Refining effect of nitrogen on M₇C₃ carbides in hypereutectic Fe–25Cr–4C–0.5Ti–0.5Nb hardface coatings

ABSTRACT

Hypereutectic Fe–Cr–C–Ti–Nb coatings with N additives were developed by surface-hardening welding (hardfacing). The experimental results showed that the primary M₇C₃ carbides were refined by the N additives in the coatings. Based on the micro-morphologies of M₇C₃ and (Ti,Nb)(C,N), the (Ti,Nb)(C,N) was present inside the primary M₇C₃ carbides, and they were tightly combined. The mismatch between the (010) crystal plane of M₇C₃ and the (110) crystal plane of (Ti,Nb)(C,N) was 6.15%, which indicated that (Ti,Nb)(C,N) was moderately effective as a heterogeneous nucleus of M₇C₃ carbides. Therefore, the preferentially precipitated (Ti,Nb)(C,N) in the Fe–Cr–C–Ti–Nb coating was the heterogeneous nucleus of the primary M₇C₃ carbides and thereby refined the primary M₇C₃ carbides .

KEYWORDS:

• M₇C₃ carbide
• (Ti,Nb)(C,N)
• Fe–Cr–C–Ti–Nb hardface coating
• refinement
• nitrogen

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China under Contract Nos. 51771167 and 51471148, the Hebei Province Basic Research Foundation of China under Contract No. 16961008D, the Science and technology projects of Longyan City (No. 2018LYF8005), the Education Research Fund of Young Teachers of Fujian Province (No. JT180532), and the Ph.D. research fund supported by Longyan University (No. LB2018020).