Titanium investiment casting defects: A metallographic overview

Abstract

Although titanium castings have been used in aerospace structures for decades, those uses have largely been in secondary applications. Expanding the use of titanium castings in critical applications would be encouraged by a better understanding of investment casting defects in titanium alloy systems. This paper describes several types of casting-related defects that are identifi ed as potentially affecting the design life of a structure: inclusions, voids, and weld repair defects.

Microstructural evolution and mechanical properties of powder metallurgy Ti–6Al–4V alloy based on heat response

“…Therefore, near-net-shape technologies, like investment casting and powder metallurgy (PM), are required. Investment casting is the most cost-effective way, but the casting defects, such as casting porosity, composition and microstructure variation, and ceramic inclusions [4][5][6][7], can inevitably exist, which will degrade the mechanical properties. PM route is being studied essentially as a technology upgrade of precision casting, and it can achieve more uniform and homogenous microstructure and isotropic properties through HIPing process.…”

The effect of ageing on microstructure and mechanical properties of powder Ti–5Al–5Mo–5V–1Cr–1Fe alloy

“…landing gears, airframe, compressor discs and blades, spacers and gas turbine engines [2,3]. However, castings inherit some essentially unavoidable defects, such as macro-segregation, microsegregation, porosity, solidification shrinkage and second phase inclusions [3][4][5]. In addition, only ~10% of the material's initial weight is utilised [6] resulting in high processing costs.…”

The Ideal Hybrid Framework Material? - A Literature Review

“…Titanium, a material with superior qualities such as biocompatibility (13), corrosion resistance, low cost and good mechanical properties (14) was a popular choice for the framework. However, it was difficult to cast due to its high melting temperatures, low density, and reactivity with elements in casting investments (15).This problem could be overcome with the advent of digital manufacturing which may help us avoid the limitations posed by manual casting of titanium (16).…”