Effect of plasma welding parameters on the flexural strength of ti-6al-4v alloy

Abstract

The aim of this study was to assess the effect of different plasma arc welding parameters on the flexural strength of titanium alloy beams (Ti-6Al-4V). Forty Ti-6Al-4V and 10 NiCr alloy beam specimens (40 mm long and 3.18 mm diameter) were prepared and divided into 5 groups (n=10). The titanium alloy beams for the control group were not sectioned or subjected to welding. Groups PL10, PL12, and PL14 contained titanium beams sectioned and welded at current 3 A for 10, 12 or 14 ms, respectively. Group NCB consisted of NiCr alloy beams welded using conventional torch brazing. After, the beams were subjected to a three-point bending test and the values obtained were analyzed to assess the flexural strength (MPa). Statistical analysis was carried out by one-way ANOVA and Tukey's HSD test at 0.05 confidence level. Significant difference was verified among the evaluated groups (p<0.001), with higher flexural strength for the control group (p<0.05). No significant differences was observed among the plasma welded groups (p>0.05). The NCB group showed the lowest flexural strength, although it was statistically similar to the PL 14 group (p>0.05). The weld depth penetration was not significantly different among the plasma welded groups (p=0.05). Three representative specimens were randomly selected to be evaluated under scanning electron microcopy. The composition of the welded regions was analyzed by energy dispersive X-ray spectroscopy. This study provides an initial set of parameters supporting the use of plasma welding during fabrication of titanium alloy dental frameworks.

Evaluation of X-shaped welded joints with Co-Cr alloy under different welding parameters: analysis by micro-CT and flexural strength

“…Implantology focused on the oral rehabilitation of edentulous patients has been well-documented and extensively performed, with high success rates. This rehabilitation model, which became known ad modum as the Brånemark Protocol, has been the subject of several studies, both in relation to implants and with respect to the metallic framework (Lyra e Silva, et al 2012;Silveira-Júnior, et al 2012;Castro, et al 2015;Simamoto-Júnior et al, 2015).…”

“…The studies focused on prosthetic frameworks were developed to optimize their production by the use of prefabricated bars and welding techniques other than conventional welding (Lyra e Silva, et al 2012;Silveira-Júnior, et al 2012;Castro, et al 2015;Simamoto-Júnior, et al, 2015). Studies have been conducted to evaluate the types of welding techniques (Wang & Welsch, 1995;Baba & Watanabe, 2005;Rocha, et al 2006;Zupancic, et al 2006;Barbi, et al 2012;Lyra e Silva, et al 2012;Nuñez-Pantoja, et al 2012;Atoui, et al 2013;Castro, et al 2013;Castro, et al 2015;Matos, et al 2015;, the settings of welding equipment (Chai & Chou, 1998;Baba & Watanabe, 2005;Akman, et al 2009; Lyra e Silva, et al 2015), the types of alloys used (Rocha, et al 2006;Watanabe & Topham, 2006;Takayama, et al 2012;Takayama, et al 2013;Lyra e Silva, et al 2015;Matos, et al 2015), the settings of the joints (Zupancic, et al 2006;Nuñez-Pantoja, et al 2012;Takayama, et al 2012;Kokolis, et al 2015;Simamoto-Júnior, et al 2015), and mechanical methods of evaluation of these weld joints (Nuñez-Pantoja, et al 2011;Takayama, et al 2012;Takayama, et al 2013;Castro, et al 2015).…”

“…Among the welding techniques, two have been identified for dental use: laser welding (Berg, et al 1995;Wang and Welsch, 1995;Chai & Chou, 1998;Baba & Watanabe, 2005;Akman, et al 2009;Byrne, 2011;Nuñez-Pantoja, et al 2011;Barbi, et al 2012;Nuñez-Pantoja, et al 2012;Silveira-Júnior, et al 2012;Takayma, et al 2012;Atoui, et al 2013;Castro, et al 2013;Takayama, et al 2013;Castro, et al 2015;Kokolis, et al 2015;Matos, et al 2015) and TIG or plasma welding (Wang & Welsch, 1995;Taylor, et al 1998;Rocha, et al 2006;Byrne, 2011;Barbi, et al 2012;Lyra e Silva, et al 2012;Nuñez-Pantoja, et al 2012;Silveira-Júnior, et al 2012;Atoui, et al 2013;Castro, et al 2013;Castro, et al 2015;Matos, et al 2015;Simamoto-Júnior, et al 2015). Both have some advantages: welding can be performed directly on the model (Chai & Chou, 1998;Baba & Watanabe, 2005;Rocha, et al 2006;Zupancic, et al 2006;Barbi, et al 2012;Silveira-Júnior, et al 2012;Castro, et al 2015), energy can be concentrated in a small area (Rocha, et al 2006;Barbi, et al 2012;Lyra e Silva, et al 2012;…”

“…Regardless of the technique used, studies have shown that the welding machine configuration appears to exert influence on the welding process. Studies have been developed to investigate the influence of parameters such as: current density or electric voltage (peak power) (Chai & Chou, 1998;Baba & Watanabe, 2005;Akman, et al 2009), pulse duration (Chai & Chou, 1998;Baba & Watanabe, 2005;Akman, et al 2009;Lyra e Silva, et al 2012;Takayama, et al 2013), the diameter of the spot weld (Baba & Watanabe, 2005;Akman, et al 2009;Takayama, et al 2013), and the use of the argon shield (Watanabe & Topham, 2006;Akman, et al 2009;Takayama, et al 2012) in penetration depth. Akman et al 2009 studied the effects of different parameters on the laser welding of Ti-6Al-4V specimens in relation to penetration depth and concluded that peak power was the most important parameter, but if that power was increased too much, the temperature of the workpiece exceeded the evaporation point of the alloy and promoted crater formation on the surface of the material.…”

“…The type of alloy has also been studied (Rocha, et al 2006;Watanabe & Topham, 2006;Lyra e Silva, et al 2012;Takayama, et al 2012;Takayama, et al 2013). While titanium alloys are most often used in studies because of their advantages of good compatibility, low density, and anti-corrosion properties (Berg, et al 1995;Chai & Chou, 1998;Taylor, et al 1998;Rocha, et al 2006;Akman, et al 2009;Nuñez-Pantoja, et al 2011;Lyra e Silva, et al 2012;Silveira-Júnior, et al 2012;Takayama, et al 2012;Atoui, et al 2013;Takayama, et al 2013;Castro, et al 2015;Simamoto-Júnior, et al 2015), casting and welding these alloys can be difficult, since titanium, when subjected to high temperatures, has high oxygen, nitrogen, and hydrogen reactivity and can become contaminated, leaving the welded areas of the framework more vulnerable (Berg, et al 1995;Wang & Welsch, 1995;Chai & Chou, 1998;Taylor, et al 1998;Lyra e Silva, et al 2012;Silveira-Júnior, et al 2012;Castro, et al 2015;Akman, et al 2009;Nuñez-Pantoja, et al 2011;Nuñez-Pantoja, et al 2012;Takayama, et al 2012;Atoui, et al 2013;Simamoto-Júnior, et al 2015). Moreover, Co-Cr alloys are increasingly popular in prosthetic dentistry, due to a favorable combination of biocompatibility, resistance to corrosion, castability, weight, stiffness, and low cost (Rocha, et al 2006;Zupancic, et al 2006;Barbi, et al 2012;Kokolis, et al 2015).…”