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United States Patent | 4,840,051 |
Boratto , et al. | June 20, 1989 |
A series of thermomechanical workings such as temperature-controlled torsional strains are applied to a specimen of steel at strain and temperature levels and interpass times selected to simulate rolling mill conditions. The measured stress values are compared with the temperatures of the steel during the working periods during which the respective values were obtained. Thermomechanical working schedules are repeated at selected varying starting and terminating temperatures thereby to obtain a series of possible rolling schedules. These simulations are selected so that a varying number of reduction passes in the sequence occur at steel temperatures below temperature A.sub.r3. The value of a selected parameter of the worked steel, e.g. yield strength, is measured at ambient temperature. From the rolling mill analogue of possible rolling schedule simulations, an optimized rolling schedule is selected which will predictably impart to the steel a value of the selected parameter falling within a predetermined range. Linear regression analysis is applied to empirically obtained rolling mill data to derive one or more linear relationships between a selected property (e.g. yield strength) of the steel and rolling mill parameters thereby to permit selection of an optimum rolling schedule suitable to obtain a preselected value of the selected property of the steel.
Inventors: | Boratto; Francisco (Westmount, CA), Yue; Stephen (Montreal, CA), Jonas; John J. (Westmount, CA) |
Assignee: |
Ipsco Inc.
(CA)
|
Appl. No.: | 07/055,945 |
Filed: | June 1, 1987 |
Current U.S. Class: | 70/11 ; 374/134; 374/48; 700/149; 72/229; 72/234; 72/366.2; 72/8.5; 73/866 |
Current International Class: | B21B 1/30 (20060101); B21B 1/32 (20060101); B21B 1/26 (20060101); B21B 001/00 () |
Field of Search: | 73/866 374/45-52,134 364/472 72/199,229,365,366,234,11,13,12 |
T Tanaka, N. Tabata, T. Hatomura and C. Shiga: `Three Stages of the Controlled Rollin Process`, Microalloying '75, Washington, DC, 1975, Union Carbide, New York, 1977, pp. 107-119. . S. Benrong, Z. Peixiang and Z. Ronglin: `A Study of Controlled Rolling Technology in the (.gamma.+.alpha.) Two-Phase Region`, HSLA Steels, Metallurgy and Applications, Beijing, China, 1985, ASM International, 1986, pp. 181-188. . P. D. Hodgson, J. A. Szalla and P. J. Cambell: `Modelling of Thermomechanical and Metallurigical Processes in Plate Rolling`, 4th. International Steel Rolling Conference, Deauville, France, Jun. 1987, 1 paper C-8. . P. Choquet, A. Le Bon and Ch. Perdrix: `Mathematical Model for Prediction of Austenite and Ferrite Microstructures in Hot Rolling Processes`, Strength of Metals and Alloys (ICSMA 7), 1985, Pergamon, New York, 1985, pp. 1025-1030. . F. Boratto, S. Yue, J. J. Jonas and T. H. Lawrence: `Production of High Strength Nb Microalloyed Steel Sheet in a Steckel Mill`, 4th. International Steel Rolling Conference, Deauville, France, Jun. 1987, 2, paper F-20.. |