Machinability of titanium aluminides: A review

Abstract

Titanium aluminides are used in the aeronautical and automotive field as an alternative material to manufacture critical components exposed to high temperatures and corrosive environments. These alloys due to its intermetallic structure exhibit some special properties such as low density, high strength, high stiffness, corrosion resistance, and creep resistance. When these components are manufactured, surface integrity is one of the most relevant parameters used to evaluate the quality of the parts. Severe surface integrity problems are reported in the literature, defects such as microstructural alterations, work hardening, residual stresses, surface cracks, among others induced by the cutting process. The surface and sub-surface alteration induced by machining are critical because it will affect the parts performance. Some parameters affect the quality of machined surface. In particular cutting parameters, cutting tools material, tool wear and material properties are the most frequently investigated. Experimental and empirical studies are presented mainly in order to understand the surface integrity induced by machining. This paper provides an overview of the problems associated with the machining process of various types of titanium aluminides. The cutting tools, machining parameters, as well as processing parameters employed to improve machinability and reduce surface defects in titanium aluminides are analyzed and discussed. Particular focus was given to turning and milling process of gamma titanium aluminides. Also, some of the optimal parameters for machining titanium aluminides are presented offering a compilation of the most relevant information from the first to the most recent works that analyze the different aspects that affect the machining of these alloys.

A novel technique for hypersonic vehicle control

“…An extended literature review regarding mechanisms on hypersonic applications, indicates a quite narrow range of materials used. The most common materials for these applications are titanium or aluminum alloys, carbon fibers, reinforced carbon-carbon, ceramics, titanium aluminide alloys and superalloys [17]. In this research, the material evaluation study was conducted on a conceptual level, aiming at an initial material family selection, considering their physical and mechanical properties.…”

Experimental Evaluation of Surface Alterations Induced in Machining of Ti-6Al-4V Alloy

“…In the machining process, the simultaneous presence of thermal and mechanical loads results in microstructural changes and eventually variation of material properties [29]. At the present study, after preparation of the samples, superficial layer of the machined workpieces were photographed using a light optical microscope × 800 ( Figure 6.).…”

Identification and validation of an extended Stewart-Cazacu micromechanics damage model applied to Ti–6Al–4V specimens exhibiting positive stress triaxialities

“…Ti-6Al-4V is present in a wide variety of key components in aeronautical, automotive, military and biomedical industries. [20][21][22][23][24][25] Its crystalline structure at room temperature consists in a combination of two main phases : primary (α − Ti) structure, composed of hexagonal closed plackets crystals (hcp), and secondary (β − Ti) structure, based on body centered cube crystals (bcc). 26 The experimentally observed mechanical behavior of this titanium alloy is complex, exhibiting orthotropy, SD effect and DH effect.…”