Local texture analysis of structure non-uniformity in low carbon high-strength steel after direct quenching

The direct quenching of high-strength steels after hot rolling, which enables discard of the reheating operation, is economically efficient but necessitates a careful analysis of corresponding structural features. In particular, this treatment sometimes results in extended domains of coarse bainite decreasing the fracture toughness of steel. To reveal dependence of such effects on ausforming conditions, local textures of the parent γ-phase have been reconstructed from EBSD orientation data with allowance for the inter-phase orientation relationship. According to the obtained results, the unfavorable structural non-uniformity appears in the direct quenching due to excessive work hardening of austenite at the finish rolling stage; however, the structure and properties of steel can be improved by the reheating and subsequent quenching.

The Effect of Homogenization and Interrupted Rolling on Microstructure and Properties of Zn-Cu-Ti Rolled Sheets

Due to specific application of the Zn-Cu-Ti alloy rolled sheets as a roofing material, ready-made sheets has to meet some specific requirements of bendability at relatively low temperatures, as low as 5°C. In the current paper it was shown that susceptibility of the Zn-Cu-Ti sheets to low temperature bending, is closely related to degree of its dynamic recrystallization during rolling process. The paper discusses effect of different technological routes on the microstructure, mechanical properties and in particular the low temperature performance of Zn-Cu-Ti rolled sheets. The experimental results shows that the homogenization of Zn-Cu-Ti casted strips at the pre-rolling stage can play important role in recrystallization of the sheets during rolling. The current work is part of research on designing new technological route.

Study on Deformation Law of Drum-Shaped Blank and Collapse Defect in Rolling Process

Based on the FEM software simufact.forming, a finite element model of the radial-axial ring rolling for one ring product was constructed and the rolling process under different drum-shaped blanks were simulated in this paper, which revealed the variation of drum-shaped blank in the rolling process, analyzed the formation process and further proposed measures of eliminating collapse defect. The results show that the drum disappearing rate in initial rolling stage is greater than in later stage and it becomes increasingly difficult to disappear, which leads to collapse defect in the end. The drum-shape can be reduced by greater radial feed in initial rolling stage in the case of small drum-shape or rounding before rolling on ring rolling machine in the case of large drum-shape for avoiding collapse defect. The results provide valuable guiding significance for practical production.

Work Hardening of the Isotactic Polypropylene during Rolling

The crystallinity of the isotactic polypropylene during rolling is measured by the wide angle X-ray method. And then the influence of the crystallinity and true rolling strain on the work hardening is analyzed comprehensively. The work hardening index of the crystallinity part is 2, and the index of the amorphous part is 4. Deformation in the crystallinity part is more difficult than the amorphous part; however, the work hardening rate is smaller. The work hardening contribution of the crystalline part is higher than the amorphous part in the early rolling stage, but lower as the true strain is higher than 1.0.

FEM Simulation of the Slab Edge Rolling in Unsteady Rolling Stage

According to characteristics of adjusting width by vertical roll at a certain steel corporation, unsteady deformation of head and tail of slab during edge rolling was analyzed by FEM simulation on base of a commercial software. The effect of several process conditions on the cross-section deformation and width loss of slab were also analyzed.

Tail Deviation’s Predictive Control of the Tandem Rolling Strip Based on Manifold Learning

In the rolling process, serious deviation will cause product quality drop and rolling equipment fault. This reserch propose tail deviation’s predictive control method of the tandem rolling strip based on manifold learning. Based on real deviation data in the rolling production site,tail deviation patterns are divided according to deviation’s value. Using manifold learning method to deviation data in middle rolling stage , tail deviation pattern and scope are obtained. According to regression model between the control variable and deviation, predictive control strategy of the tandem rolling strip may be implemented. Experiment shows this method may control tail deviation in preconcerted permission range.

The Graphical Solution of Transverse Asymmetry Parameter Relationship in the Rolling Stage

Ideally rolling parameter is symmetrical relative to rolling Hcenter lineH in the rolling process. When there is transverse asymmetry incentives disturbance, Hsymmetrical stateH will be destroyed. Some Hquality problemsH will happen. The paper study transverse asymmetry characteristic of force and deformation of rolling mill and mill bar, establish parameter relationship equation of transverse asymmetry characteristic of force and deformation, establish parameter relationship figure of transverse asymmetry characteristic of force and deformation. Using this figure, we get balance control model with a view to removing strip delivery wedge.

Transfer Model of Transverse Asymmetry Characteristic in Standers during the Steady Hot Rolling Stage

During the hot rolling process, the perturbation of transverse asymmetry factor will generate strip steering, strip delivery wedge and other failure state. During the steady rolling stage, the constraint action of tension and so on can restrain strip steering. Transverse asymmetry characteristic mainly passes in the form of strip delivery wedge between the standers. Firstly this paper researches correlation of transverse asymmetry characteristic parameter toward single stander, establishes a function model to reflect transverse asymmetry result status, for instance strip delivery wedge, strip entry wedge, strip eccentric, gap wedge and other transverse asymmetry disturbance factor. Then the paper establishes transfer model of transverse asymmetry characteristic between standers, gets result status of strip delivery wedge between each ensuing standers under strip entry wedge, strip eccentric, gap wedge and other combination of disturbance. At last the paper takes working condition of actual aluminum hot rolling production line as an example, computes transfer coefficient of strip delivery wedge under several perturbation and discuss transfer discipline of transverse asymmetry characteristic between standers.

Effect of Processing Parameters on Precipitation Reactions Occurring in a Ti-Bearing IF Steel

The investigation was focused on the detailed description of precipitation/formation processes of TiN, TixSy, Ti4C2S2, TiC, and (Fe,Ti)P particles occurring in the production of thin sheets of titanium-bearing interstitial-free steels. The knowledge concerning this reactions was gained based on the thermodynamic calculation and physical simulations conducted on Gleeble 3800 thermal – mechanical simulator. The formation process of titanium carbosufide of Ti4C2S2 is the crucial reaction for the thin sheets properties. The investigation confirmed the in-situ mechanism of this phase formation, involving carbon diffusion in the TiS and TixSy sulfides’ crystal lattice. Thus, the precipitation of the substantial fraction of these sulfides is a prerequisite for further intense carbosulfide formation. Titanium sulfides are formed at the rough rolling stage of the transfer bar rolling process. The most intense precipitation of the sulfides occurs at around 1000°C. Besides the effect on the carbosulfide formation, it was found out that the sulfides substantially retard the recrystallization and grain growth in the IF steels. The most favourable Ti4C2S2 formation conditions prevail in the temperature range of approximately 950 - 920°C, which corresponds to the plate finish rolling stage. Both reactions, i.e. sulfides and carbosulfide formation, are deformationinduced processes.