Mechanical behavior of borides formed on borided cold work tool steel

In this study, some mechanical properties of borided cold work low-alloy to ol steels were investigated. Boronizing was performed in a solid medium con sisting of Ekabor-I powders at 1000 degreesC for 2, 4 and 6 h. The substrat e used in this study was high-carbon, low-alloy tool steel essentially cont aining 1.18 wt.% C, 0.70 wt.% Cr, 0.30 wt.% Mn, 0.10 wt.% V and 0.25 wt.% S i. The presence of borides (FeB + Fe2B) formed on the surface of steel subs trate was confirmed by optical microscope and X-ray diffraction (XRD) analy sis. The hardness of the boride layer formed on the surface of the steel su bstrate and unborided steel substrate were 1854 and 290 kg/mm(2), respectiv ely. Experimental results revealed that longer boronizing time resulted in thicker boride layers. Optical microscope cross-sectional observation of th e borided layers revealed denticular morphology. The fracture toughness of the boride layers measured by means of a Vickers indenter with a load of 3 N was in the range of 2.52-3.07 MPa m(1/2). (C) 2001 Elsevier Science B.V. All rights reserved.