Influence of the Al and Mn content on the structure-property relationship in density reduced TRIP-assisted sheet steels

Kaar, Simone; Križan, Daniel; Schwabe, Jeremia; Hofmann, Harald; Hebesberger, T.; Commenda, C.; Samek, Ludovic

doi:10.1016/j.msea.2018.08.066

Cited by 32 publications

(22 citation statements)

References 39 publications

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“…The values of uniform elongation, which are 11.5% and 7.6%, respectively for 3Mn-1.5Al and 5Mn-1.5Al steels ( Figure 6) depend also on the strain hardening rate. Kaar et al [28] reported that too high aluminum and manganese contents deteriorate the plasticity of the TRIP steels at increased strengths. Considering the UE/TE ratios which are 0.74 and 0.66 for the steels of lower and higher Mn contents respectively, it can be concluded that 3Mn-1.5Al steel is more susceptible to uniform straining.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

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Microstructure–Property Relationships in Thermomechanically Processed Medium-Mn Steels with High Al Content

Grajcar

Kilarski²,

Kozłowska

2018

Metals

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Detailed studies on microstructure-property relationships of thermomechanically processed medium-Mn steels with various manganese contents were carried out. Microscopic techniques of different resolution (LM, SEM, TEM) and X-Ray diffraction methods were applied. Static tensile tests were performed to characterize mechanical properties of the investigated steels and to determine the tendency of retained austenite to strain-induced martensitic transformation. Obtained results allowed to characterize the microstructural aspects of strain-induced martensitic transformation and its effect on the mechanical properties. It was found that the mechanical stability of retained austenite depends significantly on the manganese content. An increase in manganese content from 3.3% to 4.7% has a significant impact on the microstructure, stability of γ phase and mechanical properties of the investigated steels. The initial amount of retained austenite was higher for the 3Mn-1.5Al steel in comparison to 5Mn-1.5%Al steel-17% and 11%, respectively. The mechanical stability of retained austenite is significantly affected by the morphology of this phase. case, the phase transformation kinetics depends significantly on the austenite deformation degree [5,8,9]. In case of the first generation AHSSs, the main advantage of the TMP is the ability to refine the ferrite grain size by controlling the austenite pancaking [10,11]. Moreover, the thermomechanical treatment can increase the amount of retained austenite to obtain the optimal TRIP (TRansformation Induced Plasticity) effect [12,13]. In case of medium manganese steels (third generation AHSS), the TMP is also a good alternative for the cold-rolling process [14][15][16]. However, most publications on medium-Mn steels concern the cold-rolling process and subsequent inter-critical heat treatment.Cold-rolled medium-Mn TRIP steels are susceptible to plastic instabilities associated with dynamic strain aging (DSA) and serrated flow (PLC-Portevin-Le Chatelier) effects due to the heat treatment required after cold-rolling. From a technological point of view, the PLC and DSA effects must be avoided. The DSA phenomenon gives rise to non-homogeneous plastic flow during the sheet-forming processes and may lead to surface defects on formed parts [17][18][19]. Our previous reports on thermomechanically processed medium-Mn sheet steels indicate that the problem can be avoided [7].Newly developed fine-grained ferrite-austenite or bainitie-austenite steels contain manganese in a range of 3-12%, while carbon content is ca. 0.1-0.2%. These steels contain also aluminum and silicon (1-3%) additions which delay the carbides formation during the bainitic transformation. The increased Mn amount leads to obtain the high fraction of retained austenite (~10-30%). The Mn addition also increases the carbon solubility and lowers the cementite precipitation temperature [20][21][22]. Al is added to partially replace silicon due to the problems related to galvanizing, hot-rolling and welding [23][24][25]. However, Gir...

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Section: Mechanical Propertiesmentioning

confidence: 99%

“…Al and Mn additions affect the mechanical stability of retained austenite too. Kaar et al [28] reported that too high aluminum and manganese contents deteriorate the plasticity of the TRIP steels. Mo can be also added to increase strength by its strong solid solution effect.…”

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confidence: 99%

Microstructure–Property Relationships in Thermomechanically Processed Medium-Mn Steels with High Al Content

Grajcar

Kilarski²,

Kozłowska

2018

Metals

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“…It is related to the fact, that these microadditions improve the properties by enhancing the strength and grain refinement [8][9][10][11][12][13][14][15][16][17][18][19]21]. It is well known that the amount of retained austenite was decreasing as a result of plastic deformation [1][2][3][4][5][6][7][8][9]. However, the kinetics of TRIP effect is a complex issue and it depends on several factors (i.e., chemical composition, morphology, and grain size of RA).…”

Section: Discussionmentioning

confidence: 99%

“…Haidemenopoulos et al [6] fitted a mathematical model to available experimental data regarding the evolution of martensite as a function of strain for several TRIP steels. The progressive TRIP effect in hot-rolled sheet steels was investigated rarely [7,8].…”

Section: Introductionmentioning

confidence: 99%

Quantitative Analysis of Microstructure Evolution in Hot-Rolled Multiphase Steel Subjected to Interrupted Tensile Test

Grajcar

Kozłowska

Radwański

et al. 2019

Metals

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A quantitative analysis of the microstructure evolution in thermomechanically processed Si-Al multiphase steel with Nb and Ti microadditions was performed in the study. The tendency of strain-induced martensitic transformation of retained austenite was analyzed during a tensile test interrupted at incremental strain levels. Optical micrographs and electron backscatter diffraction (EBSD) maps were obtained at each deformation step. The quantitative analysis of the martensitic transformation progress as a function of strain was performed. The results showed that the stability of retained austenite is mostly related to its grain size and morphology. Large, blocky-type grains of retained austenite located in a ferritic matrix easily transformed into martensite during an initial step of straining. The highest mechanical stability showed small austenitic grains and thin layers located in bainitic islands. It was found that the extent of martensitic transformation decreased as the deformation level increased.

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“…It is approximately 12.6% lighter than that without the aluminum addition, which has a density of 7.8145 × 10 3 kg/m 3 . Many studies have been reported on mechanical deformation properties [5,6], microstructures [7,8], and properties of δ-TRIP steel [9,10]. However, there is an insufficient understanding of the high-temperature crack sensitivity of the δ-TRIP steel.…”

Section: Introductionmentioning

confidence: 99%

High-Temperature Mechanical Properties of 4.5%Al δ-TRIP Steel

2019

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The high-temperature mechanical properties of a 4.5% Al-containing δ-transformation-induced plasticity (TRIP) steel were studied by using the Gleeble 3500 thermomechanical simulator. The zero ductility temperature (ZDT) and the zero strength temperature (ZST) were measured, and the brittle zones were divided. The phase transformation zone was determined by differential scanning calorimetry (DSC). The temperature of the phase transformation and the proportion of the phase were calculated by the Thermo-Calc software. The ZDT and the ZST of the 4.5% Al-containing δ-TRIP steel are 1355 and 1405 °C, respectively. The first brittle zone and the third brittle zone of the steel are 1300–1350 °C and 800–975 °C, respectively. The reason for the embrittlement of the third brittle zone of the 4.5% Al-containing δ-TRIP steel is that the α-ferrite formed at the austenite grain boundary causes the sample to crack along the grain boundary under stress. The ductility of the 4.5% Al-containing δ-TRIP steel decreases first and then increases with the increase of the α-ferrite. When the proportion of the α-ferrite reaches 37%, the reduction of area (RA) of the 4.5% Al-containing δ-TRIP steel is reduced to 44%. The 4.5% Al-containing δ-TRIP steel has good resistance to the high-temperature cracking.

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Influence of the Al and Mn content on the structure-property relationship in density reduced TRIP-assisted sheet steels

Cited by 32 publications

References 39 publications

Microstructure–Property Relationships in Thermomechanically Processed Medium-Mn Steels with High Al Content

Microstructure–Property Relationships in Thermomechanically Processed Medium-Mn Steels with High Al Content

Quantitative Analysis of Microstructure Evolution in Hot-Rolled Multiphase Steel Subjected to Interrupted Tensile Test

High-Temperature Mechanical Properties of 4.5%Al δ-TRIP Steel

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