Effect of Heat Treatment on Very High Cycle Fatigue Properties of TC4

Abstract

The bimodal, equiaxed and Widmanstatten microstructures of TC4 titanium alloy were obtained through different heat treatment processes. The content of primary α phase in the bimodal and equiaxed microstructures was measured to be about 40% and 90%, and the average size was about 9.4μm and 7.9 μm. Three types of microstructure fatigue S-N curves are obtained, which are successively descending type, single-platform descending type and infinite life type. The order of very high cycle fatigue performance is Widmanstatten>equiaxed>bimodal, but the anti-fretting fatigue performance of Widmanstatten is the worst. The grain refinement makes the fatigue performance of the equiaxed better than that of the bimodal. The second process is determined as the best heat treatment method. There is no significant difference in the life of the crack propagation stage. The very high cycle fatigue life mainly depends on the crack initiation stage. In the bimodal and the equiaxed, the crack initiates in the primary α phase of the subsurface, and the crack in the Widmanstatten initiates in the coarse α 'grain boundary of the subsurface.

Research and Analysis of TC4 Titanium Alloy Cutting Based on Crystal Plasticity Theory

“…The focus is fundamental material research and the relationship between microstructure and properties. This paper explores the microstructure and lattice structure of the alpha α phase in TC4 titanium alloy, a representative type of titanium alloy, as illustrated in Figure 1(a) and (b) [9] [10] . Crystal lattice of α and β phases in titanium alloy.…”