equal Channel Angular Pressing (ECAP) at warm temperature up to four passes following the BC route. The microstructure evolution was characterized by Electron Back Scattered Diffraction (EBSD) to obtain the grain maps, which revealed an obvious reduction of grain size, as well as a decrease of the twin fraction, with increasing number of ECAP passes. The texture evolution during ECAP was analyzed by Orientation Distribution Function (ODF). The results show that the annealed material presents Brass (B) as dominant component. After ECAP, the one pass sample presents A1 * and A2 * as the strongest components, while the two passes and four passes samples change gradually towardcomponents. TEM analysis shows that all samples present twins. The twin thickness is reduced with increasing the number of ECAP passes. Nano-twins, as a result of secondary twinning, are also observed in the one and two passes samples. In the four passes sample the microstructure is extensively refined by the joint action of ultra-fine subgrains, grains and twins. The mechanical behavior was studied by tensile samples and it was found that the yield strength and the ultimate tensile strength are significantly enhanced at increasing number of ECAP passes. Although the ductility and strain hardening capability are reduced with ECAP process, the present TWIP steel shows significant uniform deformation periods with positive work-hardening rates.

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“…This process requires very high stresses with specific orientations. Glide sources are therefore less probable source of twins, but Bracke et al (2009), who studied twinning in Fe-22%Mn-0.5%C TWIP steel by means of TEM, support a model for the creation of a three layer stacking fault acting as a twin nucleus. They report a critical shear stress for twinning to be 89MPa.…”

Section: Wwwintechopencommentioning

confidence: 99%