Invar Alloy 4J33 & 4J34
Invar alloy 4J33 and 4J34, also known as FeNi36, are two types of low coefficient of thermal expansion alloys. These alloys are made up of mainly iron and nickel, together with a small amount of molybdenum. The primary application of these alloys is in areas where a component needs to maintain a constant size despite changes in temperature.
These alloys are characterized by having an extremely low coefficient of thermal expansion for a wide range of temperatures. In fact, the thermal expansion of 4J33 and 4J34 is the smallest of all Fe-Ni alloys. This makes it ideal for applications such as glass-to-metal seals, timing mechanisms, and components in electronic devices. They also have high magnetic permeability which further enhances their usability.
The compositions of 4J33 and 4J34 are released by the China standard YB/T5234-1993. Both alloys contain balanced proportions of nickel and iron, with a small amount of molybdenum. In the case of 4J33, the composition ratio is 35.0-37.0% nickel, 58.0-63.0% iron, and 3.2-3.8% molybdenum. 4J34’s composition ratio is 35.0-37.0% nickel, 58.0-63.0% iron, and 0.5-1.5% molybdenum.
In addition to their low coefficients of thermal expansion and high magnetic permeability, Invar alloys 4J33 and 4J34 possess superior mechanical properties. They have excellent oxidation resistance and good corrosion resistance. They also have good wear resistance and excellent formability. As such, these alloys are well suited for precision engineering components and products in the fields of construction, aviation, and shipbuilding.
In terms of production, Invar alloys can be easily forged and cold worked. Generally, they can also be welded, however due to the risk of cracking, it is important to ensure the temperature gradient of the weld is not too great. At the same time, they can also be machined. It should be noted, however, that when machining these alloys, high cutting speeds and a good coolant should be used to avoid cracking or deformation.
In conclusion, Invar alloys 4J33 and 4J34 possess superior mechanical properties and are characterized by excellent formability and low thermal expansion. Due to these characteristics, these alloys are well suited for a wide range of precision engineering applications, in particular those which require components to maintain a constant size despite temperature changes. The compositions for both alloys can be found in the China standard YB/T5234-1993.
