The effect of hot dip galvanizing process on the fatigue properties of hot rolled and quenched tempered AISI 4340 steel

In this study, the effects of hot dip galvanizing treatment on the fatigue strength of the hot rolled and quenched-tempered aisi 4340 steel were examined. the phase structure, phase thicknesses, surface hardness and roughness values of the galvanized coating were also examined. while the reduction in surface roughness of the part due to the high surface tension of the liquid zinc after galvanization has a positive effect, the decrease in the surface hardness due to the low hardness of the zinc and the decrease in the fatigue resistance are adversely affected. the surface hardness, surface roughness, coating thicknesses and the morphologies of constituent phases of coating obtained in both groups are similar, irrespective of the treatments seen before galvanizing the aisi 4340 steel. although the decrease in fatigue strength after galvanization is higher in qt steel, the positive contribution to fatigue resistance of the quenched and tempered process still continues.