Growth Kinetics and Microstructure of Iron Boride Layers on AISI 1050 Steel

Diffusion kinetics of boron in AISI 1050 steel is investigated. AISI 1050 steel samples are borided for 2, 4 and 6 h at 850, 900 and 950°C by the powder-pack boriding method using Ekabor-II boriding powder. After the powder-pack boriding, about 25.4 – 118.9 μm thick FeB/Fe 2 B boride layers are obtained on the surfaces of the samples. The boride layers have a typical tooth morphology and their hardness is 1071 – 1460 HV 0.1 . The growth rate constants for the boriding temperatures of 850, 900 and 950°C for the AISI 1050 steel are determined to be 1.522 × 10 –12 , 2.964 × 10 –13 and 6.354 ×10 –12 m 2 · sec –1 , respectively. The boron diffusion activation energy in the AISI 1050 steel is 162.93 kJ · mol –1 .