Microstructural characterization and wear resistance of boride-reinforced steel coatings produced by Selective Laser Melting (SLM)

Author(s)

Martins Freitas, Brenda Juliet ^{[1, 2]} ; de Oliveira, Vinicius Antonio ^{[1, 2]} ; Gargarella, Piter ^[1] ; Koga, Guilherme Yuuki ^[1] ; Bolfarini, Claudemiro ^[1]

Affiliation

^[1] Univ Fed Sao Carlos, Dept Mat Engn, BR-13565905 Sao Carlos - Brazil

^[2] Univ Fed Sao Carlos, Grad Program Mat Sci & Engn, BR-13565905 Sao Carlos - Brazil

• Document type: Journal article
• Source: SURFACE & COATINGS TECHNOLOGY; v. 426, NOV 25 2021.
• Web of Science Citations: 0

Abstract

Surface engineering is an effective method to extend the lifespan of carbon steels submitted to severe wear degradation. In this work, the surface of a low carbon steel (AISI 1020) was protected by a boron-modified stainless steel coating produced by selective laser melting (SLM). Commercial precursors such as 2205 duplex stainless steel and ferrous-alloy (Fe-B) were used to produce boron-modified steel powders by two different routes: i) gas atomization, and ii) gas atomization followed by mechanical milling of large particles (to reduce the particles' size and to add a solid lubricant - hexagonal boron nitride, h-BN). Thick coatings (200 - 600 mu m) metallurgically bonded to the substrate were produced with reduced dilution, characterized by refined, hard and rigid borides homogeneously distributed within the predominant ferritic matrix. The boron-modified steel coatings were hard (similar to 800 HV0.5) and wear-resistant, since the specific wear rate was similar to 4.5 x 10(-5) mm(3).N-1.m(-1), much inferior to that of the soft (similar to 120 HV0.5) AISI 1020 substrate (similar to 1.8 x 10(-3) mm(3).N-1.m(-1)). Although recognized as solid-lubrificant, the coating produced by powder containing h-BN additions did not exhibit reduced coefficient of friction. Given the high temperatures achieved during SLM process, the h-BN may decompose, being the remaining content insufficient to enable the formation of an effective lubrificating layer. The present work contributes to widespread the use of SLM to produce wear-resistant protective coatings using boride-reinforced stainless steels. (AU)

• FAPESP's process: 17/27031-4 - Effect of process parameters on the metallurgical characteristics of additive-manufactured alloys
• Grantee: Piter Gargarella
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 18/23810-1 - Investigation about the possibility of hexagonal boron nitride formation to superduplex stainless in order to reduce friction coefficient
• Grantee: Vinicius Antonio de Oliveira
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 19/05885-7 - Microstructure, mechanical properties and corrosion resistance of boron-modified stainless steels processed by additive manufacturing
• Grantee: Brenda Juliet Martins Freitas
• Support Opportunities: Scholarships in Brazil - Doctorate