Strain hardening requires what kind of strain

The strain required for martensitic transformation is lower in the A steel than in the A steel, while the amount of transformation is larger, in spite of the less TWIP, thereby leading to the higher strain-hardening rate in the A steel.

The rapid TRIP mechanism in the Stage B is closely related with the deterioration of austenite stability, and thus the A steel shows the higher tensile strength and lower elongation than the A steel. When considering the high strain hardening without plastic instability, the austenite stability of the A steel is adequately optimized for structural applications.

Recently, high-Mn TWIP steels have been nominated as promising automotive steels having excellent combination of strength and ductility 40 , 41 , 42 , 43 , 44 , These austenitic microstructures show rather low yield strength because of their inherent characteristics and grain coarsening 46 , In this respect, the duplex microstructure has been regarded as a desirable concept because of its advantages of high yield strength.

In addition, the high Mn content in TWIP steels often causes problems such as reduced productivity due to temperature drop of the molten steel during steel-making, nozzle blocking during continuous casting, cracking during hot rolling, and easy surface oxidation of rolled steel products Comparison of room-temperature tensile properties of the present Fe In conclusion, when considering the strength and elongation simultaneously, the austenite having an appropriate stability is desirable.

In the duplex microstructures, the alloying partitioning due to variation in austenite fraction should be importantly considered. As aforementioned in the section of alloy design concept, the indirect decrease in austenite stability due to the austenite fraction increased by the increased Mn and decreased Al contents acts as an effective strategy of alloy design.

Since the austenite greatly affects tensile properties, depending on its stability, it does not sufficiently contribute the ductility improvement in the case of the A steel having very low stability. In order to obtain the best combination of strength and ductility, the formation of austenite having an appropriate stability is essentially needed, and can be achieved when about 55 vol. This excellent combination of strength and ductility is basically attributed to multiple-stage deformation mechanisms, i.

However, this is not desirable for the issue of high strain hardening rate generally required in deformability, fracture resistance, and energy absorption capability. With respect to this issue, the TRIP mechanism prevails more actively in the A steel than the TWIP mechanism as the austenite stability is somewhat lower than that of the A steel.

Since the A steel shows outstanding tensile properties as well as reduced density, they give a promise for automotive applications to highly-deformable high-strength sheets and structural reinforcement components requiring high stiffness. The lightweight steel, whose chemical composition was Fe Effects of Al addition on weight reduction are attributed to lattice expansion and low atomic weight of substitutional solution The addition of 1 wt.

Their volume fractions were measured using XRD analysis Because of the difficulty in precise measurement of C, the C content was measured by the XRD method The tensile tests were conducted three times for each datum point. The data that support the findings of this study are available from the corresponding author upon reasonable request. Ritzkowski, M. Controlling greenhouse gas emissions through landfill in situ aeration. Gas Control 1 , —, doi: Kaygusuz, K.

Energy and environmental issues relating to greenhouse gas emissions for sustainable development in Turkey. Energy Rev. Article Google Scholar. Hashimoto, K. Global CO 2 recycling — novel materials and prospect for prevention of global warming and abundant energy supply.

A , —, doi: Mayyasa, A. Design for sustainability in automotive industry: a comprehensive review. Advanced high strength steels for automotive industry.

Akisue, O. Steel Tech. Rep 57 , 11—15 Google Scholar. Rana, R. High Modulus Steels. Frommeyer, G. Steel Res. Sohn, S. Microstructural analysis of cracking phenomenon occurring during cold rolling of 0. Low-density low-carbon Fe-Al ferritic steels. Mater 68 , —, doi: Hwang, S. Tensile deformation of a duplex FeMn-9Al Kim, S. Brittle intermetallic compound makes ultrastrong low-density steel with large ductility. Nature , 77—79, doi: Raabe, D.

Alloy design, combinational synthesis, and microstructure-property relations for low-density Fe-Mn-Al-C austenitic steels. JOM 66 , —, doi: Zargaran, A. Effect of C content on the microstructure and tensile properties of lightweight ferritic Fe-8Al-5Mn Gutierrez-Urrutia, I. Multistage strain hardening through dislocation substructure and twinning in a high strength and ductile weight-reduced Fe—Mn—Al—C steel.

Acta Mater. Park, S. Effect of second phase on the deformation and fracture behavior of multiphase low-density steels. Yang, F. Tensile deformation of low density duplex Fe-Mn-Al-C steel. Wu, Z. Microstructural evolution and strain hardening behavior during plastic deformation of FeMn-8Al Kim, M. Korean J. Mater 53 , —, doi: De Cooman, B. Structure-properties relationship in TRIP steels containing carbide-free bainite.

Solid State Mater. Tirumalasetty, G. Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel. Gibbs, P. Austenite stability effects on tensile behavior of manganese-enriched-austenite transformation-induced plasticity steel. A 42 , —, doi: Ryoo, K. Seo, C. Deformation behavior of ferrite-austenite duplex lightweight Fe-Mn-Al-C steel. Bouaziz, O. High manganese austenitic twinning induced plasticity steels: A review of the microstructure properties relationships.

Gupta, R. Strain hardening in aerospace alloys. ISIJ Int. Lee, C. Coupled strengthening in a medium manganese lightweight steel with an inhomogeneously grained structure of austenite. Jo, M. Determination of the deformation mechanism of Fe-Mn alloys. Lee, S. A 46 , —, doi: Ding, H.

Sundman, B. The Thermo-Calc databank system. Calphad 9 , —, doi: Chin, K. Thermodynamic calculation on the stability of Fe,Mn 3 AlC carbide in high aluminum steels. Alloys Compd. Song, H. Effect of austenite stability on microstructural evolution and tensile properties in intercritically annealed medium-Mn lightweight steels.

A 47 , —, doi: Kim, H. Fe-Al-Mn-C lightweight structural alloys: a review on the microstructures and mechanical properties. Jimenez-Melero, E. Martensitic transformation of individual grains in low-alloyed TRIP steels. Mater 56 , —, doi: Mahieu, J. Phase transformation and mechanical properties of si-free CMnAl transformation-induced plasticity-aided steel. A 33A , —, doi: Jin, J. Strain hardening behavior of a FeMn Santos, D.

Effect of annealing on the microstructure and mechanical properties of cold rolled FeMn-3Al-2Si-1Ni Jeong, J. In situ neutron diffraction study of the microstructure and tensile deformation behavior in Al-added high manganese austenitic steels. Plasticity 16 , —, doi: Dini, G. Tensile deformation behavior of high manganese austenitic steel: The role of grain size. Choi, K. Effect of aging on the microstructure and deformation behavior of austenite base lightweight FeMn-9Al Mater 63 , —, doi: Sutou, Y.

High-strength FeMn-Al-C based alloys with low density. Suh, D. Influence of Al on the microstructural evolution and mechanical behavior of low-carbon, manganese transformation-induced-plasticity steel. A 41A , —, doi: Babu, S. In-situ observations of lattice parameter fluctuations in austenite and transformation to bainite. A 36A , —, doi: Download references. This work was supported by the Ministry of Knowledge Economy under a grant No. By controlling these processes of deformation and heat treatment, we are able to process the material into a usable shape, yet still improve and control the properties.

Unable to display preview. Download preview PDF. Skip to main content. This service is more advanced with JavaScript available. Advertisement Hide. Strain Hardening and Annealing. Authors Authors and affiliations Donald R. This process is experimental and the keywords may be updated as the learning algorithm improves.