Development of thin-gauge low iron loss non-oriented silicon steel

Microstructure, texture, inclusions and precipitates in Fe-2.97wt%Si non-oriented silicon steel during manufacture were investigated using Scanning Electron Microscopy (SEM), Organic Solvent Electrolysis and Electron Backscattered Diffraction(EBSD)techniques. The P10/400, P15/50 and B50 of thin-gauge non-oriented silicon steel with 0.3 mm in thickness were 13.85 W/kg, 2.38 W/kg and 1.66 T, respectively. Due to annealing of hot rolled band, the size of precipitates increased. The precipitates are mostly located at the grain boundaries in the annealed sheet, the main and average size of the grain-boundary precipitates were in the range of 30 ∼ 500 nm and 63.2 nm, respectively. The pinning force caused by 100 ∼ 300 nm particles at the grain boundaries was the largest, 70 ∼ 100 nm was second. During annealing of hot rolled band, the α*-fiber texture significantly developed and γ-fiber dropped dramatically. The γ-fiber texture and α*-fiber texture composed the main textures of annealed sheet. The texture randomization would give rise to better magnetic properties compared to the γ-fiber.

Experimental Investigations on the Effects of Rotational Speed on Temperature and Microstructure Variations in Incremental Forming of T6- Tempered and Annealed AA2219 Aerospace Alloy

This research work primarily focused on investigating the effects of changing rotational speed on the forming temperature and microstructure during incremental sheet metal forming (ISF) of AA-2219-O and AA-2219-T6 sheets. Tool rotational speed was varied in the defined range (50–3000 rpm). The tool feed rate of 3000 mm/min and step size of 0.3 mm with spiral tool path were kept fixed in the tests. The sheets were formed into pyramid shapes of 45° draw angle, with the hemispherical end forming tool of 12 mm diameter. While the sheets were forming, the temperature variation due to friction at the sheet–tool contact zone was recorded, using a non-contact laser projected infrared temperature sensor. It was observed that the temperature rising rate for the T6 sheet during ISF is higher as compared to the annealed sheet, thereby showing that the T6 tempered sheet offers higher friction than the annealed sheet. Due to this reason, the T6 tempered sheet fails to achieve the defined forming depth of 25 mm when the rotational speed exceeds 2000 rpm. The effects of rotational speed and associated rise in the temperature were examined on the microstructure, using the scanning electron microscopic (SEM). The results reveal that the density of second phase particles reduces with increasing speed reasoning to corresponding temperature rise. However, the particle size in both tempers of AA2219 received a slight change and showed a trivial response to an increase in the rotational speed.

Effect of Warm Rolling Temperature on the Microstructure and Texture of Microcarbon Dual-Phase (DP) Steel

The effect of warm rolling temperature on microstructure and texture of microcarbon dual-phase (DP) steel was investigated through scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). The results showed that with the increase of rolling temperature, the density and thickness of the deformation band first increased and then decreased. Ferrite and fine martensite were observed in the annealed sheet, and the ferrite had a much more homogeneous distribution in the sample rolled at 450 °C. During warm rolling, the ferrite developed a dominant γ-fiber and a weak α-texture. During the annealing of the rolled sheet, the intensity of the γ-fiber was increased and a weak {001}<100> texture developed in the sample rolled at room temperature. An increase in the rolling temperature generated an initial decrease and subsequent increase in the strength of the unfavorable {001}<110> texture in the annealed sheet. In addition, the strength reached a maximum at 550 °C due to an increase in the dissolved carbon in the matrix, which was result of carbide dissolution. By contrast, the intensity of the γ-fiber remained relatively higher and was deemed the weaker {001}<110> component in the annealed sheet rolled at 450 °C. Therefore, a larger texture factor (fγ-fiber/f(α-fiber+λ-fiber)) can be produced under this process.

Enhancing the Mechanical Properties and Formability of Cold Rolled Closed Annealed Sheet for Automobile Applications

Designers of high pace advanced vehicles in aerospace industries particularly vehicle manufacturing types are placing more needs at the sheet metal forming enterprise by designing components from the high strength thermal resistance alloy. The principle goal of the observation is to test the mechanical, formability parameters and Erichsen cupping values of a sample of cold rolled closed annealed sheet. The quantity of strain that a metallic sheet can tolerate just before localized failure is called limit strain. The boundaries of formability in sheet metal operations are defined regarding the primary traces via the forming limit diagram (FLD). To be useful for engineering purposes, FLD needs to be simple enough so its parameters can be evaluated without difficulty ideally by way of uniaxial tests. The consequences confirmed that the formability of steel having decreased percentage of carbon is forming lesser. It changed into pressure distribution and the grain density of the sheet verifies the formability. The best grouping of strength and ductile properties are noted for metal with the low carbon and higher forming assets.

Study on microstructure and texture of a new-type low Si high Mn non-oriented silicon steel 50W250

A new method to fabricate a high grade non-oriented silicon steel was provided, in which the significant feature is low Si high Mn. Metallographic microscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate the microstructure, texture evolution and precipitates characteristics, respectively. It is found that hot rolled sheet had a distinct stratification appearance. Fine equiaxed grains occupy the surface while subsurface and center regions were dominated by deformed microstructure and equiaxed grains. After normalizing, the microstructure of hot rolled sheet completely recrystallized. A number of shear bands were observed attributed to cold rolling. With the increase of annealing temperature or time, the average grain size of final annealed sheet increases. Annealed at 1000 °C for 7 min, annealed sheet exhibits highest and lowest fraction of {001}<100> cube texture and {112}<11-1> copper texture, respectively. The average grain size of final sheet also reaches peak, and it is 117.65 µm. In addition, the fine precipitates mainly include spherical MnS, CuS, regular hexahedral AlN, TiN and partly approximate spherical composite precipitates. The average size and distribution density are 132.10 nm and 1.62 × 1012 cm−3, respectively. Under the condition annealed at 1000 °C for 7 min, the core loss P1.5/50 is 2.461 W · Kg−1 and the magnetic induction B50 is 1.699 T.

Effect of recrystallization annealing temperature on texture and magnetic properties of 2.97% Si non-oriented silicon steel

The effect of recrystallization annealing at temperatures varying from 910 to 1060 °C on the texture and magnetic properties of cold-rolled sheets with 0.3 mm in thickness of 2.97 wt.% Si–0.59wt.% Al non-oriented silicon steel were investigated. With increasing of cold-rolled sheets annealing temperature, the average of the recrystallized grain sizes increased, because of higher temperature corresponds to a faster migration rate of grain boundaries. Increasing of grain size resulted in reducing of the hysteresis loss and core losses, as the number of grain boundary significantly reduced. However, the domain size and the eddy current loss would increase as the grain sizes continued to increase, and then affecting the core losses. The oversized microstructure (∼140 µm) in 1030 °C annealed sheet brought about an augment in P15/50 (∼2.27 W/kg) and (∼130 µm) in 1000 °C annealed sheet of P10/400 (∼12.84 W/kg). Furthermore, the textures of the final sheets were mainly made up of α*-fiber, γ-fiber and {001}<130> texture. The magnetic induction diminished with increasing of annealing temperature and this result could be attributed to the strengthening in γ-fiber (<111>//ND) and weakening in λ-fiber (<100>//ND) texture.