Issue 48

H. S. Patil et alii, Frattura ed Integrità Strutturale, 48 (2019) 377-384; DOI: 10.3221/IGF-ESIS.48.36 378 In the majority of these and other engineering applications titanium has replaced heavier, less serviceable or less cost effective materials. Designing with titanium taking all factors into account has resulted in reliable, economic and more durable systems and components, which in many situations have substantially exceeded performance and service life expectations. Titanium is available in different grades, unalloyed or alloyed. Unalloyed Commercially Pure (CP) Titanium is available in four different grades, 1, 2, 3 and 4, which are used based on the corrosion resistance, ductility and strength requirements of the specific application. Grade 1 has the highest formability, while Grade 4 has the highest strength and moderate formability. CP Titanium users utilize its excellent corrosion resistance, formability and weldable characteristics in many critical applications. Titanium Grade 2 is stronger than Grade 1 and equally corrosion-resistant against most applications. Titanium Grade 2 is typically used for orthopedic applications, such as implants and prosthesis; airframe and aircraft engine parts; marine chemical parts; condenser tubing; heat exchangers. Titanium Grade 2 may be welded by a wide variety of conventional fusion and solid-state processes, although its chemical reactivity typically requires special measures and procedures. Szymlek has reviewed joining methods for titanium and steel materials by means of explosive welding i.e.by TIG and brazing process and also analyzed FSW analysis of titanium with the use of copper and tantalum or vanadium interlayer [1]. For welding of titanium and its alloys with precise and high quality weld, tungsten inert gas welding (TIG) is ideally suitable. In improving the mechanical properties of the weld, high depth of penetration and low heat affected zone (HAZ) plays an important role [2]. However, the relatively shallow penetration capability and low productivity are the main limitations in the TIG welding process. Attaining full penetration of welds with superior mechanical properties in single pass weld the notable technique was to use activating flux with TIG (A-TIG) welding process [3]. Wang has been used micro-plasma arc welding to weld ultra-thin titanium plates. It is widely used in manufacture of thin-walled titanium tubes, automobile parts, medical and other industrial fields, is an excellent structural material [4]. Krishnanunni studied the effect of welding condition like shielding gas flow rate and numbers of weld passes on hardness of pure titanium material by butt TIG welding [5]. Ugur investigated the multi-response optimization of tungsten inert gas welding (TIG) process for an optimal parametric combination to yield favorable bead geometry of welded joints using the grey relational analysis and taguchi method [6]. Chen discussed the friction stir welding on commercially pure titanium with ADC1 2 cast aluminum alloy using WC-Co tool. Defects arise due to insufficient flow of Ti, causes inhomogeneous distribution. Also due to lower heat input and low reaction time for Ti and Al, decrease in tensile strength was observed [7]. The modified butt joint configuration was employed into the FSW of Ti-6Al-4V alloy to Al-6Mg alloy with a special pin plunge setup by Zhang [8]. The results reveal that the joint mechanical tensile strength can reach more than 92 % of the parent aluminium alloy strength. Kato has stated that Titanium (Ti/Ti) rods and titanium and stainless steel (Ti/SS) rods has been joined by diffusion welding under phase transformation in an air atmosphere [9]. The effect of halide fluxes (NaCl and CaCl 2 ) and welding parameters on welding of Ti-6Al-4V was investigated by Pujari Rao to find optimal setting of parameters for weld penetration and heat affected zone (HAZ). All the parameters on 2-way and 3-way interaction on penetration and interactions on HAZ were found to have significant effect [10]. Zuhailawati has studied the shear strength and micro-structural characteristics of the spot brazed titanium and nickel base metal with and without addition of filler metal by spot resistance welding [11]. Akman has studied about (Ti-6Al-4V) titanium alloys welded by laser welding and found that, the ratio between the pulse energy and pulse duration was the most important parameter in defining the depth of penetration also noted that variation of pulse duration at constant peak power has no influence on the depth of penetration [12]. M ATERIALS & E XPERIMENTAL M ETHODS nalloyed commercially pure titanium Gr-2 sheets are used in this study. The chemical composition and mechanical properties of CP titanium is presented in table-1 and table-2. The dimension of each weld specimen was set 100 mm × 75 mm with thickness of 3 mm. C Fe O N H Ti <0.08% <0.3% <0.25% <0.03% <0.015% Balance Table 1 Chemical specification of workpiece material. U