Materials Science Forum Vols. 495-497

Abstract: A micromechanical model was used to simulate the mechanical behaviour, the transformation kinetic and the texture evolutions of a 304 stainless steel, deformed by tensile tests at T=–60°C. When the transformation strain is calculated with the phenomenological theory, the model does not very well predict the observed transformation rate and the texture evolution of the main γ grain orientations. XRD and EBSD analyses show that the martensitic transformation of γ phase into α’ martensite involves the intermediate ε phase. From these observations, new simulations were performed in which only the γ→ε transformation strain is considered in competition with classical plasticity of austenite. The α’ variants were calculated in a second step, from the ε variants selected in the micromechanical model. Among the 6 potential α’ variants able to nucleate from the same ε variant, the best oriented ones, with respect to the applied stress were selected. Under these conditions, the numerical simulations reproduce the experimental results in a more satisfying way.

Abstract: The aim of this work is to investigate the relationship between the deformation microstructure and texture in cold rolled Interstitial Free (IF) steel sheets. In the present research, the cold rolled IF steel sheets with 10%-50% reductions are used to observe the characteristic microstructure and individual orientations by transmission electron microscopy (TEM) and SAED patterns. The experimental results on inter-granular strain homogeneity and dislocation wall formation are given in details in this paper. The results are explained by the analysis of crystallographic gliding and are helpful to improve the prediction of cold rolling textures.

Abstract: An experimental setup was designed to study the recrystallization kinetics of Interstitial Free (IF) steel in this work. The 80% cold rolled IF steel foils are heated rapidly to 680°C, 730°C and 780°C by a salt bath. The recrystallization kinetic curves were obtained by the quantitative analysis of texture components, microstructures and EBSP (electron back-scattering patterns) measurements. With the help of EBSD, the orientations of the recrystallization nuclei are determined. The growth rule of the recrystallization nuclei was analyzed statistically. The effect of nucleus orientation on the formation of the recrystallization texture was investigated.

Abstract: The microstructure of Ti+P IF steel were studied after warm rolling, cold rolling and recrystallization using X-Ray, TEM and SEM. The results show that the characteristics of warm rolled sheet are the same as that of the cold rolled, but the texture displays different characteristics in the subsequent cold rolling and recrystallization because of the numerous second-phase particles. In this work, a Ti+P IF steel sheet with high strength and plastic strain ratio was obtained.

Abstract: Fe-3.10%Si thin strips were prepared from commercial grain oriented silicon steel sheet by cold rolling with different speed ratios and annealed at 1123K in vacuum, the cold rolling and recrystallization textures were analyzed. Cold rolling texture consists mainly of {111}<112>, {554}<225> and {332}<113> components, while their orientation densities vary with speed ratio and layer through strip thickness. Recrystallization texture development depends on speed ratio obviously, and the peak orientation density deviates from {110}<001> towards {210}<001> with the increase in speed ratio.

Abstract: Fe-3.10%Si thin strips were prepared by symmetric and asymmetric cold rolling from commercial grain oriented silicon steel sheets, then annealed with and without a magnetic field. Magnetic field of 12T was applied along the rolling direction. Magnetic annealing does not essentially change the texture development that recrystallization texture consists mainly of η fiber (RD//<001>), and the strongest component tends to transform from Goss ({110}<001>) to {210}<001> with the increase in speed ratio and annealing temperature. But magnetic annealing promotes Goss component in the strips rolled with small speed ratios, while decreases {210 <001> component in those rolled with large speed ratios. Possible effect mechanism of magnetic annealing was discussed.

Abstract: In this research, surface texture changes of carbon steel AISI 1045 and stainless steel AISI 304 under simultaneous wear and corrosion were investigated. A solution of 3.5 % wt. NaCl was used as the corrosion agent and a pin-on-disk tribometer was employed to perform wear and corrosion wear tests.Texture investigations of the worn samples have shown texture changes after wear and corrosion-wear tests. In worn carbon steel samples after dry wear test, {011}<100> and {111} fiber texture components were developed in initially random oriented samples, whereas under corrosive-wear conditions, {111}<011> texture and {001}<110> texture were developed. In the stainless steel samples, {112}<110> texture component was observed under both dry and corrosive wear conditions, in the samples that had random grain orientations before corrosion and corrosion-wear tests.

Abstract: The ferrite to austenite phase transformation in microalloyed steel was studied, with a special focus on the orientation relationship between prior ferrite and subsequent austenite. Also the role of growth selection and preferred nucleation was investigated in this context. Their effects were examined at partial phase transformation.

Abstract: The present study had one broad objective – to systematically characterize effects of overall grain boundary nature on localized corrosion, intergranular corrosion (IGC) and stress corrosion cracking (IGSCC), of type 304 (UNS S 30400) austenitic stainless steel. Various combinations of cold rolling and solution annealing, were applied to alter relative the relative concentrations of ‘special’ or low CSL boundaries and to relate them with the local corrosion resistance, IGC and IGSCC, after respective sensitization treatments. It has been shown that both extreme high and low concentration of random (or high energy) boundaries can provide an effective means of control for localized corrosion, degree of sensitization (DOS), IGC and IGSCC, - the improvement in localized corrosion resistance at extreme grain boundary randomization being more effective.

Abstract: The improvement of the mechanical behaviour of high performance steels brings about a renewed interest for the work hardening rate resulting from deformation-induced martensitic transformation or mechanical twinning. Even if these mechanisms are known for quite a long time, the deformation – transformation interactions that they induce is not yet fully characterised and understood. This study aims at characterising the microstructure evolution of a Fe-Mn steel grade during straining thanks to TEM and high resolution OIM. Particular patterns of austenite – e and a’ martensite are found.