M. Peters

Bio: M. Peters is an academic researcher. The author has contributed to research in topics: Ultimate tensile strength & Fatigue limit. The author has an hindex of 1, co-authored 1 publications receiving 125 citations.

Influence of texture on fatigue properties of Ti-6Al-4V

Abstract: Tensile properties, high cycle fatigue strength, and fatigue crack propagation behavior were evaluated on highly textured Ti-6Al-4V material to investigate the influence of a preferred crystallographic orientation on mechanical properties. Thermomechanical treatments were used to develop three different textures: a basal, basal/transverse, and transverse type, all of which exhibited the same homogeneously equiaxed microstructure. The Young’s modulus was found to vary between 107 and 126 GNm-2, and yield strength changed from 1055 to 1170 MNm-2. Ductility was only slightly affected by texture. High cycle fatigue and fatigue crack growth measurements were performed in vacuum, laboratory air, and a 3.5 pct NaCl solution. It is shown that laboratory air can be regarded as a quite corrosive environment. In vacuum the highest fatigue strength values were measured whenever loads were perpendicular to basal planes. However, these conditions had the highest susceptibilities to air and 3.5 pct NaCl solution environments. Nearly no influence of texture on fatigue crack propagation was found in vacuum, but in a corrosive environment crack growth parallel to (0002)-planes was much faster than perpendicular to these planes. To explain the corrosive effect on the fatigue properties of the textured material hydrogen is thought to play a key role.

Titanium metal matrix composites: An overview

Abstract: Titanium matrix composites (TMCs) offer high specific strength and stiffness compared with steel and nickel-base materials. High-temperature TMCs can offer up to 50% weight reduction relative to monolithic superalloys while maintaining equivalent strength and stiffness in jet engine propulsion systems. Regardless of the reinforcements are continuous fibres or discontinuous particulates, the unique properties of TMCs have thrust them to the forefront of extensive research and development programmes around the world. Even though TMCs are one of the most studied and sought-after material systems, useful information about their properties, fabrication methods and design is scattered in the literature. This review covers important research work that has led to the advances in TMCs material systems. It also provides comprehensive details about common reinforcements, manufacturing processes, and reviews static and dynamic properties of some common TMCs. The review also presents common industrial applications of TMCs and highlights the promising outlook of TMCs.

Influence of microstructure on high-cycle fatigue of Ti-6Al-4V: Bimodal vs. lamellar structures

Abstract: The high-cycle fatigue (HCF) of titanium alloy turbine engine components remains a principal cause of failures in military aircraft engines. A recent initiative sponsored by the United States Air Force has focused on the major drivers for such failures in Ti-6Al-4V, a commonly used turbine blade alloy, specifically for fan and compressor blades. However, as most of this research has been directed toward a single processing/heat-treated condition, the bimodal (solution-treated and overaged (STOA)) microstructure, there have been few studies to examine the role of microstructure. Accordingly, the present work examines how the overall resistance to high-cycle fatigue in Ti-6Al-4V compares between the bimodal microstructure and a coarser lamellar (β-annealed) microstructure. Several aspects of the HCF problem are examined. These include the question of fatigue thresholds for through-thickness large and short cracks; microstructurally small, semi-elliptical surface cracks; and cracks subjected to pure tensile (mode I) and mixed-mode (mode I+II) loading over a range of load ratios (ratio of minimum to maximum load) from 0.1 to 0.98, together with the role of prior damage due to sub-ballistic impacts (foreign-object damage (FOD)). Although differences are not large, it appears that the coarse lamellar microstructure has improved smooth-bar stress-life (S-N) properties in the HCF regime and superior resistance to fatigue-crack propagation (in pure mode I loading) in the presence of cracks that are large compared to the scale of the microstructure; however, this increased resistance to crack growth compared to the bimodal structure is eliminated at extremely high load ratios. Similarly, under mixed-mode loading, the lamellar microstructure is generally superior. In contrast, in the presence of microstructurally small cracks, there is little difference in the HCF properties of the two microstructures. Similarly, resistance to HCF failure following FOD is comparable in the two microstructures, although a higher proportion of FOD-induced microcracks are formed in the lamellar structure following high-velocity impact damage.