Properties of borided SAE 1035 steels and fracture toughness produced by Vickers indentation

Boriding in a salt bath consisting of borax, boric acid, ferro-silicon was carried out at a temperature range of 1123, 1173, 1223, and 1273 K, for 4 and 8 h, using a Vickers microhardness tester to generate cracks with applying loads (0.49, 0.98, 1.96, 4.9 and 9.8N). A Vickers indenter was used to estimate the fracture toughness values of borided SAE1035 steel. The microcrack was made through the thickness of the boride layer of SAE1035 steel at different distances from surface. The presence of borides phases was revealed by X-ray diffraction, SEM, and optical microscopy. Experimental results showed that the fracture toughness values obtained using Palmqist crack model were ranged from 2.92 to 3.75 MPa.m 1/2 , increasing of boriding time and temperature leads to reduction of