Ultra-Fast Boriding and Surface Hardening of Low Carbon Steel

Abstract

Ultra-fast surface hardening of low carbon steel is introduced via the application powder-pack boriding process in a hot isostatic pressing special fixture. Boriding (Boronizing) powder consisting of boric acid and borax mixture is utilized in 50 wt. % boric acid and 50 wt. % of borax. Low carbon steel sample packed with boric acid and borax, heated at 1050°C for 30 minutes and then at tempered 900oC for 30 minutes in a special fixture sealed with a 10 Ton pressure. The surface boride layer as FeB and Fe2B phase with the hardness about ~1800 HV and depth of 130–180 μm is achieved and compared to untreated base metal of 123 HV. Alloy segregation along with delocalized zone of interest is achieved with different boron content 1.77 wt. % along grain boundaries, 3.93 wt. % leading phase and 7.86 wt. % trailing phase at the sample surface. This process provides high performance and high thickness of coatings and can be used fast and economically if compared to traditional processes with less emission. From economic and environmental points of views, it is highly desirable to develop and implement novel surface treatment technologies that are quick, cheap, clean, and energy efficient.