Low-Cycle Fatigue and Cyclic Deformation Behavior of Type 16-8-2 Weld Metal at Elevated Temperature

Abstract

The low-cycle fatigue behavior of Type 16-8-2 stainless steel weld metal deposited by the automatic submerged-arc process at 593 ° was investigated, and the results are compared with existing data for Type 316 stainless steel base metal. Tests were conducted under axial strain control and at a constant axial strain rate of 4 x 10−3 s−1 for continuous cyclic loadings as well as hold times at peak tensile strain. Uniform-gage specimens were machined longitudinally from the surface and root areas of a 25.4-mm-thick welded plate and tested in the as-welded condition. Results indicate that the low-cycle fatigue resistance of this weld metal is somewhat better than that of the base metal for continuous-cycling conditions and significantly better for tension hold-time tests. This is attributed to the fine duplex delta ferrite-austenite microstructure in the weld metal. The initial monotonic tensile properties and the cyclic stress-strain behavior of this material were also determined. Because the cyclic changes in mechanical properties are strain-history dependent, a unique cyclic stress-strain curve does not exist for this material.