Inconel 625

Alloy 625 belongs to the nickel alloy family, with nickel-chromium as the main component, and is widely used in demanding applications such as oil and gas. It has excellent corrosion resistance at both room and elevated temperatures, forms a protective film that prevents further oxidation, and maintains its mechanical properties over a wide temperature range. It is better known by the trade name Inconel from Special Metals.
Developed in the 1960s, Inconel 625 achieves considerable strength by adding molybdenum and niobium to a nickel-chromium matrix. This gives the alloy solid solution strengthening properties, meaning that no additional heat treatment stages are required. It is stable up to 650°C with little loss of mechanical properties, and in fact retains most of its strength up to 800°C and even down to cryogenic temperatures.

Inconel 625 alloy still has excellent corrosion resistance in the harshest environments, especially against pitting and crevice corrosion, with a pitting resistance equivalent value (PREN) of over 45. This is due to its high content of chromium and molybdenum.

Inconel 625 is well suited for high temperature applications because most other metals are either brittle or oxidize easily at high temperatures. However, nickel-based alloys quickly form a protective oxide layer when heated in an oxygen-containing environment, which prevents further oxidation. In addition, it also has a relatively high melting point. This means that only a few special alloys can surpass the performance of nickel-based alloys at high temperatures.

Inconel 625 alloy is widely used in wellhead components, downhole equipment in corrosive/sour environments, and chemical process equipment due to its excellent corrosion resistance. It is also used in reactor core and control rod components in nuclear energy production, and occasionally in ship shafts and fasteners. In addition to its excellent corrosion resistance, Inconel 625 is also non-magnetic and spark-resistant. These physical properties are very useful in applications such as downhole equipment and tools for oil and gas exploration. Because its microstructure is actually austenitic, it is fairly simple to manufacture and process with the right tools and configurations.

Inconel 725 (Alloy 725, UNS N07725) can be specified for applications where the properties of Inconel 625 are desirable but the mechanical properties are insufficient. Controlled additions of titanium to Inconel 625 combined with further heat treatment can increase its strength by 2-3 times. This precipitation treatment state is also known as precipitation strengthening, age hardening, or aging. The goal is to form very fine precipitates that are widely dispersed throughout the bar. These precipitates "anchor" microstructural features (grain boundaries) and restrict movement when the metal is subjected to external loads.

Gnee Steel stocks 625 alloy solid bar in diameters ranging from 1/2" (12.7 mm) to 10" (254 mm). Our stock is certified to API 6A CRA and NACE MR0175 / ISO 15156-3.

Alloy 625 also complies with the following standards: NiCr22Mo9Nb, BS 3076 NA21, Werkstoff 2.4856, UNS N06625 and ASTM B564/B466.