Papers by Keyword: TRIP

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Authors: Ru Lin Peng, Xiao Peng Liu, Yan Dong Wang, Shu Yan Zhang, Yong Feng Shen, Sten Johansson
Abstract: In-situ neutron diffraction experiments under tensile loading were carried out to study the micromechanical behaviour of two iron-manganese based steels, a TWIP (twinning induced plasticity) steel with 30 wt% Mn and a TRIP steel (transformation induced plasticity) with 20 wt% Mn. The former was loaded to 31.3% strain and the latter to 20% strain. The 30 wt.% Mn steel had a fully austenitic microstructure which remained stable over the loading range studied, while stress induced austenite to α´- and ε-martensite transformations occur in the 20 wt.% Mn steel which initially contained an α´-martensite in addition to the austenite. The evolution of lattice strains under tensile loading differs between the two steels, reflected their different plastic deformation mechanisms. A stronger grain-orientation dependent behaviour is observed during deformation for the 20 wt.% Mn in contrast to the 30wt.% Mn steel.
474
Authors: F.J. Avellaneda, Valentin Miguel-Eguía, Juana Coello, Alberto Martínez, Antonio Calatayud
Abstract: TRIP steels, or Transformed Induced Plasticity steels, have excellent mechanical properties if compared with conventional steels. The highlighted characteristic of these steels is that they modify the microstructure with the deformation process as part of the austenite transforms to martensite, with the consequent change of the material properties. One of the main problems of TRIP steels is strong elastic recovery, or springback, after forming. In this work, the springback phenomenon is evaluated by bending tests and the influence of the variables involved in it is determined. Experimental bending forces do not agree with theoretical predictions that are proposed in the literature. In spite of the bending radius having been considered an influence factor in the process, this work demonstrates that the aforementioned factor has a minor influence, at least for TRIP 800. The factor found to affect material recovery the most was the bending angle.
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Authors: M. Takahashi, A. Uenishi, H. Yoshida, H. Kuriyama
Abstract: There has been a big demand for increased vehicle safety and weight reduction of auto-bodies. An extensive use of high strength steels is one of the ways to answer the requirement. Since the crashworthiness is improved by applications of higher strength steels to crashworthiness conscious structural components, various types of advanced high strength steels have been developed. The crash energy during frontal collisions is absorbed by the buckling and bending deformations of thin wall tube structures of the crushable zone of auto-bodies. In the case of side collision, on the other hand, a limited length of crushable zone requires the components to minimize the deformation during the collision. The lower the strength during press forming, the better the press formability is expected. However, the higher the strength at a collision event, the better the crashworthiness can be obtained. It can, therefore, be concluded that steels with higher strain rate sensitivities are desired. Combinations of soft ferrite phase and other hard phases were found to improve the strain rate sensitivity of flow stresses. Bake hardening is also one of the ways to improve the strain rate sensitivity of flow stresses.
4386
Authors: Stéphane Godet, You Liang He, John J. Jonas, Pascal J. Jacques
Abstract: The orientation relationships that apply to phase transformations in high-performance TRIP and TWIP steels were characterised by orientation imaging and EBSD techniques. The results are presented in the fundamental zones of Rodrigues-Frank space that correspond to the specific phase transformation under consideration (cubic to cubic or cubic to hexagonal). The use of Rodrigues-Frank space enables straightforward comparison to be made with orientation relationships proposed in the literature. The observations indicate that the active slip systems in the parent phase play important roles in variant selection.
4614
Authors: Xiao Bo Wang, Xin Tong Wang, Jian Huang
Abstract: With the improvement of people's living standards, a wide variety of home appliances gradually into the ordinary family. In these appliances, there are many various nonlinear loads, nonlinear loads generated in the process of using a large number of high harmonics, and sold on the market are mostly air switch 50Hz power under conditions of use in accordance with the design, which kinds of air switch is suitable for applications in which high harmonic supply. This article will explore this issue through theoretical research and testing methods.
823
Authors: Ren Shan Yu, Zhen Wei Yang, Tao Jin
Abstract: After an analysis on the shielding failure trip of accidents of two kinds of tower type for JG and ZGUT in 220kA transmission line in Jiujiang,the main causes of shielding failure trip on the JG and ZGUT type tower which the protection angle of middle phase jumper of JG type tower and middle phase wire of ZGUT type tower are too large were summarized.The measures to prevent the JG and ZGUT type tower from shielding failure were proposed in which TH-lightning rod above cross arm of suspension point of the Jumper string of JG ype tower and the middle phase conductor of ZGUT type tower were reasonably installed.The measures prove to be an effective way.
2139
Authors: Arijit Saha Podder, Amritraj Bhanja
Abstract: Mounting energy crisis, stringent emission law and strict safety rules have guided car manufacturers to improve strength/weight ratio of the vehicle, thereby promoting several applications of stainless steels in the car body. Moreover, use of stainless steels also improves aesthetics and minimizes life cycle cost. In automobiles, presently 45-50% of stainless steels are used in exhaust systems. To improve efficiency, complex designs are being used and performance criteria of the material are getting tougher. New techniques such as tube hydroforming are also being explored using austenitic stainless steel for the complicated designs utilizing the benefits of high ductility of these grades. Since corrosion resistance remains fundamental requirement for these applications, selection of grades and stabilizing elements are critical for such applications and depend primarily on operating conditions. Different grades and effect of their composition on elevated temperature strength, creep strength, endurance limit and corrosion resistance are presented. Stainless steels are also being used in other applications such as fuel tank, bumper, chassis for buses and trucks. With the development of new varieties of austenitic, ferritic and martensitic stainless steels, automotive industry is intensively exploring their potential.
731
Authors: Seong Jun Park, Dong Woo Suh, Chang Seok Oh, Sung Joon Kim
Abstract: Low alloy transformation induced plasticity (TRIP) steels have a complex microstructure consisting of ferrite, bainite and retained austenite. Their excellent mechanical properties are ascribed to the martensitic transformation of retained austenite during plastic deformation. In the present contribution, the crystallographic texture of fcc and bcc phases in TRIP steels was measured by means of orientation mapping. The austenite texture was close to a typical rolling texture of fcc metals. For bcc phase, the effects of orientation and grain size on the distribution of pattern quality were investigated. The texture of transformation product phase was separated by grain size. The transformation texture showed stronger α fiber including {113}<110> component than the recrystallization texture. It showed a good agreement with a transformation texture predicted by Kurdjmov-Sachs (KS) relationship without any variant selection.
1423
Authors: Masayuki Wakita, Yoshitaka Adachi, Yo Tomota
Abstract: This study aims at examining thermomechanical controlled process to realize ultrafine TRIP-aided multi-phase microstructures in low carbon steels. Heavy deformation at a supercooled austenite region was found to lead the formation of 2 μm ferrite as well as retained austenite with high volume fraction. The morphology of retained austenite was changed from film-like shape to granular shape with lowering finish rolling temperature in austenite field. This ultrafine TRIP-aided multi-phase steel showed good balance of tensile strength with total elongation, ie. 1080MPa and 26.9%. A novel in-situ neutron diffraction measurement demonstrated that the retained granular austenite transformed to martensite at a relatively large strain compared with the retained film austenite. The therein-underlying mechanism of the good mechanical properties was discussed from the view points of the morphological and thermodynamical stabilization of retained austenite.
4351
Authors: Your Yeol Lee, Jae Hyun Kwak, Jong Sang Kim, Bruno C. De Cooman
Abstract: A robust TRIP 800MPa tensile strength concept was developed for automotive applications. An optimal TRIP steel composition containing 0.3 mass-% Si and 1.0 mass-% Al was identified. Galvannealing tests revealed that this TRIP steel had an ideal surface structure prior to hot dipping. Galvannealing could be achieved successfully in normal operating conditions. The contribution gives an in depth overview of the development of this new TRIP800 concept, with a special focus on achieving the optimum properties in various CGL line configurations.
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