Hot Rolling Operation Research Articles

Results of hot direct rolling operation

Kwangyang No.2 continuous caster, which is designed for Hot Direct Rolling (HDR) process, has started its operation in November 1990.

Modelling microstructural development during hot rolling

AbstractThe reasons for computer modelling the pass-by-pass development of microstructure during industrial hot rolling operations are briefly considered, and the principles of modelling are outlined. Quantitative relationships between the kinetics of static recrystallisation, recrystallised grain size and the variables of a rolling pass are compared for C–Mn steel and for Al–1 Mg/commercial Al, and the consequences for multipass rolling are discussed. For the steel, description of austenite grain structure in terms of grain size and residual strain leads to model predictions in good agreement with observation, and the value of modelling is well established. For aluminium, the same approach is shown to lead to anomalies, indicating that a more sophisticated description of microstructure is required. The possible roles of intermetallic particles are discussed.MST/1300

Computer modelling of hot-working processes

AbstractIn this paper, the development of process modelling within the Department of Metallurgy at The University of Sheffield is traced. This was initially concerned with predicting temperature distributions generated during hot-extrusion and hot-rolling operations, but the principles of finite-difference modelling have also been applied to upset forging and compression testing. The modelling of microstructural evolution during multipass working operations from the basis of laboratory test data was developed separately. These two aspects have been combined, and the effects of microstructure, temperature, and other engineering variables on flow stress have been incorporated to produce a model of hot rolling which predicts microstructural changes at each stage of the process and takes into account their effect on rolling-load and power requirements.MST/168

Recrystallization and texture development in dispersion-strengthened nickel-base superalloys

The recrystallization heat treating cycle is shown to be a critical factor in determining the final texture of an extruded and hot-rolled yttria-dispersed superalloy. It appears that recrystallization in such systems is not a dynamic process,i.e., no recrystallization occurs during hot-rolling operations. Further, pole figures obtained from fully recrystallized specimens demonstrate that the temperature from which the recrystallization treatment is started determines the final crystallographic orientation of the system. (110){001} and (110){110} texture will be developed only if the cycle is started within a specific temperature range; initial temperatures either too low or too high promote other orientations.

Health hazards associated with rolling normal and enriched uranium-evaluation and control.

Industrial health surveys have been made over a period of 5 years during rolling operations with normal uranium at LASL and at two off-site plants. The results indicated that personnel participating in this work were not exposed to above-tolerance levels of external or internal radiation hazards. The external radiation hazards were evaluated by means of personnel film badges. The internal hazards from alpha active particles were measured by means of air and urine samples. The exposure at LASL during normal uranium rolling (with adequate ventilation) never exceeded 10% of tolerance. During hot rolling (primary) operations at an off-site plant, with inadequate or no ventilation, personnel were exposed to levels of air-borne contamination above daily tolerance levels for short periods of time. During warm rolling (secondary) operations with normal uranium at a second off-site plant, exposures were less than 10% of daily tolerance levels. Industrial health surveys have been made during enriched uranium rolling operations at LASL. These rolling operations were performed in a workroom with ventilation designed for normal uranium operations. Results of air sampling indicate personnel were exposed to air concentrations above tolerance for short periods of time. Results of urine analysis showed the average exposures never exceeded 20%more » of tolerance. Hot rolllng from salt baths presents the greatest hazards. Hazards during warm rolling from oil baths are minimal. Recommendations are given for the control of health hazards.« less

OILS FOR METAL ROLLING

OF the whole range of metal rolling operations, almost the only section in which rolling oils are normally employed is in the cold rolling of flat material in plain cylindrical rolls. The metal for cold rolling has usually first been hot rolled in plain cylindrical rolls, but only in a few cases are rolling oils used in the hot rolling operation. These exceptions are referred to when considering the particular metals.