Textures of Non-Oriented Electrical Steel Sheets Produced by Skew Cold Rolling and Annealing

In order to investigate the effect of cold rolling deformation mode and initial texture on the final textures of non-oriented electrical steels, a special rolling technique, i.e., skew rolling, was utilized to cold reduce steels. This not only altered initial textures but also changed the rolling deformation mode from plane-strain compression (2D) to a more complicated 3D mode consisting of thickness reduction, strip elongation, strip width spread and bending. This 3D deformation induced significantly different cold-rolling textures from those observed with conventional rolling, especially for steels containing low (0.88 wt%) and medium (1.83 wt%) amounts of silicon at high skew angles (30° and 45°). The difference in cold-rolling texture was attributed to the change of initial texture and the high shear strain resulting from skew rolling. After annealing, significantly different recrystallization textures also formed, which did not show continuous <110>//RD (rolling direction) and <111>//ND (normal direction) fibers as commonly observed in conventionally rolled and annealed steels. At some skew angles (e.g., 15–30°), the desired <001>//ND texture was largely enhanced, while at other angles (e.g., 45°), this fiber was essentially unchanged. The formation mechanisms of the cold rolling and recrystallization textures were qualitatively discussed.

A simplified mathematical model for total temperature rise calculation in non-oriented silicon steel cold rolling deformation zone

In tandem cold rolling, the control of the temperature of high-grade non-oriented silicon steel is a difficult problem for its large deformation resistance and the preheating procedure before rolling. And it is complicated to calculate the total temperature rise of rolling deformation zone due to the comprehensive influence of the plastic deformation heat, the friction heat and the contact heat loss. So, to precisely calculate the total temperature rise, firstly, based on the four classical cold rolling force formulas, the initial total temperature rise calculation models are established correspondingly by theoretically analyzing the temperature rise of deformation heat, the temperature rise of friction heat and the temperature drop of contact heat loss; then, the model based on the improved Lian rolling force formula is adopted, which leads to calculated best matching the measured temperature; finally, considering the complex formula calculation of the initial model, based on the influences of different rolling parameters on the total temperature rise, a simplified model for convenient calculation is proposed by the nonlinear regression analysis of the initial model calculation results and main rolling parameters, which is convenient for the actual application by the field technicians.

On Modelling Approaches to the Influence of Mechanical Deformation on the Micromagnetic Activity in a Mild Steel

In this study an attempt is made to develop a theoretical modelling by which the influence of certain mechanical deformation factors on the micromagnetic emission behavior of a low-carbon steel can reasonably be described and estimated. This modelling consists of a simple kinetics – kinematics – aided approach of the pinning state – controlled domain wall motion by which appropriate specific parameters are introduced. In this aspect the basic notion of specific micromagnetic activity (s.m.a.) is introduced by which the energetic strength of the activity is reflected. In this way, the synergetic effect of the quantitative (count rate) and qualitative (voltage) the detected micromagnetic Barkhausen emission (MBE) is taken into consideration. Thus it is possible, theoretically, to give a prediction of the general trend of changes in the s.m.a. under the influence of the tensile elastic as well as plastic deformation. For instance, one can demonstrate that tensile elastic deformation cannot influence the s.m.a. whereas plastic one leads to an increase in this. Furthermore, one can also predict that increasing permanent (residual) plastic deformation, obtained after unloading from prior tensile loading, leads to an obvious decrease in the s.m.a. Similar decrease in the s.m.a. can also be predicted for increasing rolling deformation by means of the same modelling approach used for the permanent tensile plastic deformation. Owing to the good agreement with the experimental results and the simplicity of the proposed theoretical approaches that can be seen as a promising valuable tool for further similar studies.

Structure and Mechanical Properties of Shipbuilding Steel Obtained by Direct Laser Deposition and Cold Rolling

The study of the formation of microstructural features of low-alloy bainite-martensitic steel 09CrNi2MoCu are of particular interest in additive technologies. In this paper, we present a study of cold-rolled samples after direct laser deposition (DLD). We investigated deposited samples after cold plastic deformation with different degrees of deformation compression (50, 60 and 70%) of samples from steel 09CrNi2MoCu. The microstructure and mechanical properties of samples in the initial state and after heat treatment (HT) were analyzed and compared with the samples obtained after cold rolling. The effect on static tensile strength and impact toughness at −40 °C in the initial state and after cold rolling was investigated. The mechanical properties and characteristics of fracture in different directions were determined. Optimal modes and the degree of cold rolling deformation compression required to obtain balanced mechanical properties of samples obtained by additive method were determined. The influence of structural components and martensitic-austenitic phase on the microhardness and mechanical properties of the obtained samples was determined.

Effect of twinning and Al-Nd phase on dynamic recrystallization in rolled Mg-Al-Zn-Nd alloy at the moderate strain rate

The dynamic recrystallization of Mg-Al-Zn-Nd alloy during moderate strain rate rolling was studied using electron backscatter diffraction (EBSD) and an energy dispersive spectrometer (EDS). The results showed three kinds of twinnings produced in the alloy in the strain rate range of 4.2 s-1 ~ 7.3 s-1, including {101 ̅2} extension twinning, {101 ̅1} contraction twinning, and {101 ̅1}-{101 ̅2} double twinning. The extension twinnings decreased gradually with the increase of strain rate. The dynamic recrystallization mechanisms during hot rolling under moderate strain rate conditions mainly include grain boundary nucleation, twinning nucleation, and secondary particle assistant nucleation. The dynamic recrystallization mechanism induced by twinning is mainly {101 ̅1}-{101 ̅2} double twinnings. In addition, the strain value near the Al-Nd phase and grain boundary is higher than in grain. The Al-Nd particles in Mg-Al-Zn-Nd alloy play an auxiliary nucleation effect on dynamic recrystallization during hot rolling deformation.

Effect of Cold Rolling on the Microstructure and Mechanical Behaviors of High-Nitrogen and Low-Nickel Alloy

The effects of different cold rolling deformations on the microstructure and mechanical properties of high nitrogen and low nickel alloys were investigated. The microstructure of high nitrogen alloys with different rolling deformations were characterized by EBSD and TEM. The tensile mechanical properties of the high nitrogen alloys at room temperature were tested. The results showed that the microstructure of the cold rolled high nitrogen alloy with deformation of 0% to 70% shows a twinning process. The twin thickness of the high nitrogen alloy without deformation is micron degree. When the rolling deformation is over 50%, the average thickness of the deformation twin is 23nm. When the rolling deformation increases to 70%, the average thickness of the twin is 14nm. When the rolling deformation increases from 0% to 70%, the cold rolled high nitrogen alloy exhibits high strength (1001-2236 MPa) and excellent plasticity (5.9%-64.1%). It is beneficial to have a good combination of strength and plasticity after rolling deformation.

Mechanism of and Key Technologies for Copper Bonding in the Hot Rolling of SCR Continuous Casting and Rolling

In the process of copper alloy hot continuous rolling, the problem of copper sticking to the roller seriously affects the surface quality, performance, and service life of the copper products. Roll sticking occurs as the adhesion energy of Cu is lower than that of Fe and the Fe-Cu interface, and the severe surface deformation which forces the copper into direct contact with the roll during the process of profile rolling. Based on the copper deformation law and adhesion phenomenon in the hot continuous rolling process, a rolling deformation model and roll copper adhesion model or copper alloy hot continuous rolling were established, and their simulation was realized using finite element software. Through finite element modeling of the hot rolling deformation zone, the distribution of the temperature, contact normal stress, and exposure rate in the hot rolling deformation zone were obtained, which were consistent with the actual roll adhesion phenomenon and copper adhesion position. To address the copper sticking behavior of the rolls, the process optimization method of matching the motor speed with the elongation coefficient (the 1# and 2# motor speeds were adjusted to 1549 r/min and 1586 r/min, respectively), adjusting the roll gap to 7.9 mm, and increasing the number and pressure of roll spray nozzles were put forward, which effectively solved the problem of copper sticking to the roll, significantly improved the surface quality of the copper and the service life of the roll, and can be used in production.