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    Effect of the powder particle size on the wear behavior of boronized AISI 304 stainless steel
    (Carl Hanser Verlag, 2015) Gunen, Ali; Kucuk, Yilmaz; Er, Yusuf; Cay, V. Veli; Oge, Mecit; Gok, M. Sabri
    In this study, the AISI 304 steel specimens were boronized with nanoboron of the size of 10-50 nm and commercial Ekabor 3 powders (<1400 mu m) at 950 degrees C to 1000 degrees C for 2 h and 4 h. Boronized steel specimens were characterized via SEM, microhardness and XRD analyses. Abrasive wear behavior of the specimens, boronized at different temperatures and treatment durations, were examined. The fixed ball micro-abrasion tests were carried out using the abrasive slurry, prepared with different SiC powder particle sizes on the boronized specimens at different rotational speeds. The specimens boronized with nanoboron powders exhibited a higher hardness and abrasive wear resistance than the samples boronized with the Ekabor 3 powders.
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    Properties and Corrosion Resistance of AISI H13 Hot-Work Tool Steel with Borided B4C Powders
    (Korean Inst Metals Materials, 2020) Gunen, Ali; Karahan, Ismail Hakki; Karakas, Mustafa Serdar; Kurt, Bulent; Kanca, Yusuf; Cay, Vedat Veli; Yildiz, Murat
    In this study, the surface of AISI H13 steel was borided with powder blends of B4C and NaBF(4)using the powder-pack method at 800, 900 and 1000 degrees C for 2, 4 and 6 h. The structural and mechanical characteristics of the boride layers formed on the surface were characterized using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry, 2D surface profilometry, microhardness and electrochemical corrosion (3.5 wt% NaCl) tests. The boride layer exhibited a single phase structure (Fe2B) in samples coated at 800 degrees C and a dual-phase structure (FeB + Fe2B) at higher boriding temperatures (900 and 1000 degrees C). The boride layers were compact and crack-free in all boriding conditions. Depending on boriding parameters, the thickness, hardness and average surface roughness (R-a) of the coatings were found to range between 5.81 and 102.46 mu m, 1635-1915 HV and 0.315-0.650 mu m, respectively. The borided AISI H13 steel displayed up to 33.5 times and 2.4 times higher corrosion resistance than untreated AISI H13 steel and martensitic AISI 431 steel, respectively. This suggests potential use of borided AISI H13 steel in the steam turbines and marine applications as an alternative to the more costly martensitic and duplex stainless steel grades. The corrosion resistance depended on the phase structure (single- or dual-layer), density, thickness and surface roughness of the boride coatings. Graphic