MICROSTRUCTURE AND PROPERTIES OF HIGH CHROMIUM WHITE CAST IRONS ALLOYED WITH BORON
DOI:
https://doi.org/10.17770/etr2021vol3.6656Keywords:
high chromium white cast iron, boron, microhardness, hardness, impact toughness, bending strengthAbstract
The microstructure and mechanical properties of high chromium white cast iron with composition: 2,6÷3,4% C; 0,9÷1,1% Si; 0,8÷1,1% Mn; 1,0÷1,3% Mo; 12,3÷13,4% Cr, additionally doped with boron in an amount of 0,18% to 1,25% is investigated. The microstructure of six compositions of white cast irons is studied by means of an optical metallographic analysis - one without boron, and the others contain 0,18%; 0,23%; 0,59%; 0,96% and 1,25% boron.
A test is performed to determine: hardness by the Rockwell method; microhardness; bending strength and impact toughness. It was found that at a boron content of 0,18%; 0,23% and 0,59%, the structure of white cast irons is subeutectic, with impact toughness in the range of 1,80÷1,52 J/cm2; with a boron content of 0,96%, the structure of white cast iron is close to the eutectic, with impact toughness 0,98 J/cm2 ; at a boron content of 1,25% the structure of white cast iron is supereutectic and the impact toughness decreases to 0,68 J/cm2.
With a change in the boron content from 0,8% to 1,25%, the amount of carbide phase in the structure of white cast iron increases, which leads to an increase in hardness from 53 to 59 HRC. The highest bending strength (Rmi=660,85 MPa) was obtained in white cast irons with a boron content of 0,23%.
Downloads
References
F. Nurjaman, S. Sumardi, A. Shofi, M. Aryati, and B. Suharno, “Effect of molybdenum, vanadium, boron on mechanical properties of high chromium white cast iron in as-cast condition”, AIP Conference Proceedings, vol.1711, №020005, February 2016. [Online]. Available: https://aip.scitation.org. [Accessed Sept. 28, 2020].
Xiang Chen, Yanxiang Li and Huiming Zhang, “Microstructure and mechanical properties of high boron white cast iron with about 4 wt% chromium”, Journal of Materials Science, vol.46, p.957–963, February 2016. [Online]. Available: https://www.researchgate.net. [Accessed Sept. 27, 2020].
A. Nofal, “Metallurgical Aspects of High- Chromium White Irons”, www.foundry-planet.com. [Online]. Available: https://www.foundry-planet.com/fileadmin/redakteur/pdf-dateien/13-Adel-Nofal.pdf. [Accessed Sept. 27, 2020].
Kh. Abd El-Aziz, Kh. Zohdy, D. Saber and H. E. M. Sallam, “Wear and Corrosion Behavior of High-Cr White Cast Iron Alloys in Different Corrosive Media”, Journal of Bio- and Tribo-Corrosion , vol.1, №25, August 2015. [Online]. Available: https://link.springer.com. [Accessed Sept. 25, 2020].
A. Bedolla-Jacuinde, F. V. Guerra, I. Mejía, J. Zuno-Silva and C. Maldonado,”Boron Effect on the Precipitation of Secondary Carbides During Destabilization of a High-Chromium White Iron”, International Journal of Cast Metals Research, vol.29, issue:1-2, p.55-61, February 2016.[Online].
Available: https://www.tandfonline.com. [Accessed Sept. 25, 2020].
S. Reyna, A. Bedolla-Jacuinde, F.V. Guerra, I. Mejía and M. García, “Effect of amount and distribution of primary TiC on the wear behavior of a 12%Cr-3%C white iron under dry sliding conditions”, Wear, №203718, February 2021.[Online]. https://www.researchgate.net. [Accessed March. 10, 2021].
Kh. Abdel-Aziz, M. El-Shennawy* and Adel A. Omar, “Microstructural Characteristics and Mechanical Properties of Heat Treated High-Cr White Cast Iron Alloys”, International Journal of Applied Engineering Research, vol.12, №14, p.4675-4686, January 2017. [Online].
https://www.researchgate.net. [Accessed March. 2, 2021].
S. M. Tomovic-Petrovic, S. V. Markovic and S. Zec, “The effect of boron on the amount and type of carbides in chromium white irons”, Journal of the Serbian Chemical Society, vol.67(10), p.697–707, January 2002. [Online]. https://www.researchgate.net. [Accessed Sept.. 28, 2020].
K. Ibrahim, ” Investigation of improving wear performance of hypereutectic 15% Cr-2% Mo white irons”, China Foundry, vol.7(4), p.438-446, November 2010. [Online]. https://www.researchgate.net. [Accessed Sept.. 29, 2020].
C. Scandian, C. Boher, J.D.B de Mello and F. Rezai-Aria,
“Effect of molybdenum and chromium contents in sliding wear of high-chromium white cast iron: The relationship between microstructure and wear”, Wear, vol.267, issues:1-4, p.401-408, May 2009.[Online]. https://www.sciencedirect.com. [Accessed Sept.. 29, 2020].
J.D.B. de Mello, A. A. Polycarpou,”Abrasive wear mechanisms of multi-components ferrous alloys abraded by soft, fine abrasive particles”, Wear , vol.269, issues:11–12, p.911-920, October 2010. [Online]. https://www.sciencedirect.com. [Accessed Sept.. 29, 2020].
V.P.Todorov, “Influence of the carbide phase on the mechanical and operational characteristics of bainitic cast irons”, Ph.D. dissertation, Technical University - Gabrovo, Gabrovo, Bulgaria, 2016.
