scholarly journals The Influence of Warm Rolling Reduction on Microstructure Evolution, Tensile Deformation Mechanism and Mechanical Properties of an Fe-30Mn-4Si-2Al TRIP/TWIP Steel

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 742 ◽  
Author(s):  
Yanchun Dong ◽  
Zhilin Sun ◽  
Hao Xia ◽  
Jianhang Feng ◽  
Jiejie Du ◽  
...  

The effects of warm rolling reduction ratio ranging from 20% to 55% on microstructure evolution, the tensile deformation mechanism, and the associated mechanical properties of an Fe-30Mn-4Si-2Al TRIP/TWIP steel were studied. The warm rolling process resulted in the formation and proliferation of sub-structure, comprising dislocations, deformation twins as well as shear bands, and the densities of dislocation and twins were raised along with the increase in rolling reduction. The investigated steel, with a fully recrystallized state, exhibited a single ε-TRIP effect during the room temperature tensile deformation, on top of dislocation glide. However, the formation and growth of twin lamellae and ε-martensite were detected simultaneously during tensile deformation of the warm rolled specimen with rolling reduction of 35%, leading to a good balance between high yield strength of 785 MPa, good total ductility of 44%, and high work hardening rate. As the rolling reduction increased to 55%, the specimen revealed a relatively low work hardening rate, due to the high dislocation density, and dislocation glide was the main deformation mechanism. As a result, a tensile deformation mechanism that started from a single ε-martensitic transformation moved to a bi-mode of ε-martensitic transformation accompanied with deformation twinning, and finally to dislocation glide with the increasing warm rolling reduction was proposed.

2010 ◽  
Vol 667-669 ◽  
pp. 161-166 ◽  
Author(s):  
Nikolay Lopatin ◽  
Grigoriy Diakonov ◽  
Olga Pleshakova

This article focuses on the effect of combine rolling processes on structure and mechanical properties of the commercially pure Ti rods. The finite element model had being made. The analysis of strain state at the screw and shape rolling was done. The analysis of microstructure evolution at the warm rolling was completed.


2012 ◽  
Vol 83 (4) ◽  
pp. 346-351 ◽  
Author(s):  
Mi Zhenli ◽  
Tang Di ◽  
Zhao Aimin ◽  
Jiang Haitao

2011 ◽  
Vol 686 ◽  
pp. 90-95 ◽  
Author(s):  
Bin Jiang ◽  
Qing Shan Yang ◽  
Liang Gao ◽  
Fu Sheng Pan

The microstructure evolution of the extruded Mg-9Li-1Al (LA91) during rolling was investigated taking account of effects of different routes including hot rolling, and cross rolling. The rolling parameters were suggested by thermal compression testing. As a result, the suggested rolling parameters were 250°C and 1.0s-1. Transverse hot rolling would bring a finer microstructure to the as-rolled LA91 sheet. With the enhancement of the rolling reduction during unidirectional hot rolling the α-Mg phase became granular or short rod-like from long strip-like. Transverse + longitudinal hot rolling would improve the microstructure and was a better cross rolling route by which the strength and the elongation of the cross rolled LA91 sheet reached 243MPa and 20% respectively. The over-aging existed in the cross rolled LA91 sheets.


2020 ◽  
Vol 10 (4) ◽  
pp. 503-513
Author(s):  
Sohail Ahmad ◽  
Xiangyu Wang ◽  
Liming Fu ◽  
Javed Ahmad ◽  
Waseem Abbas ◽  
...  

A dual phase (martensite–austenite) low carbon nickel-manganese transformation-induced plasticity (TRIP) steel was fabricated by heavily warm rolling (HWR), and the effect of annealing on the phase fraction, mechanical properties and tensile deformation behavior of the heavily warm rolled (HWRed) steel was investigated. The results showed that the reverse transformation of γ-austenite from α′-martensite occurs and that the γ-austenite volume fraction (VA) decreases from 91% to 55% as the annealing temperature increases from 400 °C to 800 °C, respectively. The HWRed steel annealed at 400 °C exhibits a high strength-high ductility combination with yield strength of 706 MPa, ultimate tensile strength (UTS) of 1573 MPa, total elongation (TEL) of 21.6%, and the product of the strength and elongation (PSE: UTS×TEL) is 34 GPa%. These excellent mechanical properties are principally attributed to the formation of a large volume fraction of austenite (γ) by the reverse transformation and subsequent TRIP effect during tensile deformation. It was found that the HWRed and annealed steels exhibit a special tensile behavior with a large yielding strain followed by pronounced strain hardening. The tensile curve can be readily divided into three obviously different stages. The strain-induced martensite (SIM) transformation (γ -α′) occurs in the early yielding deformation stage and in the intermediate rapidly hardening deformation stage, indicating that the TRIP effect dominates the process of these two stages. However, the retained γ-austenite remains very stable, and no TRIP effect is observed in the final hardening deformation stage. The load-unload reload (LUR) test was performed to evaluate the back stress (σb) hardening effect during tensile testing. It is believed that the pronounced strain hardening behavior after yielding is mainly associated with the σb enhancement induced by the strain partitioning between the soft retained γ-austenite and the hard α′-martensite due to the SIM transformation during tensile deformation.


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