Quantitative analysis of microstructure and impact toughness in the simulated coarse-grained heat-affected zone of Cu-bearing steels

ABSTRACT

Because of 0.32% Cu addition, the inclusion is modified from Al-Ti oxide covered with layer of MnS in Cu-free steel to Al-Ti oxide with shell of (Mn,Cu)S in Cu-bearing steel. The quantitative result reveals that the frequency of inclusion effectively for acicular ferrite nucleation, fraction of acicular ferrite and high angle grain boundary in the simulated coarse-grained heat-affected zone (CGHAZ) of Cu-bearing steel are higher than that of Cu-free steel, respectively. Therefore, the high density of acicular ferrite microstructures in CGHAZ of Cu-bearing steel with smaller crystallographic grain size has superior impact toughness than that in Cu-free steel.

KEYWORDS:

• CGHAZ
• Cu
• inclusion
• acicular ferrite
• impact toughness

Additional information

Funding

The authors gratefully acknowledge the support from China Postdoctoral Science Foundation [grant number 2014M550414] and National Natural Science Foundation of China [grant number 51401152], [grant number 51501134].