Showing papers on "TRIP steel published in 2000"
TL;DR: In this article, a new strain-induced martensitic transformation kinetics model and constitutive equation of TRIP steels are proposed by considering the dependence of the austenitic grain size.
100 citations
TL;DR: In this paper, the mechanical properties of eight different steels, representing a wide range of steels for automotive application, are determined by accomplishing high speed tensile tests using flat sheet specimens.
Abstract: The mechanical properties of eight different steels, representing the wide range of steels for automotive application, are determined by accomplishing high speed tensile tests using flat sheet specimens. The steels chosen for investigations are deep drawing grade DC04, high strength steel ZStE340, three dual phase steels with strengths of 600, 800 and 1000 MPa, a TRIP steel and two austenitic stainless steels 1.4301 and 1.4318. Tests are carried out at five different strain rates within the range of 5.10 -3 and 200 s -1 , all at room temperature. The results show different strain rate sensitivities according to the different grades of steel. The TRIP steel and both stainless steels show a great potential for energy consumption, when tested at high strain rates.
87 citations
TL;DR: In this paper, a new family of high-strength low and medium-alloyed bainitic steels with ultra-low carbon content and copper or micro alloy additions has been developed.
31 citations
Journal Article•
TL;DR: In this article, Al-alloyed transformation induced plasticity (TRIP) steels have improved formability and are better suited to galvanizing than conventional C-Mn-Si TRIP steel.
Abstract: Researchers at Ghent University and OCAS NV in Belgium believe Al-alloyed transformation induced plasticity (TRIP) steels have improved formability and are better suited to galvanizing than conventional C-Mn-Si TRIP steel.
11 citations
TL;DR: In this article, the ageing behavior of TRIP steels and the effect of controlled ageing of the complex microstructure by paint baking on the mechanical properties were investigated, and a BH mechanism was proposed to evaluate their actual in-service properties.
Abstract: Cold rolled, intercritically annealed TRIP steels will very likely be used as electrogalvanized sheet steel for passenger safety-related automotive body parts. This implies that their properties during and after manufacturing, i.e. in the deformed and paint-baked state, must be known to evaluate their actual in-service properties. The ageing behaviour of electrogalvanized TRIP steels and the effect of controlled ageing of the complex microstructure by paint baking on the mechanical properties was therefore investigated. Electroplating tests showed that the H uptake during pretreatment and electrogalvanization is limited and that the paintability of the electroplated sheet steel is unaffected even after deformation induced transformation of the austenite. In addition, a strong bake hardening effect was found in the case of the CMnAISi TRIP steel. Internal friction measurements indicated that a damping peak for interstitial C could be obtained but that the free C content was less than 1 ppm prior to paint baking. A BH mechanism for TRIP steels is proposed.
7 citations
TL;DR: In this article, the development of a model to predict the isothermal austenite grain growth during soaking of a low carbon Si-Mn TRIP steel is described, and a procedure is delineated to calculate the values of the different constants of the equation starting with the real three-dimensional austenites grain size.
Abstract: The development of a model to predict the isothermal austenite grain growth during soaking of a low carbon Si-Mn TRIP steel is described. After reviewing the existing models for isothermal grain growth, a general model d n =d 0 n +K 1 t exp(K 2 / T) was selected and a procedure was delineated to calculate the values of the different constants of the equation starting with the real three-dimensional austenite grain size. This paper also deals with an improved etching technique to reveal the austenite grain boundaries.
6 citations
TL;DR: In this paper, the isothermal grain growth of a low carbon, silicon-manganese bearing TRIP-steel has been studied using the theory described in the preliminary publication, using the measurement of the mean linear intercept distance, which has been transformed into the real mean austenite grain size.
Abstract: Using the theory described in the preliminary publication, the isothermal grain growth of a low carbon, silicon-manganese bearing TRIP-steel has been studied. The austenitic grain size was established through the measurement of the mean linear intercept distance, which has been transformed into the real mean austenite grain size. A general model of the form d n =d 0 n +K 1 t exp(K 2 / T) was used and the coefficients n, Kl and K2 have been statistically determined. It has been demonstrated that for low annealing temperatures the value of n is situated around 6, whereas at high temperatures n rapidly drops and adopts a value of 2. This behaviour was related to the dissolution of the precipitates present in the austenitic matrix during the soaking treatments. The model delivers very good predictions for soaking temperatures up to 1200 °C. For higher temperatures, the deviations between the predicted grain size and the really measured one are higher.
6 citations
TL;DR: The effect of shape and volume fraction of retained austenite on the uniaxial behavior of transformation induced plasticity (TRIP) steels was studied by using the numerical and experimental methods as mentioned in this paper.
Abstract: The effect of shape and volume fraction of retained austenite on the uniaxial behavior of transformation induced plasticity(TRIP) steels was studied by using the numerical and experimental methods. 0.16%C-1.4%Si-1.4%Mn TRIP steels were intercritically annealed at 800 o C and 840 o C, and isothermally transformed at 450 o C (Banite Transformation) during 1, 5 and 10 min. As the bainite isothermal transformation time increased, the volume fraction of retained austenite, tensile stress and total elongation decreased, and 0.2% yield stress increased. Finite element method calculations were carried out by using ABAQUS user subroutine UMAT based on the finite deformation theory and self-consistent method. Numerical results were in good agreement with experimental data.
2 citations
TL;DR: In this article, the authors defined the fraction tensor, which components are the line fractions of the martensite, in order to evaluate the orientation of the Martensite and measured it from the micrographs of TRIP steel previously obtained.
Abstract: There are various kinds of smart materials with a martensitic transformation, such as the shape memory alloy and the tranformation-induced plasticity (TRIP) steel, etc.; their applications to actuators, structural materials, etc., are investigated. The martensitic particles orient against the loading axis in the micro region so that it may be possible to improve their mechanical properties by the control of their orientation like the composite materials. Here, the fraction tensor, which components are the line fractions of the martensite, was defined in order to evaluate the orientation of the martensite. The validity of the the fraction tensor for investigating their orientations is discussed by a comparison of the fabric tensor. Then, the fraction tensors were measured from the micrographs of TRIP steel previously obtained. Furthermore, the orientation of the martensite in the TRIP steel was discussed by a polar diagram of the line fraction and the fraction tensor. Finally, the dependence of the fraction tensor on plastic strain, temperature and stress state was discussed.
1 citations