Characteristics of Steels in Annealing Combined with Hot-Rolling Preheating

• Published in: Journal of materials engineering and performance 2005-04, Vol.14 (2), p.179-187
• Main Authors: Khlestov, V M, McQueen, H J, Cingara, G A, Konopleva, E V
• Format: Article
• Language: English
• Subjects: Alloy steels; Alloying; Annealing; Dilatometers; Heating; High speed tool steels; Hot rolling; Steels; Transformations
• ISSN: 1059-9495; 1544-1024
• DOI: 10.1361/10599490523328

The rates of transformation and the morphologies after full annealing and industrial rolling without reheating were determined to establish the degree of similarity. Steels with 0.1-1 % C and almost nil to 17% alloying addition (M2 steel) were isothermally transformed in a dilatometer after various thermomechanical processing (TMP) sequences. For annealing, the heat treatment was performed at about 880 DGC, depending on C content, and then cooled for transfer to the dilatometer. In some cases, specimens were rolled to 50% reduction in 3 passes before cooling. The rolling schedule was simulated by preheating to 1150 DGC followed by slow cooling to 950 DGC for finish rolling as above before transfer to the dilatometer. Some specimens were directly cooled to transformation. The high preheat thoroughly homogenized the austenite (except for the M2 steel) and slowed the transformation by a factor > 10 as the alloying content rose. In all cases, the hot rolling accelerated the transformation. After the high preheat the rate and microstructure were restored to those of standard annealing for hypo-eutectoid and M2 steel.