AWS G2.1M-G2.1:2012 pdf download.Guide for the Joining of Wrought Nickel-Based Alloys
3. Terms and Definitions
AWS A3.0M/A30, Standard Welding Terms and Definitions, Including Terms for Adhesive Bonding, Brazing. Soldering,Thermal Cutting, and Thermal Spraying, provides the basis for terminology used herein. However, the following terms and definitions are included below to accommodate usage specific to this document.
solid solution strengthened nickel-based alloys. Single phase (i.e., homogenous alloy mixture with a single type of microstructure) nickel-based alloys with alloy additions not exceeding the limits of solubility. The most common alloy additions, either alone or in combination, are copper, chromium, molybdenum, and iron. Solid solution alloys can only be strengthened by cold working and not by heat treatment.
precipitation hardenable (strengthened) nickel-base alloys. Nickel-base alloys that can be strengthened by exposure to a certain temperature range long enough to cause very small phases (e.g.. small particles having a different chemical composition and structure than the surrounding material) to form and strengthen the matrix.
5.1.1 Descriptions of the Alloys and Typical Applications. The chemical composition limits of many of the com-mon solid solution strengthened nickel-based alloys are given in Table 1. Solid solution strengthening occurs when one or more elements (such as chromium) are added to another element (such as nickel) to form a homogenous composition.Alloying elements are added to nickel to strengthen the metal and to improve its corrosion resistance. Depending on the alloy, some of the primary alloying elements added to nickel for solid solution strengthening include chromium, molyb-denum, iron, cobalt, tungsten, and carbon. The material's structure, even after alloying, is homogenous.These solid solu-tion alloys cannot be strengthened by heat treatment and can only be further strengthened and hardened by cold working.
For example, quenching a solid solution nickel-base alloy from a high temperature will not harden the alloy- neither will heating the alloy at elevated temperatures. Precipitation-hardenable nickel-base alloys, however, can experience a dramatic increase in strength by heating (aging) in the 540°C- -815°C [1000*F-1500°F] range.
In addition to strengthening by the addition of solid solution alloying elements, the nickel-base“precipitation hardened" alloys are also strengthened by the inclusion of specific elements such as aluminum, titanium, and niobium. When appropriately heat treated, very small and discrete particles are produced and interspersed within the material's structure.The presence of these small particles (termed "“precipitates") can greatly increase the material's strength. These alloys are also able to be strengthened by cold working. The chemical composition limits of many of the common precipitation strengthened nickel-based alloys are given in Table 2. Precipitation strengthened nickel-based alloys is fully discussed in 6.1.AWS G2.1M-G2.1 pdf download.