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Effect of Heat Input on Microstructure and Impact Toughness of Coarse‐Grained Heat‐Affected Zone in Al–Ca and Ti–Ca Killed Steels
Author(s) -
Wang Xin,
Chen Ying,
Wang Chao,
Kang Jian,
Yuan Guo,
Misra Raja Devesh Kumar,
Wang Guodong
Publication year - 2020
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.202000133
Subject(s) - acicular ferrite , materials science , nucleation , microstructure , acicular , toughness , metallurgy , grain boundary , ferrite (magnet) , composite material , heat affected zone , bainite , martensite , thermodynamics , physics
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.