Effect of cooling rate on microstructure and inclusion in non-quenched and tempered steel during horizontal directional solidification

• Published in: Journal of iron and steel research, international Vol. 26; no. 9; pp. 973 - 982
• Main Authors: Liu, Hui, Huang, Zong-ze, Yu, Da-jiang, Hu, De-lin, Zhong, Hong-gang, Zhai, Qi-jie, Fu, Jian-xun
• Format: Journal Article
• Language: English
• Published: Singapore Springer Singapore 01.09.2019
• Subjects: Applied and Technical Physics; Engineering; Machines; Manufacturing; Materials Engineering; Materials Science; Metallic Materials; Original Paper; Physical Chemistry; Processes; Horizontal directional solidification; MnS; Inclusion; Cooling rate; Dendrite
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1007/s42243-019-00282-2

In order to investigate the relationship between microstructure and MnS inclusion in non-quenched and tempered steel, and cooling rate during horizontal directional solidification, 49MnVS steel was used to conduct the experiments with a self-designed device. The mathematical effect of cooling rate on dendritic arm spacing and mean diameter of MnS particles ( d MnS ) were determined by using linear regression method. The results show that the length of dendrite from solid–liquid interface to end-solidification decreased with increasing the withdrawal velocity ( ϑ ). d MnS has a similar value in the area of the steady directional solidification; the value of d MnS was 4.1, 3.6, 3.3, 2.8 and 2.3 μm at withdrawal velocity of 50, 75, 100, 150 and 200 μm/s, respectively. d MnS increased with reducing ϑ or R C (interface cooling rate). MnS precipitated in the gaps between dendrites and was influenced by secondary dendritic arm spacing. Besides, a new concept of the ‘Precipitation Unit Space’ (PUS) was proposed and the relationships between d MnS , V PUS (volume of PUS) and R C were obtained.