Fatigue Properties of Tungsten Heavy Alloys IT180 and D176
Tutor / director / evaluatorIyengar, Srinivasan
Document typeMaster thesis (pre-Bologna period)
Rights accessOpen Access
Fatigue properties of the tungsten-based alloys IT180 (W-3.5Ni-1.5wt%Cu) and D176 (W-5Ni-2.5wt%Fe) have been determined using constant amplitude stress-controlled fatigue tests. These tests were performed at room temperature at relatively high cycle fatigue lives. The results indicate that the endurance limit for the alloys is about 210 MPa for IT180 and 425 MPa for D176. The fatigue strength coefficients and fatigue strength exponents are and for IT180 and and for D176. Strain-controlled fatigue tests were also performed to complement the stress-controlled experiments. The Multiple Step Test method was used to estimate the cyclic stress-strain curves of the alloys. The tests indicate hardening of both materials when subjected to cyclic loading. The cyclic strain hardening exponent of D176 was possible to find and was estimated to . The fatigue response of the material is strongly affected by surface roughness, residual porosity, pore size and pore distribution. A finite element analysis was made to understand the effect of specimen geometry on the fatigue data. The results showed that specimen geometry affects stress concentrations and stress distribution, which might be related to the failure of the specimen. Scanning electron microscopy and energy dispersive spectroscopy have been used to characterize the sample’s microstructures and fracture surfaces.