Thus, consideration in selecting an alloy also must be given the useful temperature range as might be limited by the Curie temperature. Uses of low-expansion alloys are divided into two general categories. First are those in which size change due to temperature variation must be minimized. These applications include structural components for measurement and control instruments in which excessive expansion and contraction due to temperature changes would seriously impair accuracy.
Typical applications include aircraft and missile control components, laser and optical systems and wave guide tubes. The second category includes temperature controls utilizing a bimetallic strip.
This simple type of control consists of a low expansion alloy metallurgically bonded to a high expansion alloy to produce a bimetallic element. When the strip is heated, the difference in thermal expansion rates between the two alloys causes the element to bend in curvature. The change in curvature is directly proportional to the difference in coefficient of expansion and the temperature change of the strip components, and inversely proportional to the thickness of the combined components.
The amount of bending is also affected by the ratio of the moduli of elasticity of the two components and by their thickness ratio. It has been used in applications such as radio and electronic devices where dimensional changes due to temperature must be minimal, for structural members in precision optical laser measuring devices and as the low expansion side in bimetal thermostats.
Two alloys in this family are suitable for unique low expansion requirements. This alloy has been used for aircraft controls and a variety of electronic devices. The second alloy - Carpenter Technology Super Invar "" alloy - is an iron-nickel-cobalt alloy which exhibits approximately one half the thermal expansivity of Carpenter Invar "36" alloy at or near room temperature. It has been used for structural components and supports for optical and laser instruments.
It is hopeful that this new specification will be available some time in Any one of four other low expansion alloys may be particularly suitable for service at higher temperature ranges.
It has been used for tunable capacitors and as the low expansion element in thermostat bimetal products. Both metals have been used in thermostats and thermoswitches. The thermal expansivity of the higher-nickel alloy approximates the thermal expansivity of some alumina ceramics over certain temperature ranges. The alloy in this family with the highest nickel content, Low Expansion "49" alloy, has been used for glass sealing of fiber optics.
For type analysis and typical properties of these low expansion alloys, see Fig. Expansion curves are plotted in Fig.
The low expansion alloys machine similar to, but not as good as a Type austenitic stainless steel. They are readily machinable, although they do produce gummy chips.
Therefore, large, sharp and rigidly supported tooling is recommended, with slower speeds. All of the alloys are very ductile, thus can be readily cold headed and formed. Stamping from cold rolled strip is easily accomplished. Parts may be deep drawn from properly annealed strip. Fabrication does add stresses which, unrelieved, can change the thermal expansion behavior.
For that reason, parts placed in service as fabricated may not meet design requirements. However, the nickel-irons will oxidize readily at these high temperatures. When annealing cannot be done in a non-oxidizing environment vacuum, dry hydrogen, dissociated ammonia, etc sufficient material must be allowed on work pieces to clean up by light grinding, pickling, etc.
One family of alloys possesses thermal expansion characteristics that are compatible with those of certain glass and ceramic materials. These specialty alloys are designed specifically to match the rate at which glasses and ceramics cool from various elevated temperature ranges.
This characteristic allows lasting metal-to-glass fusion in hermetically-sealed devices. As it cools, the glass sets. As cooling continues, it is very important that the glass and metal contraction behavior is similar below the glass strain point.
When there are excessive contraction differences between the materials being sealed, the stresses will cause glass breakage. Hermetic seals have been used for many years, with great success, to protect vacuum tubes from the environment, then transistors and more recently, semiconductors. With the evolution of the integrated circuit, these alloys have played a critical part in sealing the chip within the ceramic substrate. Alloys used for glass-to-metal seals tend to form a surface oxide which is readily "wetted", or chemically bonded to certain glasses.
This property, in all the iron-chromium and iron-nickel sealing alloys, assures high quality seals of good strength and hermeticity. It is general practice to pre-oxidize the metal parts in a special, controlled-atmosphere furnace before the actual glass sealing.
The use of ceramic-to-metal seals for all types of electronic devices has increased substantially. These seals often have consisted of a metallized alumina Al2O3 or beryllia BeO substrate brazed to a controlled expansion alloy member. High-performance alloys and powders for power generation, renewables, and Oil and Gas drilling and completions applications.
Corrosion, heat, and pressure resistant specialty alloys and stainless steels for valves, fittings, and fasteners. Titanium, stainless steel, and specialty alloys for surgical instruments, medical devices, prosthetics, and orthopedics. Carpenter Technology is leading innovation and excellence by leveraging our technical strengths, distinct products, and extraordinary process capabilities to provide you with value-added solutions that create breakthrough results.
We help customers like you solve the most extreme materials challenges. Our high-performance solutions are the critical component for tomorrow's successes, helping you achieve superior results in all your current and anticipated problems.
Learn more about our specialty alloys, formulated for superior performance in mission critical applications. We continue to push the latest advancements in materials science. Partnering with our customers, we apply a rich year history of expertise to meeting and exceeding their needs. We focus on redefining the limits of what is possible with ongoing alloy research and developments advancing emerging technologies such as additive manufacturing and magnetic stack lamination for electrification.
From deriving scale factors to staying on mass budget, we share our lessons learned and best practices. Our team of additive manufacturing experts produced this white paper with results supporting the key conclusion that these Ti64 powders for additive manufacturing are statistically equivalent along several quantitative measures, including oxygen level, contamination, density, flowability, and morphology.
The Carpenter Electrification team understands the need for tight tolerance laminations for challenging design criteria. Our branch of 3D printing experts, Carpenter Additive, reports on their study to create a systematic framework to optimize additive manufacturing for Nitinol, used in the medical market for its superior superelasticity and shape memory effect. Magnetic circuits in consumer electronic devices are one of the key constraints in miniaturization. Carpenter now calls themselves Carpenter Technology.
They have a search page for alloys: Alloy Name Search Some of the alloys named in their old book don't show up in the search. This is an informative page. You just type in a name, or alloy number, and it will give you the characteristics, how to heat treat, forging temperature and so on. The name I tried was 'Solar'. I then get a little black bar.
Thanks Art! Art Deco, I remember checking that book out of the local library whan I was in Junior high school. I was fascinated with the heat-quench proberties of steel. It was the only book I could find about tool steel.
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