Mechanical properties of boronized AISI w4 steel

Abstract

A series of experiments was performed to evaluate some mechanical properties of boronized AISI W4 steel. Boronizing was carried out in a solid medium consisting of EKabor powders at 850, 950 and 1050 C for 2, 4, 6 and 8 h. After boronizing, FeB and Fe2B phases were formed on the surface of the steel substrate. A boride layer was revealed by a classical metallographic techniques and X-ray diffraction (XRD) analysis. Depending on the process temperature and boronizing time, the thickness of the coating layers ranged from 8 to 386 mum. Metallographic studies revealed that the boride layer has a lenticular morphology. The hardness of the boride layer was measured using a Vickers indenter with loads of 0.5 and 1 N. It was found that the hardness of the boride layers ranged from 1407 to 2093 HV The fracture toughness of borided surfaces was measured via a Vickers indenter with a load of 10 N. It was observed that the fracture toughness of the boride layer ranged from 1.39 to 6.40 MPa m(1/2). A longer boronizing time results in a greater boride layer thickness. Lengthwise cracks were formed on the samples that were borided at 1050 C for 6 and 8 h. The distribution of alloying elements from the surface to the interior was determined using energy-dispersive X-ray spectroscopy (EDS). The main aim of present study was to increase the service life of AISI W4 plain carbon tool steel. (C) 2002 Elsevier Science B.V. All rights reserved.