Properties of nickel alloys pdf

Nickel-chromium-iron alloys combine these elements to produce alloys that resist oxidation and high-temperature corrosion. These alloys generally are also valued for their optimum creep and rupture properties at high temperatures. The high concentration of iron has led to the reclassification of these alloys as stainless steel.

With similar applications to nickel-molybdenum alloys, nickel-chromium-molybdenum alloys also provide high corrosion resistance especially with regard to reducing acids such as hydrochloric acid and sulfuric acid. This alloy is used in pollution control stack liners, ducts, and scrubbers, as well as in chemical processing components such as heat exchangers, evaporators, or reaction vessels.

These alloys of nickel add chromium and molybdenum to add creep rupture strength to the alloy. Applications for these alloys include industrial furnace components, gas turbines, catalyst grid supports to produce nitric acid, and fossil fuel production facilities. Nickel-titanium alloys feature shape retention of shape memory properties. By forming a shape from this alloy at a higher temperature and them deforming it from that formed shape at a lower temperature, the alloy will remember the initial shape and reform to that shape once heated to this so-called transition temperature.

By controlling the composition of the alloy, the transition temperature can be altered. Because dislocation creep and diffusional creep are indepen- Replacing the power-law Eq. This is done in Fig. As expected, dislocation creep dominates at high stresses and The 3. Creep tests performed on Ni— Introducing power-law creep parameters from Ni—Cr bulk data, but the creep bending model significantly over-predicts alloys of similar composition into two analytical creep the data.

A similar situation was reported for the power-law foam equations based on struts deforming by bending creep behavior of NiAl, Ni—Al, and Ni—Cr—Al reticulated or compression by dislocation creep provides predic- foams [5,14] created by pack-cementation from the same Ni tions which bracket the experimental creep data for the foams.

The relatively small grain size of the Ni—Cr foam struts of their creep behavior. Foams with many struts converg- indicates that diffusional creep may be dominant at low ing into nodes will deform primarily by strut compressive stresses. The above two equations are modified to incor- deformation, and their creep behavior will be more closely porate the contribution of diffusional creep. The experi- approximated by Eqs. Further and grain size all result in a distribution of strain rates within experiments at lower stresses will be needed to probe the the foam, for which only the volume-averaged rate is mea- validity of the foam diffusional creep equations.

More complex finite-element models are needed to quantify these variations, but the idealized foam creep equations Eqs. The authors thank Dr. Malka now at the University of Southern California for ex- The foam creep equations based on strut compressive defor- perimental assistance with oxidation measurements. To confirm the validity of the diffusional creep equations Eqs. Gibson, M. Ashby, Cellular Solids: Structure and Properties, grain size are needed to access a regime where diffusional Pergamon Press, Oxford, Degischer, B.

Ashby, T. Evans, N. Fleck, J. Hutchinson, H. Wadley, 5. Reticulated Ni—Cr foams with 9—32 wt. Andrews, J. Huang, L. Gibson, Acta Mater. Hodge, D. Dunand, Metall. Andrews, L. Ashby, Acta Mater. Their mechanical and oxidative properties were Zhang, M. Haag, O. Kraft, A. Wanner, E. Arzt, Philos. At ambient temperature, the foam compressive yield stress [8] D. Queheillalt, D. Hass, C. Sypeck, H. Wadley, J. Queheillalt, Y. Katsumura, H.

Wadley, Scripta Mater. The data are in general Bram, C. Stiller, H. Buchkremer, D. Baur, Adv. The oxidation kinetics of the foam is similar to those of the [11] D. Sypeck, P. Parrish, H. Hayden, in: D. Ultimate tensile strengths vary from 50 MPa for an aluminum to as high as MPa for very high-strength steels. Yield strength of of constantan — 45NiCu depends greatly on the heat treatment procedure, but for annealed alloy is about MPa.

Yield strength of superalloy — Inconel depends on heat treatment process, but it is about MPa. The yield point is the point on a stress-strain curve that indicates the limit of elastic behavior and the beginning plastic behavior. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed.

Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible. Some steels and other materials exhibit a behaviour termed a yield point phenomenon. Yield strengths vary from 35 MPa for a low-strength aluminum to greater than MPa for very high-strength steels.

Up to a limiting stress, a body will be able to recover its dimensions on removal of the load. The applied stresses cause the atoms in a crystal to move from their equilibrium position. All the atoms are displaced the same amount and still maintain their relative geometry.

When the stresses are removed, all the atoms return to their original positions and no permanent deformation occurs. Brinell hardness of superalloy — Inconel depends on heat treatment process, but it is approximately MPa. Rockwell hardness test is one of the most common indentation hardness tests, that has been developed for hardness testing. In contrast to Brinell test, the Rockwell tester measures the depth of penetration of an indenter under a large load major load compared to the penetration made by a preload minor load.

The minor load establishes the zero position. The major load is applied, then removed while still maintaining the minor load. The difference between depth of penetration before and after application of the major load is used to calculate the Rockwell hardness number. That is, the penetration depth and hardness are inversely proportional.

The chief advantage of Rockwell hardness is its ability to display hardness values directly. Thermal properties of materials refer to the response of materials to changes in their temperature and to the application of heat.

As a solid absorbs energy in the form of heat, its temperature rises and its dimensions increase. But different materials react to the application of heat differently. Heat capacity , thermal expansion , and thermal conductivity are properties that are often critical in the practical use of solids.

In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium. Some nickel alloys are strongly magnetic, others are virtually nonmagnetic; some have low rates of thermal expansion, others have high rates; some have high electrical resistivities; some have practically constant moduli of elasticity; one has an "elastic" memory.

In addition, nickel is magnetostrictive. With this wide range of characteristics, it is not surprising that there are several thousand alloys containing nickel.

It is impossible to consider all of these compositions in this publication and, therefore, several alloys in each of a number of categories have been selected to indicate the properties to be expected of the group.

Low-alloy and constructional nickel-containing steels have been excluded on two grounds. To do them justice would require excessive space and, in addition, their applications differ generally from these of the materials under discussion. On the other hand, nickel-containing stainkss steels have been included because many of their applications fall into the same areas as those of a number of the high-nickel alloys.