Micro Characterization of Hot-Rolled Plate of Nb-Bearing Grain-Oriented Silicon Steel

In this study, niobium was added into grain-oriented silicon steels, four Nb-bearing hot-rolled bands with Nb content range from 0–0.025 wt% were prepared and a detailed study of the micro characterization (microstructure, texture and precipitates) of hot-rolled bands was carried out by various analysis methods, such as EBSD and TEM. The results indicate that the precipitates in Nb-free steel are MnS and AlN; however, in the Nb-bearing steel they are MnS, AlN and Nb(C, N). The precipitates are finer and more dispersed in Nb-bearing steel, and a stronger pining force was obtained, which contributes to the finer microstructure and less recrystallization fractions of the hot-rolled bands. A larger volume fraction and stronger intensity of Goss texture is presented in steel with 0.025 wt% Nb due to the effective inhibiting effect. However, it has little effect on the changes of microstructure and texture when the Nb content is more than 0.009 wt%.

Effect of the Initial Texture, Recrystallization and Re-Dissolution Process on the Evolution of Texture during Solution Treatment of the 7A65 Hot Rolled Plate

The evolution of textures, the degree of recrystallization and the mechanical properties of 7A65 hot rolled plates during re-dissolution were studied with different thicknesses (25 mm, 65 mm, 120 mm) and different degrees of deformation. It was found that different plates exhibited different trends of re-dissolution because the degrees of deformation increased and the degrees of recrystallization were different during the solution treatment. With the increase of deformation and static recrystallization degrees, texture types changed from Cube, R-Cube to Brass, R, Cube and Copper during the re-dissolution process. The value of the Schmid factor (µ(-)) was calculated and the value along the rolling direction was significantly larger than along the transverse direction, which led to a lower yield strength along the rolling direction. In terms of the average contribution of the yield strength, the strengthening of the grain boundary including LAGBs (low-angle grain boundaries) was found to play a more significant role than the effect of solid atoms and dislocation densities. Therefore, the 25 mm plate exhibits the best mechanical properties, with a yield strength of 565.7 MPa along the rolling direction.

Variation in Deformation Behaviors Along the Transverse Direction During the Warm Rolling of a 1480-mm-Wide AZ31B Plate

A decrease in the weight of aerospace vehicles, large ships, weapons, and high-speed trains will increase the demand for wide-width magnesium alloy plates and their composite parts to replace steel and plastic. An investigation was conducted to study the variation in deformation behaviors along the transverse direction during the warm rolling of a 1480-mm-wide AZ31B plate. A uniaxial thermal compression test with a 59 % reduction was performed at different positions on a 13.7-mm-thick rolled plate along the width direction at a temperature of 220 °C and 270 °C and strain rate of 15 s−1. At the same time, the 13.7-mm-thick plate was rolled in a single pass to 5.6 mm on a mill with a 1725-mm-wide roll to confirm the thermal deformation behavior and the dynamic recrystallization (DRX). The results show that the main texture type does not change and the grain size does not have a clear deflection when the magnesium alloy plate reaches a certain value under rolling accumulative reduction. The grain size of a 13.7-mm-thick plate increases with a decrease in the distance to the center layer in the thickness direction. In the width direction, the edge (R6) first decreases and then increases toward the symmetric plane (R1). The critical stress required for dynamic recrystallization in the transition zone R3 of the rolled plate width is minimum, and the average grain size is minimum owing to the relatively complete recrystallization.

Influence of Anisotropy Properties of as-Rolled CMn Plate on Welding Induced Distortion

Welding induced distortion remain persistent problems leading to the inferior on Product Quality. The study is to investigate on welding induced angular distortion due to effect of anisotropy properties of the As-rolled C-Mn plate. The outcome could enhance the minimum distortion while cutting the raw material on rolling direction for fabrication process. The Anisotropy properties of the base metal were analyzed with along and transverse to rolling direction through microstructure examination, hardness measurement and mechanical properties. Microstructure contains coarse grains of pearlite and ferrite in transverse to rolling, whereas fine grains along the rolling. Hardness was 80 and 84 HRB along and transverse to rolling respectively. A weld bead was laid on the plate’s substrate with along and transverse to the rolling and angular deflections were measured with a dial gauge indicator. Finite element analysis (FEA) was carried out to evaluate the angular deflection on both the rolling. From the experimental results, the anisotropy properties of the as-rolled plate had influenced on angular deflection and indicating with good agreement with FEA.

Analysis of the influence of hot rolled plate steel treatment using temper and quench-temper method on vickers hardness number enhancement

This paper wants to know the effect of bending radius on the distribution of hardness, grain distribution and microstructure on the surface area of tensile stress and compressive stress after bending, quenching and tempering. Material testing helps determine and analyze material quality. The research was conducted on the bending of Hot Rolled Plate Steel material with a radius of 50 mm, 55 mm, 60 mm, 65 mm and 70 mm with a measurement distance of 1 mm, 2 mm and 3 mm, the highest value was obtained at a radius of 55 mm with a measurement distance of 1 mm. After getting the quench-temper treatment with a holding time of 30 minutes, the value of 498 HV was obtained at a radius of 70 mm with a measurement distance of 2 mm. Hardness test was performed using the austenite temperature of 900 °С, microstructure test results obtained finer grains in the compression area r=2.173 µm and in the tensile area r=2.34 µm. This observation aims to determine the microstructure of the material undergoing a heat treatment process at a temperature of 900 °С with a holding time of 30 minutes using water cooling media. The results of the observation of the microstructure of the test specimens before the quench-temper process showed that the structure of ferrite was more abundant than perlite, but after the quench-tempering process the results showed that there was more perlite than ferrite due to the presence of austenite. The treatment on the transformation of the Ar3 line causes the hardness to change the shape of the martensite microstructure into steel while the thickness of the carburizing layer increases with the increase in the carbonization temperature on the surface of the quenched specimen, resulting in the formation of martensite and residual austenite causing the coating to become hard.

Evolution of Microstructure and Mechanical Properties of Mg-6Al Alloy Processed by Differential Speed Rolling upon Post-Annealing Treatment

Magnesium-6 wt.% aluminum (Mg-6Al) alloy plates with a 6-millimeter thickness were processed from an initial 12-millimeter thickness by differential speed rolling (DSR), with a 0.76-millimeter thickness reduction per pass using a speed ratio of 2, preheating temperature of 315 °C, and roll temperature of 265 °C. The effects of annealing temperature of 250, 275, and 300 °C with a corresponding holding time of 15 min on the microstructure, texture, and mechanical properties were investigated. Key results show that dynamic recrystallization (DRX) occurred during the roll processing, resulting in a greatly reduced grain size. In addition, the basal pole of the as-rolled plate was inclined to the rolling direction (RD) by ~20°, due to the shear strain introduced during DSR. Subsequent annealing caused grain growth, eliminated the basal pole inclination towards the RD, and slightly increased the pole intensity. Compared with the as-rolled plate, the average of the ultimate tensile strength (UTS) and the yield strength (YS) of the annealed plates decreased, while the average elongation at fracture (εf) increased. With the annealing temperature of 275 °C, the plate achieved a good combination of mechanical properties with UTS, YS, and εf being 292.1 MPa, 185.0 MPa, and 24.9%, respectively. These results suggest that post-roll annealing is an effective way to improve the mechanical response of this Mg alloy processed by DSR.

Nanoscale phase separations in as-fabricated thick super duplex stainless steels

Nanoscale phase separations, and effects of these, were studied for thick super duplex stainless steel products by atom probe tomography and mechanical testing. Although nanoscale phase separations typically occur during long-time service at intermediate temperatures (300–500° C, our results show that slowly cooled products start to develop Fe and Cr separation and/or precipitation of Cu-rich particles already during fabrication. Copper significantly slowed down the kinetics at the expense of Cu-rich particle precipitation, where the high-copper material subjected to hot isostatic pressing (HIP), with Δt500–400 of 160 s and the low-copper hot-rolled plate with Δt500–400 of 2 s had the same level of Fe and Cr separation. The phase separations resulted in lower toughness and higher hardness of the HIP material than for hot-rolled plate. Therefore, both local cooling rate dependent and alloy composition governed variations of phase separations can be expected in as-fabricated condition.

Correlation among Microstructure, Texture, and Properties along the Thickness Direction in As-Hot-Rolled and As-Solution-Quenched Al7055 Thick Plates

Both microstructure inhomogeneity and mechanical property diversity along the thickness direction in rolled thick aluminum plates have been considered to have a remarkable impact on the performance and properties of the products made from the plates. In this study, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) characterizations of microstructure and texture types along the thickness directions of Al7055 thick plate specimens prepared using two conditions, hot-rolling and solution-quenching, were performed. To examine the mechanical properties, uniaxial tensile tests were also carried out on specimens machined from both types of thick plates, using a layered strategy along the thickness direction. The results indicate that both the microstructure and mechanical properties are inhomogeneous under the two conditions. Furthermore, it is evident that there is a hereditary relationship between the mechanical properties of the two plates—areas with higher yield strength in the as-hot-rolled plate correspond to areas with the higher yield strength in the as-solution-quenched plate