Effect of Heat Input on Microstructure and Impact Toughness of Coarse‐Grained Heat‐Affected Zone in Al–Ca and Ti–Ca Killed Steels. Issue 9 (16th April 2020)

• Record Type: Journal Article
• Authors: Wang, Xin; Chen, Ying; Wang, Chao; Kang, Jian; Yuan, Guo; Misra, Raja Devesh Kumar; Wang, Guodong
• Is Part Of: Steel research international. Volume 91:Issue 9(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-04-16
• Subjects: acicular ferrites -- coarse-grained heat-affected zone -- oxide particles -- toughness -- welding heat inputs; Steel -- Periodicals; Steel -- Metallurgy -- Periodicals; 669.142
• DOI: 10.1002/srin.202000133
• Languages: English
• ISSNs: 1611-3683

Abstract

Abstract : The microstructural evolution and toughness properties of simulated coarse‐grained heat‐affected zone (CGHAZ) in Ti–Ca killed steel with different heat input are studied and compared with Al–Ca killed steel. It is found that the impact toughness of CGHAZ in Ti–Ca killed steel with heat inputs of 50, 100, and 200 kJ cm −1 is ≈129, ≈105, and ≈44 J, respectively. However, the toughness of Al–Ca killed steel decreases from ≈28 to ≈23 J and then to ≈18 J. In Ti–Ca killed steel, Ti–Ca–Al–Mn–S oxides with appropriate size of ≈0.3–2 μm effectively promote the nucleation of acicular ferrite (AF). In addition, the high‐density number of ≈1329 inclusions mm −2 is one of the most important reasons for the formation of AF. However, dominant Al–Ca–Mn–S oxides in Al–Ca killed steel cannot effectively promote the nucleation of AF and mainly act as a potential propagation site of impact crack. In Ti–Ca killed steel, predominantly interlocked AF with high‐angle grain boundaries and high‐density of dislocations remarkably improves the toughness of CGHAZ. Abstract : From 50 to 200 kJ cm −1, the impact toughness in simulated coarse‐grained heat‐affected zone of Ti–Ca killed steel is correspondingly higher than that of Al–Ca killed steel. At 50 kJ cm −1, the toughness of Ti–Ca killed steel is ≈101 J higher than Al–Ca killed steel, which is due to acicular ferrite nucleation induced by Ti–Ca oxide inclusions.