Microstructure and phase elemental distribution in high-boron multi-component cast irons

• Published in: International journal of minerals, metallurgy and materials Vol. 29; no. 1; pp. 78 - 87
• Main Authors: Chabak, Yu. G., Shimizu, K., Efremenko, V. G., Golinskyi, M. A., Kusumoto, K., Zurnadzhy, V. I., Efremenko, A. V.
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 2022; Springer Nature B.V; Physics Department,Pryazovskyi State Technical University,Mariupol,87555,Ukraine%Mechanical Engineering Research Unit,College of Design and Manufacturing Technology,Muroran Institute of Technology,Muroran-city,050-8585,Japan
• Subjects: Alloying elements; Austenite; Boron; Cast iron; Ceramics; Characterization and Evaluation of Materials; Chemical composition; Chemistry and Materials Science; Composites; Corrosion and Coatings; Eutectic temperature; Ferrite; Glass; Iron constituents; Materials Science; Metallic Materials; Metallurgical constituents; Microhardness; Morphology; Natural Materials; Pearlite; Phase distribution; Precipitates; Surfaces and Interfaces; Thin Films; Tribology; Wear resistance; X-ray spectroscopy; eutectic; multi-component cast iron; boron; carboboride; carbide
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-020-2135-8

The novel cast irons of chemical composition (wt%) 0.7C—5W—5Mo—5V—10Cr—2.5Ti were invented with the additions of 1.6wt% B and 2.7wt% B. The aim of this work was to study the effect of boron on the structural state of the alloys and phase elemental distribution with respect to the formation of wear-resistant structural constituents. It was found that the alloy containing 1.6wt% B was composed of three eutectics: (a) “M 2 (C,B) 5 +ferrite” having a “Chinese Script” morphology (89.8vol%), (b) “M 7 (C,B) 3 +Austenite” having a “Rosette” morphology, and (c) “M 3 C+Austenite” having a “Ledeburite”-shaped morphology (2.7vol%). With 2.7wt% of boron content, the bulk hardness increased from HRC 31 to HRC 38.5. The primary carboborides M 2 (C,B) 5 with average microhardness of HV 2797 appeared in the structure with a volume fraction of 17.6vol%. The volume fraction of eutectics (a) and (b, c) decreased to 71.2vol% and 3.9vol%, respectively. The matrix was “ferrite/austenite” for 1.6wt% B and “ferrite/pearlite” for 2.7wt% B. Both cast irons contained compact precipitates of carbide (Ti,M)C and carboboride (Ti,M)(C,B) with a volume fraction of 7.3%–7.5%. Based on the energy-dispersive X-ray spectroscopy, the elemental phase distributions and the appropriate phase formulas are presented in this work.