IP: 188.72.127.29 On: Mon, 01 Oct 2018 21:47:20 Copyright: American Scientific Publishers Delivered by Ingenta Copyright © 2017 American Scientific Publishers All rights reserved Printed in the United States of America Article Journal of Nanoscience and Nanotechnology Vol. 17, 8946–8951, 2017 www.aspbs.com/jnn Effect of Boriding Treatment on the Corrosion Behavior of Steels Yavuz Ergun 1 , Ibrahim Gunes 2 , Muzaffer Erdogan 3 , and Nevin Cankaya 4 ∗ 1 Department of Chemical Engineering, Faculty of Engineering, Usak University, Usak 64200, Turkey 2 Department of Metallurgical and Materials Engineering, Faculty of Technology, Afyon Kocatepe University, Afyonkarahisar 03200, Turkey 3 Department of Automotive Engineering, Faculty of Technology, Afyon Kocatepe University, Afyonkarahisar 03200, Turkey 4 Nevin Cankaya, Department of Chemistry, Faculty of Science, Usak University, Usak 64200, Turkey In this study, the corrosion behaviors of AISI 420 and AISI 5120 steels borided in Ekabor-II powder at a temperature of 950  C for 5 h were investigated in a 4% M HCI acid solution. The proper- ties of the boride layer were evaluated by optical microscopy, X-ray diffraction, the micro-Vickers hardness tester. X-ray diffraction analysis of the boride layers on the surface of the steels revealed the existence of FeB, Fe 2 B and CrB compounds. The boride layer thickness on the surface of the AISI 420 and AISI 5120 steels was found to be 50.62 m and 148.74 m, respectively depending on the chemical composition of the substrates. The hardness of the boride compounds formed on the surface of the AISI 420 and AISI 5120 steels ranged from 1854 to 2147 HV 0 05 and 1498 to 1892 HV 0 05 respectively, whereas the Vickers hardness values of the untreated steels AISI 420 and AISI 5120 were 340 HV 0 05 and 224 HV 0 05 , respectively. The corrosion resistance of the borided steels was higher compared with that of the unborided steels. The borided steels increased the corrosion resistances of the steels 6–8-fold. Keywords: AISI 420, AISI 5120, Boride Layer, Micro-Hardness, Corrosion. 1. INTRODUCTION Martensitic stainless steels have been used in components operating under wear, corrosion and wear-corrosion condi- tions found in distillation towers, slurry pumps and mixers of chemical products. Martensitic stainless steels are hard- enable by heat treatments, and are usually less resistant to corrosion than some other grades of stainless steel. 1 2 Therefore, there has been extensive research in recent years on the development of surface treatment processes to improve the wear resistance, corrosion and oxidation resistance of steels for high-temperature and high-pressure applications. Industrial boriding processes can be applied to a wide range of steel alloys including carbon steel, low alloy-steel (AISI 5120), tool-steel and stainless-steel. 3–8 Thermal diffusion treatments of boron compounds used to form iron borides typically require process temperatures of 700 and 1000  C. The process can be carried out in solid, liquid, gaseous or plasma media. 8–11 Because of their relatively small size and very mobile nature, boron atoms, can diffuse into ∗ Author to whom correspondence should be addressed. substrate materials. The diffusion of B into steel results in the formation of iron borides (FeB and Fe 2 B) and the thickness of the boride layer is determined by the temper- ature and treatment time. The corrosion of borided steels has not yet been explored extensively; only a few studies have been reported. 16–18 In these studies, the corrosion resistance of some borided steels was evaluated in several acid solutions (H 2 SO 4 , and H 3 PO 4  for different exposure periods using two different methods: the potentiodynamic polarization experiment and the inmersion corrosion test. The corro- sion resistance of boride-coated steels greatly depended on the amount of porosity and micro cracking in the coat- ing. A porous or cracked coating permits the penetration of a corrosive medium to the base material, which could cause rapid corrosion damage if the base material is not inherently corrosion resistant. 19 20 In the present study, the corrosion resistance behaviors of borided AISI 420 and 5120 steels in a 4% M HCI acid solution is examined. The purpose of the study is to explore whether iron boride diffusion coatings could pro- tect steels from aggressive corrosion environments or not. 8946 J. Nanosci. Nanotechnol. 2017, Vol. 17, No. 12 1533-4880/2017/17/8946/006 doi:10.1166/jnn.2017.14251