Refinement mechanism and optimization for compact strip production process

Abstract

To avoid the fracture of cold-rolled sheets, this study investigated the refinement mechanism for the compact strip production process and proposed an optimised method. The primary austenite grain size was 50–475 µm, and the grain size of the hot-rolled strips was 3.6–4.8 µm. The Gleeble-3500 simulator was applied to simulate the hot rolling process. Grain refinement was realised through dynamic recrystallization and the supply of more nucleation sites for transformation by sub-structures. Increasing the coiling temperature from 620 to 730 °C increased the ferrite fraction from 3.95 to 24.16%. The adjacent cementite distance changed from 0.33 to 0.84 µm, resulting in decreased yield and tensile strengths and increased elongation. Thus, the fracture of cold-rolled sheets was avoided.

KEYWORDS:

• S50C steel
• CSP process
• grain size
• phase transformation
• mechanical properties

Acknowledgements

The authors would like to thank the National Natural Science Foundation of China No. 62071034, and the management of Jiuquan Iron & Steel (Group) Co., Ltd., China, for giving permission to publish this work. X. Wei is grateful for the financial support of DFG (German Research Foundation), Project-ID: 169148856-SFB 920, subproject C01 at the Technical University Bergakademie Freiberg.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China: [Grant Number No.: 62071034].