Classic Ti-3Al-2.5V Seamless Tubing Engineering Guide Now Available as Ebook
The writing of Ti-3Al-2.5V Seamless Tubing Engineering Guide—now being made available to ITA members as an Ebook—came about because of an unmet need in the titanium industry. “In the 1980s, everybody wanted information about Ti-3Al-2.5V for seamless tubing and there wasn’t much written down,” recalls Clyde Forney, then director of sales for Sandvik Special Metals in Kennewick, Washington. “So out of necessity, I put together an eight-page guide that I could hand out to clients on sales calls. The first clients who received it were engineers at NASA, and they really appreciated it.” A few years later, he lengthened the guide considerably, including new research. Then in 1990, Forney worked with Steven Meredith, a metallurgist at Sandvik Special Metals, to expand it yet again, adding valuable data on welding, bending, and fatigue properties along with numerous photos, charts, and graphs. Of particular importance was the section on inspection, testing, and quality control. They also added information on consumer applications, including sports, medical, and industrial.
By then, the little eight-page guide had grown to 145 pages in length and was more in demand than ever. Out-of- print for several years—but not out-of-date—its reissuance as an Ebook is part of ITA’s ongoing effort to provide its members with the best information available about all aspects of titanium, whether the information appeared yesterday or, in the case of the Ti-3Al-2.5V Seamless Tubing Engineering Guide, twenty-five years ago.
Like many alloys developed in the 1950s and 1960s as alternatives to Ti- 6Al-4V and CP titanium, Ti-3Al-2.5V was originally developed for aerospace applications. The specific need was for seamless tubing that would decrease the weight of the hydraulic system in aircraft while providing high strength properties. The alloy Ti-6Al-4V was not a viable option because its ductility level made the manufacture of tubing difficult. CP titanium did not have enough strength for most hydraulic applications. Only Ti- 3Al-2.5V was suitable. A lean alpha plus beta alloy that uses the same alloying elements as Ti-6Al-4V, it is sufficiently malleable for tube manufacture. It can be cold-worked using standard tube making processes, is weldable, and can be strengthened by a combination of cold working and subsequent heat treating to a wide range of strengths and ductilities.
The U.S. military started using Ti-3Al-2.5V in the late 1960s in the hydraulic lines of the F-14 Tomcat manufactured by Grumman. It was also used in the Lockheed C-5A. After it became standard in military aerospace, the alloy found its niche in civilian aircraft, including Boeing’s 767. It was also used in engines built by Pratt & Whitney and General Electric.
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But what set Ti-3Al-2.5V apart from many other alloys was its applicability for consumer goods, not just aerospace—an aspect about which Clyde Forney can shed some light. Forney started out in the industry 56 years ago in 1959 as a chemist for Wah Chang Metals Corp., eventually moving into sales. In 1977 while working for Zirtech, a company that had originally made zirconium tubing for the nuclear industry and which had diversified into titanium, Forney got a phone call from two Italian bicycle enthusiasts interested in building a brazed titanium bicycle. Pino Morroni was a former Italian soccer star who had become a bicycle frame designer. Cecil Behringer was a titanium brazing engineer. “They asked if they could sit down with me to explore the use of titanium tubing. Working together, we picked material sizes and wall thickness, and then we designed and built a brazed bicycle frame with titanium alloy tubing,” Forney explained. “To prove the strength of the frame, Morroni rode his bike down the steps of the Victor Emmanuel Monument in Rome.” While the bicycle never went into full production, the use of Ti-3Al-2.5V in the frame brazed in a oxygen-free oven advanced the art, demonstrating that titanium could bring its legendary strength and light weight into the world of cycling.
Around the same time, Teledyne Linair in Gardena, California, introduced titanium frames using modified CP titanium tubing. But there were many technical problems. Frames made of CP titanium were light and resilient but often they broke down under strenuous racing conditions. Ti-6Al-4V, the dominant alloy in aerospace, was also tried by some frame manufacturers but without success. Ti-3Al-2.5V proved to be superior to both CP titanium and Ti-6Al-4V. Machine shops liked the alloy because it is weldable and its machinability is comparable to stainless steels, so experienced machinists could use conventional techniques.
The market for titanium bikes took off in the 1980s when mountain biking became popular. High strength coupled with weight reduction was not as necessary for street bikes as it was for mountain bikes that had to be able to withstand grueling dirt trails strewn with rocks. The American manufacturers Merlin and Litespeed (now part of Merlin) brought titanium bikes to the fore using Ti-3Al-2.5V supplied by Sandvik Special Metals. Besides the reduction in weight, riders appreciated the alloy’s corrosion resistance and natural dampening characteristic, which made for a smoother ride. The new titanium bicycles were expensive but tough. Suddenly cyclists had the ability to ride rough back-country trails without demolishing their bikes.
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While at Zirtech in the 1970s, Forney was also involved in researching the use of Ti-3Al-2.5V for golf clubs. The alloy is well suited for shafts because it is resistant to twisting or torque during the swing. This property also makes it ideal for tennis rackets, lacrosse sticks, and other sports equipment. “One day a man who had the idea of making titanium golf shafts, and who had the patents to back it up, contacted me at Zirtech and asked for a meeting,” Forney said. “The local management thought the golf shafts had a chance of being a viable product, so we set up an area in one of our buildings so he could conduct swaging research and rough finishing of shafts.” Subsequently, Zirtech developed a manufacturing program for the golf shafts, which were produced by swaging Ti-3Al-2.5V tubes into tapered shapes, heat-treating, cutting to length, and polishing. Then they were weighed, cut to exact shaft number length, and bagged. Unfortunately, a few years later, Zirtech decided to refocus its business on aerospace and cancelled the program. However, that was not the end of the line. When Forney joined Sandvik Special Metals as director of sales in 1981, he got back in touch with the man, the result being the production of Sandvik’s Ti-Shaft product. “Sandvik eventually stopped making golf shafts, finding it more lucrative to sell Ti-3Al-2.5V seamless tubing to all the major bicycle makers,” said Forney. “It was the perfect alloy for sports equipment.”
Even with its increasing importance in consumer products, the alloy’s main use continued to be in aerospace where the strength-to-weight ratio has always been a critical factor. One of Forney’s milestones during that time was his work with NASA and Rockwell Space engineers on changing the hydraulic lines in the space shuttle from steel to Ti-3Al-2.5V seamless tubing. This change significantly reduced the weight of the shuttle. Because it is corrosion resistant, the alloy was also appropriate for boilers and pressure vessels. In the 1980s, Ti-3Al- 2.5V was listed as ASTM Grade 9 and was approved by the American Society of Mechanical Engineers (ASME).
Forney was involved in yet one more innovative consumer use of Ti-3Al- 2.5V, this time in wheelchairs. Besides high fracture toughness, titanium has a low elastic modulus, which provides a dampening effect for a smoother ride. Related to stiffness and the ability to transmit shock waves, a low elastic modulus helps absorb the bumps. Plus titanium does not corrode or rust.
Ti-3Al-2.5V is the preferred alloy for off- road, racing, and basketball wheelchairs, in fact, for all wheelchairs.
The availability of Ti-3Al-2.5V Seamless Tubing Engineering Guide in Ebook format is a welcome addition to ITA’s online library. Ebooks are an efficient and cost-effective way to provide our members with quality information on titanium. We look forward to adding other titles, and we thank Clyde Forney for his willingness to make his excellent book available.
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