Titanium is a crucial component in aerospace and defense applications as well as in the biomedical field. The high ratio of strength to density of titanium and its alloys mean that it is as strong as some steels, but with a fraction of the density. However, titanium is more difficult than steel to prepare as a metallographic sample due to its ductile nature that renders it easily susceptible to damage.
In this HTTBest of the Web Technical Tuesday feature, Buehler’s Tech Notes explores efficient preparation of titanium grade 2 samples.
An excerpt: “Titanium and its alloys’ high strength to density ratio and good corrosion resistance make them invaluable in aerospace, defense, and marine applications. Good biocompatibility also makes it quite useful in biomedical applications. It is as strong as some steels but a fraction of steel’s density. When preparing metallographic samples, one quickly learns, titanium is more difficult to prepare than steel as it ductile and readily damaged, but also has a relatively slow material removal or recovery rate, which poses a challenge to sample preparation.”
Buehler takes readers through the methods of sectioning, mounting, grinding and polishing, and etching when preparing grade 2 titanium for a sample.
A new category of high-performance titanium-copper alloys for 3D printing is being considered for medical device, aerospace, and defense applications, and heat-treating may improve the process further.
In a collaborative project, leading researchers from RMIT University, CSIRO, the University of Queensland, and The Ohio State University studied the problem of titanium alloys being prone to cracking or distortion due to cooling and bonding together in column-shaped crystals during the 3D printing process. But a titanium-copper alloy developed by the research team seems to have solved this dilemma.
“Of particular note was its fully equiaxed grain structure,” said Professor Mark Easton from RMIT University’s School of Engineering in Today’s Medical Developments. “This means the crystal grains had grown equally in all directions to form a strong bond, instead of in columns, which can lead to weak points liable to cracking. Alloys with this microstructure can withstand much higher forces and will be much less likely to have defects, such as cracking or distortion, during manufacture.”
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CSIRO Senior Principal Research Scientist, Dr. Mark Gibson, says their findings also suggest similar metal systems could be treated in the same way to improve their properties.
“Titanium-copper alloys are one option, particularly if the use of other additional alloying elements or heat treatments can be employed to improve the properties further,” Gibson says. “But there are also a number of other alloying elements that are likely to have similar effects. These could all have applications in the aerospace and biomedical industries.”
Titanium alloys have a high tensile strength because of density ratio, high corrosion resistance, and ability to withstand moderately high temperatures without creeping. Because of these features, titanium alloys are used for aircraft development. This article, from Outlook Biz, highlights the research done by IRT Saint Exupery in which they assessed the potential use of the Ti-6Al-4V ELI alloy in aerospace applications, specifically in relation to heat treatment and fatigue crack growth.
“Researchers from IRT Saint Exupery assessed the impact of microstructure on the fatigue crack growth resistance of αβ titanium alloys.“
The study was led by James Pikul, Assistant Professor in the Department of Mechanical Engineering and Applied Mechanics at Penn Engineering.
We’ve come a long way in the search for and application of lightweight metals, which are being used now in everything from high-performance golf clubs to airplane wings, but random defects that arise in the manufacturing process mean that these materials are only a fraction as strong as they could theoretically be.
In a new study published in Nature Scientific Reports, researchers at the University of Pennsylvania’s School of Engineering and Applied Science, the University of Illinois at Urbana–Champaign, and the University of Cambridge have designed and built materials that are stronger than anything heretofore developed, using a sheet of nickel with nanoscale pores that make it as strong as titanium but four to five times lighter.
“The empty space of the pores and the self-assembly process in which they’re made make the porous metal akin to a natural material, such as wood.
And just as the porosity of wood grain serves the biological function of transporting energy, the empty space in the researchers’ “metallic wood” could be infused with other materials. Infusing the scaffolding with anode and cathode materials would enable this metallic wood to serve double duty: a plane wing or prosthetic leg that’s also a battery.”
Photo credit/caption: Penn Engineering/A microscopic sample of the researchers’ “metallic wood.” Its porous structure is responsible for its high strength-to-weight ratio, and makes it more akin to natural materials, like wood.
Dogs come in all shapes, sizes, and colors, and in the case of certain breeds, they are also prone to higher incidences of hereditary defects, deformities, or infirmities.
Dr. Kevin Parsons, an orthopedic veterinarian, Langford Vets
Small dogs can present particular health issues that are a challenge to correct because their size and weight offer little to no margin for error. In dachshunds and Shih Tzus, abnormal bone growth can sometimes cause their front paws to point outwards. And pugs, and other breeds with corkscrew tails, are susceptible to spinal problems caused by misshapen bones. Fortunately, if diagnosed in time, these conditions can be treated with surgery, but with such small animals, corrective surgery to drill and cut bones, stabilize vertebrae or reposition limbs is a laborious and intricate process.
Two animal specialists from Britain, Dr. Kevin Parsons, an orthopaedic vet based at the small animal hospital at Langford Vets, in Bristol, and a former colleague Tom Shaw a neurosurgeon, now at Willows Veterinary Centre and Referral Service in Solihull are pushing the boundaries of additive manufacturing in veterinary science and are applying it to both scenarios. They have been exploring the world of 3D-printed anatomical guides and titanium implants, manufactured on a GE Additive Arcam EBM Q10plus in South Wales, as a means to provide animals suffering from malformation an opportunity to live longer, pain-free lives.
Integral to Langford Vets’ additive journey has been its partnership with Swansea-based CBM Wales (CBM) – a commercially focused advanced research, product development and batch manufacturing facility, established by the University of Wales Trinity Saint David.
Dr. Ffion O’Malley, CBM Wales
Dr. Ffion O’Malley and an experienced team of additive manufacturing designers and engineers at Swansea-based CBM Wales (CBM) — a commercially focused advanced research, product development and batch manufacturing facility, established by the University of Wales Trinity Saint David — oversee production of bespoke surgical guides (either in polymer or metal) and titanium implants to match exactly to each individual patient’s anatomy to restore mechanical and/or aesthetical functions. Each implant design, follows precise specifications from the Langford Vets’ surgical team, using CT or MRI diagnostic imaging data.
Diagnosis: Topsey (pictured above), at aged one, was diagnosed by Tom Shaw with hind limb weakness caused by a severe spinal malformation. CBM Wales were briefed to produce a stabilisation implant required to work in conjunction with a surgical drilling guide.
Surgical Guide: Five drill cylinders were used to guide the pilot drill to achieve the correct trajectories. The bone bound surface of this surgical guide contoured the spinal anatomy so that it located and fit accurately onto the bone.
Implant: Ten screw holes were designed onto the implant and located in the same position as the drill cylinders to achieve the correct trajectories. The bone bound surface of this Titanium implant contoured the spinal anatomy so that it located and fit accurately onto the bone.
The Q10plus is particularly well-suited for medical implant manufacture and has been developed for easy powder handling and fast turnaround times. The EBM process takes place in a vacuum and at elevated temperatures, which results in stress-relieved implants with properties better than cast and comparable to wrought materials.
The bespoke implants are built in Titanium Ti6Al4V ELI, which is certified to the USP Class VI standard for biocompatibility and is extensively used for FDA and CE marked implants. CBM has ISO 9001:2015 certification for the provision of a design, prototyping and small batch manufacturing service and ISO 13485:2016 & EN ISO 13485:2016 certification for the design and manufacture of custom made 3D-printed surgical guides and implants.
The first titanium wheel created using EBM technology was recently unveiled during the official announcement of a partnership agreement between the two companies responsible for its design and manufacture.
HRE Wheels, headquartered in Vista, California, and GE Additive launched the new technology, which is a type of 3D printing to test the capabilities of additive manufacturing in a practical application and to create a highly-sophisticated wheel design with an elusive material like titanium. The new prototype wheel is known as “HRE3D+”.
With a traditional aluminum Monoblok wheel, 80% of material is removed from a 100-pound forged block of aluminum to create the final product. With additive manufacturing, only 5% of the material is removed and recycled, making the process far more efficient. Titanium also has a much higher specific strength than aluminum and is corrosion resistant, allowing it to be extremely lightweight and to be shown in its raw finish.
There was an intensive design collaboration between the Vista, California-based, team at HRE and the GE AddWorks team out of Ohio. Using design queues from two existing models of HRE wheels, the two companies worked together to create a stunning example of what is possible with additive manufacturing.
HRE President Alan Peltier
The wheel was produced on two Arcam EBM machines – Q20 and a Q10 in five separate sections, then combined using a custom center section and titanium fasteners.
“This is an incredibly exciting and important project for us as we get a glimpse into what the future of wheel design holds,” said HRE President Alan Peltier. “Working with GE Additive’s AddWorks team gave us access to the latest additive technology and an amazing team of engineers, allowing us to push the boundaries of wheel design beyond anything possible with current methods. To HRE, this partnership with GE Additive moves us into the future.”
Robert Hanet, senior design engineer, GE Additive AddWorks
“HRE prides itself on its commitment to excellence and superior quality in the marketplace. It was a natural fit for AddWorks to work on this project with them and really revolutionize the way wheels can be designed and manufactured,” said Robert Hanet, senior design engineer, GE Additive AddWorks.
A French manufacturer of high-performance automobiles has developed the largest titanium functional component produced by additive manufacturing in a 45-hour process that includes heat treating to achieve minimum weight with maximum stiffness.
The development department of Bugatti Automobiles, S.A.S., which established itself as a pioneer for new technical developments and innovations in the extreme performance sector of the auto industry with the Veyron and Chiron super sports car models, recently announced the successful design of an eight-piston monobloc brake caliper that can be produced by 3-D printing. Bugatti, in cooperation with Laser Zentrum Nord of Hamburg, bypassed aluminum and turned to aerospace-grade titanium alloy, with the scientific designation of Ti6AI4V, for a tensile strength of 1,250 N/mm2. This means that a force of slightly more than 125 kg (276 lbs.) be applied to a square millimeter of this titanium alloy without the material rupturing.
The development time for the 3-D-printed titanium brake caliper was about three months. The basic concept, the strength and stiffness simulations and calculations and the design drawings were sent to Laser Zentrum Nord by Bugatti. The institute then carried out process simulation, the design of the supporting structures, actual printing and the treatment of the component. Bugatti was responsible for finishing.
The printing process results in a brake caliper complete with supporting structure which maintains its shape until it has received stabilizing heat treatment and reached its final strength. Heat treatment is carried out in a furnace where the brake caliper is exposed to an initial temperature of 1,292°F (700°C), falling to 212°F (100°C) in the course of the process to eliminate residual stress and to ensure dimensional stability.
The new titanium brake caliper, which is 16.2 in. long (41 cm), 8.2 in. wide (21 cm) and 5.4 in. high (13.6 cm), weighs only 6.4 lbs. (2.9 kg). In comparison with the aluminum component currently used, which weighs 10.8 lbs. (4.9 kg), Bugatti could, therefore, reduce the weight of the brake caliper by about 40% at the same time as ensuring even higher strength by using the new part. The result is a delicately shaped component with wall thicknesses between a minimum of only one millimeter (.039 in.) and a maximum of four millimeters (.157 in.).
“It was a very moving moment for the team when we held our first titanium brake caliper from the 3-D printer in our hands,” said Frank Götzke, head of New Technologies in the Technical Development Department of Bugatti Automobiles S.A.S, which is a brand of Volkswagen AG. “In terms of volume, this is the largest functional component produced from titanium by additive manufacturing methods. Everyone who looks at the part is surprised at how light it is – despite its large size. Technically, this is an extremely impressive brake caliper, and it also looks great.”
The first trials for use in production vehicles are due to be held in the first half of the year.
Researchers at the Department of Energy’s Pacific Northwest National Laboratory found a way to double the strength of steel by using a heat treatment process. Read more to get the details of the process….
“Titanium is the leading material for artificial knee and hip joints because it’s strong, wear-resistant, and nontoxic, but an unexpected discovery by Rice University physicists shows that the gold standard for artificial joints can be improved with the addition of some actual gold.”
Read More: Titanium + Gold = New Gold Standard for Artificial Joints by Jade Boyd and Co-Authors Pulickel Ajayan, Sruthi Radhakrishnan and Chandra Sekhar Tiwary, all of Rice; Tiglet Besara, Yan Xin, Ke Han and Theo Siegrist, all of Florida State; Fevzi Ozaydin and Hong Liang, both of Texas A&M; and Sendurai Mani of MD Anderson
Source: Buehler
