Investigation of fatigue strength of pack-borided steels at high temperatures

Wear losses are the most important issue of the machinery industry in the world. This situation causes to financial losses of millions of dollars every year. Works on surface treatment are increasing day by day in order to reduce the wear loss of materials. Thermochemical surface treatments are the most ideal method because of their low cost and easy availability. The boriding process is the thermochemical surface treatment which increases wear and fatigue resistance of material used in this study. In this study, AISI 4140 and AISI H13 steels were borided at 900C and 950C for 4 and 6 hours respectively. Microstructures of steels analyzed, hardness, wear and thermal fatigue strengths were measured after the boriding process. Especially, the effect of boriding on the wear resistance was investigated at room temperature and 400 C temperature. At the same time, it is known that the boriding increases the fatigue strength against residual stress occurring on the surface. Therefore the effect of boriding has been investigated on the fatigue at different ambient temperatures. Also AISI 4140 steel has been recommended as an alternative to hot work tool steels used at high-temperature applications because of its lower cost. Keywords: Pack-Boriding, Fatigue Strength, Wear Resistance, AISI H13, AISI 4140 2017, 61 pages