Mechanical properties and austenite stability in hot-rolled 0.2C–1.6/3.2Al–6Mn–Fe TRIP steel

Li, Z.C.; Ding, Hua; Cai, Z.H.

doi:10.1016/j.msea.2015.05.061

Cited by 83 publications

(27 citation statements)

References 35 publications

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“…When the manganese content rises, the initial microstructure (after cold rolling) changes to low-C martensite [2]. Medium-Mn steels can be obtained as cold-rolled [5] or hot-rolled [6] sheets. For lightweight applications in the automotive industry, cold-rolled coated sheet products are of particular interest.…”

Section: Introductionmentioning

confidence: 99%

“…After the hot-working and cooling to room temperature (a quenching step), the martensitic or ferritic-martensitic microstructure is subjected to intercritical annealing. The fine-grained lath-type ferrite-austenite mixture is formed under such annealing conditions [6]. For such small grain sizes of the austenite and its Mn contents higher than 7%, the stable austenite is retained at room temperature.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Deformation Temperature on the Portevin-Le Chatelier Effect in Medium-Mn Steel

Grzegorczyk

Kozłowska

Morawiec

et al. 2018

Metals

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Experimental investigations of the plastic instability phenomenon in a hot-rolled medium manganese steel were performed. The effects of tensile deformation in a temperature range of 20-140 • C on the microstructure, mechanical properties, and flow stress serrations were analyzed. The Portevin-Le Chatelier (PLC) phenomenon was observed for the specimens deformed at 60 • C, 100 • C, and 140 • C. It was found that the deformation temperature substantially affects the type and intensity of serrations. The type of serration was changed at different deformation temperatures. The phenomenon was not observed at room temperature. The plastic instability occurring for the steel deformed at 60 • C was detected for lower strain levels than for the specimens deformed at 100 • C and 140 • C. The increase of the deformation temperature to 100 • C and 140 • C results in shifting the PLC effect to a post uniform deformation range. The complex issues related to the interaction of work hardening, the transformation induced plasticity (TRIP) effect, and the PLC effect stimulated by the deformation temperature were addressed. stabilize the retained austenite through its carbon enrichment [8]. An alternative approach is to apply thermomechanical processing (TMP) as direct one-step cooling following the hot rolling. The TMP has the potential for energy savings and high productivity due to the elimination of the need for successive heating [9][10][11]. Chemical composition and processing parameters are designed to obtain the optimal TRIP (Transformation Induced Plasticity) effect, which ensures superior mechanical properties [12,13].Besides the many advantages of this group of steels, some problems during their processing can occur. Medium manganese steels [14-17] and high manganese steels [18][19][20] are prone to plastic instabilities phenomena associated with a serrated flow behavior-Portevin-Le Chatelier (PLC) effect and the appearance of Lüders bands. This is especially the case for cold-rolled steel sheets [21]. Moreover, it critically depends on the carbon level. With a higher C content, a pronounced effect is more visible. The heterogeneous deformation related to the increase in flow stress can lead to numerous cracks during the forming of sheets. Moreover, delayed cracking after deep drawing can appear. Delayed cracking is mostly observed in high-Mn content steels of the high austenite volume fraction. With the increased volume fraction of (retained) austenite, hydrogen embrittlement may be a more important concern. TWIP steels in the last decades have displayed important delayed cracking, which was industrially solved by decreasing the C content, Al alloying, and/or metallurgical processing [22,23]. Medium Mn steels have a less pronounced problem of delayed cracking compared to high-Mn steels [24,25].The PLC effect is commonly known as characteristic serrations which can be observed on a strain-stress curve during a tensile test. The PLC effect has not been fully characterized yet. However, some correlations between the TRIP a...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of Deformation Temperature on the Portevin-Le Chatelier Effect in Medium-Mn Steel

Grzegorczyk

Kozłowska

Morawiec

et al. 2018

Metals

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“…2, some blocky austenite in 2Al and 4Al samples was divided by α-ferrite into lamellar morphology with different thickness and length. It was further confirmed that Mn and C were non-uniformly distributed in lamellar austenite leading to discontinuous TRIP effect, which contributed to enhancement of strength and WH[21,[31][32][33]. However, based on the EPMA / EDS results, Mn and C were distributed uniformly in austenite in 6Al steel.…”

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confidence: 85%

Microstructure and deformation behavior of the hot-rolled medium manganese steels with varying aluminum-content

Cai

Ding

et al. 2016

Materials Science and Engineering: A

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We elucidate here the mechanistic contribution of the interplay between microstructural constituents and plastic deformation behavior in hot-rolled Fe-0.2C-11Mn-xAl steels containing 2-6 wt.% Al. The decrease in austenite fraction with increase in Al-content was accompanied by decrease in tensile strength, while the δ-ferrite content and ductility increased. 2Al steel was characterized by ultrahigh ultimate tensile strength (UTS) of 1407 MPa, while 6Al steel exhibited extremely high total elongation (TE) of 65%. The superior ductility in 6Al steel is attributed to cumulative contribution of transformation induced plasticity (TRIP) effect and twinning induced plasticity (TWIP) effect. The increase in soft δ-ferrite phase with low microhardness led to increase in TE and decrease in UTS and work hardening rate.

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“…The WHR decreased rapidly in stage 1 (S1), remained rather stable until its fluctuation in S2, then varied considerably as true strain increased in S3, and finally decreased in a serrated manner in S4. The WHR performance in four stages can be explained by: soft phase ferrite underwent considerable yield deformation in the early stage of plastic deformation (S1) [22,23]; there was a competition between the strength increasing effect caused by the TRIP effect of retained austenite and the softening effect of ferrite deformation (S2) [24]; the progressive TRIP effect of retained austenite caused the strength increasing effect to overcome the softening effect of ferrite deformation (S3) [25][26][27][28]; and the austenite TRIP effect was exhausted due to its negation, similar to S1, at the end of the strain (S4). It was noteworthy that the WHR peaks nearly disappeared with serrated behavior in S4.…”

Section: Austenite Stability and Work-hardening Behavoirmentioning

confidence: 99%

Microstructure-Tensile Properties Relationship and Austenite Stability of a Nb-Mo Micro-Alloyed Medium-Mn TRIP Steel

Chun-quan

Qi-chun

Xue

et al. 2018

Metals

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This study investigated the microstructure-tensile properties relationship and the retained austenite room temperature stability of a Nb and Mo micro-alloyed medium manganese transformation induced plasticity (TRIP) steel. A number of findings were obtained. Most importantly, the steel after being processed by quenching and tempering (Q & T) exhibited excellent tensile properties, i.e., the strength of 878-1373 MPa, the ductility of 18-40% Mo, and Nb microalloying served to control the fraction of retained austenite and to improve tensile strength by fine grain strengthening. Excellent tensile properties were attributable to the large amount of retained austenite which produced a discontinuous TRIP effect. This effect led to the production a large amount of martensite which relieved the stress concentration, contributing to the coordinated deformation between the phases and thus improving the deformability of the steel. Additionally, the differences in Mn and C contents led to varying degrees of austenite stability and the length of the Lüders band decreased as the intercritical annealing temperature increased. The micro-alloyed medium manganese steel experimented on our study showed considerable improvement in tensile properties in comparison with the 5Mn-0.1C medium manganese steel in previous studies.

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Mechanical properties and austenite stability in hot-rolled 0.2C–1.6/3.2Al–6Mn–Fe TRIP steel

Cited by 83 publications

References 35 publications

Effect of Deformation Temperature on the Portevin-Le Chatelier Effect in Medium-Mn Steel

Effect of Deformation Temperature on the Portevin-Le Chatelier Effect in Medium-Mn Steel

Microstructure and deformation behavior of the hot-rolled medium manganese steels with varying aluminum-content

Microstructure-Tensile Properties Relationship and Austenite Stability of a Nb-Mo Micro-Alloyed Medium-Mn TRIP Steel

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