Amorphous steel powder metallurgy alloy has highest impact resistance
April 13, 2016
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The University of California San Diego announces that a team of engineers has developed and tested SAM2X5-630, a type of amorphous steel with a record-breaking ability to withstand impact without deforming permanently. To make the solid materials that comprise the alloy, Prof. Olivia Graeve and her team first mixed iron and other powders in a graphite mold. The powders were then pressurized at 100 MPa or 1000 atmospheres, and exposed to a powerful current of 10,000 amperes at 1165°F during a process called spark plasma sintering.
The process creates an amorphous structure that contains small crystalline regions that are only a few nanometers in size. Researchers believe that these small regions are key to the material's ability to withstand stress. This finding is promising because it shows that the properties of metallic glasses can be fine-tuned to overcome shortcomings such as brittleness, which have prevented them from becoming commercially applicable on a large scale.
Researchers at the University of Southern California, led by Prof. Veronica Eliasson, tested how the alloy responds to shock without undergoing permanent deformation by hitting samples of the material with copper plates fired from a gas gun at 500 to 1300 meters per second. The material did deform on impact, but not permanently.
The Hugoniot Elastic Limit is defined as the maximum shock a material can take without irreversibly deforming. The limit of a 1.5-1.8 mm-thick piece of SAM2X5-630 was measured at 11.76 GPa. By comparison, stainless steel has an elastic limit of 0.2 GPa, while that of tungsten carbide is 4.5 GPa.
The primary focus of future research efforts on these alloys is increasing the weight of the materials to make them more resistant to impacts.
In addition to Prof. Graeve and Prof. Eliasson, co-authors include Prof. Gauri R. Khanolkar and Prof. Andrea M. Hodge at USC, Prof.Michael B. Rauls at Caltech, and Prof. James Kelly from the Department of Mechanical and Aerospace Engineering at UC San Diego.
This research was supported by the Defense Threat Reduction Agency, grant HDTRA1-11-1-0067.
The full study "Shock Wave Response of Iron-based In Situ Metallic Glass Matrix Composites," published on March 2, can be found online at http://www.nature.com/articles/srep22568
http://jacobsschool.ucsd.edu/
The University of California San Diego announces that a team of engineers has developed and tested SAM2X5-630, a type of amorphous steel with a record-breaking ability to withstand impact without deforming permanently.
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H.C. Starck joins WPI Center for Heat Treating Excellence
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H.C. Starck, Newton, Mass., announces that it has joined the team at the Worcester Polytechnic Institute's Center for Heat Treating Excellence, an alliance between the industrial sector and university researchers that addresses short- and long-term needs in the heat treating and thermal processing industry. Membership in CHTE is unique because members have a voice in selecting quality research projects that help them solve today's business challenges globally.
With close to 100 years of metallurgy experience in the technology metals molybdenum, tantalum, niobium, and tungsten, H.C. Starck has a wealth of research, technical knowledge, and experience to share.
"With our commitment to quality and technological expertise, we work side by side with our customers to ensure they have the highest quality product," says Dmitry Shashkov, Member of H.C. Starck's Executive Board and Head of the Fabricated Products Division. "We are also rapidly growing our business to match the demands of the global marketplace, working with OEM and aftermarket furnace manufacturers on their new designs. To match this growth, H.C. Starck has made significant investments in our fabrication capabilities, and we are leading the development of new materials for high-temperature applications to improve cost and performance for our customers."
H.C. Starck supplies fabricated products to OEMs, end-users, and aftermarket furnace manufacturers for heat treating medical, aerospace, defense, automotive, energy, nuclear fuel, crystal growth, and waste treatment products.
www.hcstarck.com
H.C. Starck, Newton, Mass., announces that it has joined the team at the Worcester Polytechnic Institute’s Center for Heat Treating Excellence, an alliance between the industrial sector and university researchers that addresses short- and long-term needs in the heat treating and thermal processing industry.
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Selective separation sintering enables 3D printed parts to be made of Martian materials
April 8, 2016
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The University of Southern California, Los Angeles, announces that a novel 3D-printing process called selective separation sintering has won the NASA competition for a technology that could enable space travelers to build structures of crushed basalt rock and regolith found on Mars.
Selective separation sintering (SSS) is a powder layer-based additive manufacturing approach. In the printing process, a dry powder of higher sintering temperature (S powder) is deposited into the base powder (B powder) of lower sintering temperature, outlining the shape of the part. When printing of all layers is completed, the material is sintered at the lower temperature, making a solid part that is easy to remove from the S powder. SSS can reportedly fabricate high-temperature ceramic and metallic parts at comparatively lower cost with high quality.
According to Prof. Behrokh Khoshnevis and his team, who won the NASA competition, the technology is suitable for building structures such as blast walls, hangars, radiation shields, and landing pads on the Moon and Mars. Preliminary results have proven the capability of SSS in successfully printing ceramic and metallic parts. Future experiments are planned for improving the process resolution.
The printing time in SSS, which is linearly proportional to the size of the part, becomes relatively shorter for larger parts. The S-powder in SSS is removed completely, hence no contamination remains on the part or on the sintering furnace. In addition, the cost of the SSS hardware is said to be a fraction of all other machines for additive manufacturing.
Details of the SSS process including diagrams are here: http://sffsymposium.engr.utexas.edu/sites/default/files/2015/2015-6-Zhang.pdf
www.usc.edu
The University of Southern California, Los Angeles, announces that a novel 3D-printing process called selective separation sintering has won the NASA competition for a technology that could enable space travelers to build structures of crushed basalt rock and regolith found on Mars.
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3D-printed metal aircraft parts
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Alcoa, Pittsburgh, entered into an agreement with Airbus, France, to supply 3D-printed metal parts for commercial aircraft. The parts will be produced using comprehensive capabilities—from multimaterial alloy development to additive manufacturing and aerospace parts qualification. The first additive manufactured parts are expected to be delivered midyear.
The agreement draws on Alcoa's aerospace experience and new technologies gained through its recent acquisition of RTI. The company also recently invested in 3D-printing and metallic powder production capabilities at its technical center outside of Pittsburgh.
Last year, Alcoa acquired RTI International Metals (RTI)—now known as Alcoa Titanium & Engineered Products (ATEP)—which grew its additive manufacturing capabilities to include 3D-printed titanium and specialty metals parts produced at ATEP's Austin, Texas facility. The Airbus agreement draws on these capabilities as well as ATEP's titanium ingot melting and billetizing, machining, finishing, and inspection technologies.
Alcoa will use advanced CT scan and hot isostatic pressing (HIP) capabilities at its advanced aerospace facility in Whitehall, Mich. HIP strengthens the metallic structures of traditional and additive manufactured parts made of titanium and nickel based superalloys. Through a $22 million investment in the technology, Alcoa today owns and operates one of the largest aerospace HIP technology complexes in the world.
Additionally, Alcoa is bolstering its additive manufacturing capabilities through a $60 million expansion in advanced 3D-printing materials and processes, including metallic powders. The expansion is located at the Alcoa Technical Center near Pittsburgh.
Alcoa, Pittsburgh, entered into an agreement with Airbus, France, to supply 3D-printed metal parts for commercial aircraft.
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Conveyor oven maximizes uniform adhesive cure on aluminum
April 5, 2016
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Wisconsin Oven Corp., East Troy, has shipped a natural-gas-fired three-zone curing conveyor oven to a leader in metal fabrication to cure a solvent-based adhesive that will be printed on a continuous corrugated aluminum web. The curing oven will be placed in a complete printing line, and is designed to handle a corrugated aluminum web 24 inches wide and 0.125-inch thick, weighing up to one pound per square foot or less. The adhesive deposition will be up to 300 mg/sq. ft. on the top surface only.
The curing oven has a maximum temperature rating of 300°F; the work chamber is 25 feet long, 2.3 feet wide, and six inches high. The chamber has three zones of heat control: each zone is 8 1/3 feet long.
Zone 3 may be used as a cool-down zone, with the recirculation and exhaust blower operating and the burner off. The belt conveyor oven utilizes a stainless steel flat flex belt for thermal efficiency. The recirculation system is configured with top-down airflow, which provides uniform heat distribution along the top of the aluminum web, and is optimal for an even cure of the applied adhesive.
"With this project, we wanted to make sure the oven design would maximize the uniformity of the cure," says Tom Trueman, Senior Application Engineer of Wisconsin Oven. "The three temperature zones and top-down airflow were the ideal solution, because the zones give the customer the flexibility to adjust the process for the best end result."
www.wisoven.com
Wisconsin Oven Corp., East Troy, has shipped a natural-gas-fired three-zone curing conveyor oven to a leader in metal fabrication to cure a solvent-based adhesive that will be printed on a continuous corrugated aluminum web.
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Continuous roller hearth system heat treats aluminum automotive castings
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Consolidated Engineering Company (CEC), Kennesaw, Ga., has received a purchase order for a continuous roller hearth T6 system with a water quench and age oven from an aluminum casting company in the United States. The system is designed for the heat treatment of cast aluminum knuckles and other automotive castings. The company is a rapidly growing foundry business that has been consistently winning automotive orders .
High pressure die casting, in which molten aluminum is injected into a metal die, now accounts for more than half of all aluminum castings worldwide. This manufacturing method has been shown to be particularly suitable for making complex parts for automobiles. These castings are often used as sheet or extrusion connectors to tie together portions of all-aluminum car spaceframes (chassis), which are finding broader application in high-end cars.
CEC manufactures solutionizing furnaces for all types of castings, forgings, extrusions and tubing, and has extensive experience in heat treating castings. To date, CEC's T4 & T6 installations process more than 57 million aluminum cylinder heads, engine blocks, and wheels every year. CEC has invented and developed solution heat-treatment machine innovations and processes that have generated more than 105 patents.
To develop and optimize processes, more than 6350 CEC sponsored or funded casting tests have been run to prove process innovations. The corporate focus is to save operating costs and pollution while improving product quality. CEC invented and remains the world leader in trayless and basketless head, block, and wheel casting processing.
www.cec-intl.com
Consolidated Engineering Company (CEC), Kennesaw, Ga., has received a purchase order for a continuous roller hearth T6 system with a water quench and age oven for the heat treatment of cast aluminum knuckles and other automotive castings.
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VertiQuench technology optimizes heat treatment for aluminum tubes
Source: ASM International
Seco Warwick, Meadville, Pa., exhibited its VertiQuench aluminum solution heat treatment furnaces and aging systems at Tube 2016 in Dusseldorf.
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One Minute Mentor: Tempering Temperature and Corrosion Properties
March 31, 2016
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One Minute Mentor: Tempering Temperature and Corrosion Properties
The graph shows the corrosion resistance of martensitic stainless steels with high hardness. It compares nitrogen alloyed grade (M340 = AISI 440Mod) with the standard grade AISI 440C.
For the application of higher tempering temperatures, corrosion properties also have to be taken into consideration. Usually the minimum in corrosion resistance can be found slightly above the secondary hardening maximum. In 17%-Cr high-carbon grades such as AISI 440C, corrosion resistance already starts to deteriorate at tempering temperatures higher than 390°F, as shown in the graph; lower-carbon grades like AISI 420, and even more the nitrogen-alloyed grades, show a significant drop in corrosion resistance only at tempering temperatures higher than approximately 840°F.
Volume 4D, Heat Treating of Irons and Steels -> Tool Steels -> Heat Treating of Mold Steels and Corrosion-Resistant Tool Steels -> Recommended Heat Treating Practices
The graph shows the corrosion resistance of martensitic stainless steels with high hardness. It compares nitrogen alloyed grade (M340 = AISI 440Mod) with the standard grade AISI 440C.
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Solar Manufacturing partners with Refrac Systems for GFQVHP system
March 30, 2016
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Refrac Systems, Chandler, Ariz., has contracted with Solar Manufacturing, Souderton, Pa., and Beckwood Press & Machinery/Triform, Saint Louis, to help design and build a large 100-ton-load gas fan quench vacuum hot press (GFQVHP) system for its aerospace diffusion bonding operation. Solar Manufacturing was selected due to its world class experience in the design and use of vacuum furnaces with gas fan quench cooling capabilities. The furnace chamber for this unit was built by Amity Industries, Douglassville, Pa. Beckwood Press & Machinery/Triform was selected to build the large 100 ton "Four Post" hydraulic press frame for the system. The control console unit was built by Optima Stantron, Lawrenceville, Ga.
Refrac Systems, working with Solar's engineering team, selected a derivative of the Solar Manufacturing standard HLF-5748-2IQ internally quenched 2-bar vacuum furnace as the base design of the system. The new system contains many new engineered designs as needed to be both an automated vacuum hot press, and to be extra versatile for making super plastically formed and diffusion bonded (SPFDB) aerospace structures.
Norm Hubele, President of Refrac Systems, states "Solar Manufacturing and Beckwood Press & Machinery are both industry leaders with robust engineering experience. We have worked closely together to design and build this one of a kind GFQVHP."
William Jones, CEO of the Solar Atmospheres family of companies, notes "Norm put together a team of engineers to design and build this furnace back in 2013. This state-of-the-art GFQVHP contains many innovations that will be discussed at a later time. Throughout the entire process, Norm has personally reviewed all aspects of the design and added considerable insight to the development of this unique vacuum furnace system."
Solar Manufacturing expects to ship the GFQVHP unit in July, and final assembly, testing and startup is projected for the 4th quarter 2016 in Chandler.
www.solarmfg.com
www.refrac.com
Refrac Systems, Chandler, Ariz., has contracted with Solar Manufacturing, Souderton, Pa., and Beckwood Press & Machinery/Triform, Saint Louis, to help design and build a large 100-ton-load gas fan quench vacuum hot press (GFQVHP) system for its aerospace diffusion bonding operation.
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Composite foams of steel spheres embedded in aluminum insulate against heat
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North Carolina State University, Raleigh, reports that novel lightweight composite metal foams made of materials such as steel spheres embedded in aluminum are more effective at insulating against heat than solid conventional metals such as steel. The composite metal foam consists of metallic hollow spheres — made of materials such as carbon steel, stainless steel or titanium — embedded in a metallic matrix made of steel, aluminum, or other metallic alloy. These foams are especially promising for storing and transporting nuclear material, hazardous materials, explosives, and other heat-sensitive materials, as well as for space exploration.
"We have developed two technologies for manufacturing composite metal foams (CMF)," says Afsaneh Rabiei, a professor of mechanical and aerospace engineering at NC State and corresponding author of a paper on the work. "One is based on casting a low melting point matrix material, such as aluminum, around hollow spheres made of a material with a higher melting point, such as steel. This creates aluminum-steel CMFs, for example. The other technique is based on sintering the matrix powder around prefabricated hollow spheres. This creates CMFs such as steel-steel, which consist of steel hollow spheres in a steel matrix."
In one test, researchers exposed samples of 2.5 by 2.5-inch steel-steel CMF that were 0.75 inches thick to a fire with an average flame temperature of 800°C for a period of 30 minutes on one side, and monitored the material to see how long it would take for the heat to reach the opposite side of the sample.
For a piece of bulk stainless steel with the same dimensions as the CMF sample, it took only four minutes to reach 800°C, but it took eight minutes for the steel-steel CMF to reach the same temperature.
"We already knew the CMFs have outstanding high-velocity impact resistance, and effective radiation shielding. Now we know that it can withstand high heat," Prof. Rabiei says.
The researchers also found that the composite metal foam made entirely of stainless steel expands 80% less than bulk stainless steel at 200°C — and the differential increases at higher temperatures. Another noteworthy advantage is that the composite metal foam expands at a fairly constant rate when exposed to high heat — whereas conventional bulk metals and alloys such as stainless steel expand more rapidly as temperature increases.
www.ncsu.edu
North Carolina State University, Raleigh, reports that novel lightweight composite metal foams made of materials such as steel spheres embedded in aluminum are more effective at insulating against heat than solid conventional metals such as steel.
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