The last decade has seen double-digit growth in the use of vacuum heat treating and increased vacuum market share (Figs. 1-5) throughout the Americas. Vacuum processing is growing more than any other technology, due in large part to the demand for high quality, precision and repeatability of part performance in ever more sophisticated and demanding service applications. Each of the common vacuum processes will be discussed in this and future articles in this series.
Annealing
Annealing treatments are undertaken primarily to soften a material, to relieve internal stresses and/or to modify the grain structure. These operations are carried out by heating to the required temperature and soaking at this temperature for sufficient time to allow the material to stabilize, usually followed by a slow cooling at a predetermined rate. The choice of vacuum annealing is primarily influenced by the cleanliness and high quality of surface finish (Fig. 6) that can be obtained relatively easily compared to controlled-atmosphere heat-treatment operations.
Copper and Copper Alloys
Annealing of copper alloys is normally performed to soften the material after work (strain) hardening and to retain bright surface finishes. By Daniel Herring.
Vacuum thermal processing is key for aerospace component manufacturers due to industry demands for the highest possible quality. Brazing and surface treatment are two process areas where vacuum technology is utilized by the aerospace industry. The volume of work produced by vacuum brazing far exceeds that of any other process in which vacuum furnaces are being utilized. The transportation (automotive and aerospace) industry has provided the impetus for the increasing use of vacuum furnaces for brazing, and the use of lightweight, high-strength materials have also contributed to the popularity of brazing. Part two of this series continues our discussion of vacuum heat-treating processes and applications. By Daniel Herring
Electric heating elements in the form of coil, ribbon or rod made from alloys such as nickel-chromium, iron-chromium-aluminum and refractory metals are widely used throughout the heat-treating industry. They are found in both low- and high-temperature furnaces and perform well in cyclic-duty service. The temperature of a heating element and its surroundings is primarily dependent on the rate at which energy is being supplied and the rate at which it is able to transfer this energy – in the form of heat – to its surroundings. There is a critical rate of heat exchange, reflected in a design value called the watt-density, measured in watts/in2. Ideally, the power being generated is only slightly greater than the heat-transfer rate demanded by the load. By Daniel Herring
The present work studies the sintering and hardening response of the prealloyed steel powder Anchorsteel® 737 SH with added copper and carbon. Referred to as SH737 throughout, the finding of particular interest is the energy-saving process of sinter hardening. In recent years, powder metallurgical (P/M) components are increasingly being utilized for automotive and structural applications.[1] As compared to conventional casting techniques, P/M processing offers advantages such as lower processing temperature, near-net shaping, high final density, greater material utilization (>95%) and a more refined microstructure that provides superior material properties.[2] In addition, P/M products have greater microstructural homogeneity. by S. Anand, A. Raja, V.M. Shingade, A. Upadhyaya
Ever since JRD Tata received the first pilot license issued in India in 1929 and the launch of Tata Airlines three years later, the country has continued its dedication to the field. India even has its own air show – Aero India Show – which began in 1996 and now attracts around 380 exhibitors from more than 20 countries. As in the United States, Nadcap special-process audits – including heat treatment – are becoming a part of manufacturing life in India. By Performance Review Institute
With the advent of Nadcap and AMS 2750D compliance being placed upon them by their customers, companies using vacuum heating and brazing equipment for aerospace applications will be asking themselves whether it is more cost-effective to upgrade an existing system or to perhaps replace it with a new one. A number of factors should be considered before making the upgrade or replace decision. There are both “up-front” costs and operating costs that need to be evaluated. Five main areas of the typical vacuum heating or brazing system (Fig. 1) need to be reviewed to make a proper determination whether to upgrade or replace an existing system. By Matt Orfe
Many engineers think it is pretty easy to distinguish a ductile from a brittle crack. However, many people have incomplete understandings of these concepts. Look at the following two pictures of a broken steel tensile test coupon and a broken bolt. Figure 1 shows a necked down area right around the crack. This is a sure sign of a ductile fracture. Figure 2 shows a crack which followed the thread root, but did not have any readily observable change in shape. Hence, it is an obvious brittle crack.
Many people think that necking or visible deformation of the part means it is a ductile crack, and lack of such readily visible deformation means it is a brittle crack. But this is not necessarily the case. Let’s look at some trickier parts. The chain link in Figure 3 used to have a symmetrical shape and be a continuous flattened loop. But now there is a crack, and the shape has obviously changed from the as-manufactured symmetry. So this is a ductile crack, right? by Debbie Aliya
Electric heating elements in the form of coil, ribbon or rod made from alloys such as nickel-chromium, iron-chromium-aluminum and refractory metals are widely used throughout the heat-treating industry. They are found in both low- and high-temperature furnaces and perform well in cyclic-duty service. The temperature of a heating element and its surroundings is primarily dependent on the rate at which energy is being supplied and the rate at which it is able to transfer this energy – in the form of heat – to its surroundings. There is a critical rate of heat exchange, reflected in a design value called the watt-density, measured in watts/in2. Ideally, the power being generated is only slightly greater than the heat-transfer rate demanded by the load. By Daniel Herring
The present work studies the sintering and hardening response of the prealloyed steel powder Anchorsteel® 737 SH with added copper and carbon. Referred to as SH737 throughout, the finding of particular interest is the energy-saving process of sinter hardening. In recent years, powder metallurgical (P/M) components are increasingly being utilized for automotive and structural applications.[1] As compared to conventional casting techniques, P/M processing offers advantages such as lower processing temperature, near-net shaping, high final density, greater material utilization (>95%) and a more refined microstructure that provides superior material properties.[2] In addition, P/M products have greater microstructural homogeneity. by S. Anand, A. Raja, V.M. Shingade, A. Upadhyaya
Ever since JRD Tata received the first pilot license issued in India in 1929 and the launch of Tata Airlines three years later, the country has continued its dedication to the field. India even has its own air show – Aero India Show – which began in 1996 and now attracts around 380 exhibitors from more than 20 countries. As in the United States, Nadcap special-process audits – including heat treatment – are becoming a part of manufacturing life in India. By Performance Review Institute
With the advent of Nadcap and AMS 2750D compliance being placed upon them by their customers, companies using vacuum heating and brazing equipment for aerospace applications will be asking themselves whether it is more cost-effective to upgrade an existing system or to perhaps replace it with a new one. A number of factors should be considered before making the upgrade or replace decision. There are both “up-front” costs and operating costs that need to be evaluated. Five main areas of the typical vacuum heating or brazing system (Fig. 1) need to be reviewed to make a proper determination whether to upgrade or replace an existing system. By Matt Orfe
Many engineers think it is pretty easy to distinguish a ductile from a brittle crack. However, many people have incomplete understandings of these concepts. Look at the following two pictures of a broken steel tensile test coupon and a broken bolt. Figure 1 shows a necked down area right around the crack. This is a sure sign of a ductile fracture. Figure 2 shows a crack which followed the thread root, but did not have any readily observable change in shape. Hence, it is an obvious brittle crack.