Heat treatment processes require a precisely controlled atmosphere for a successful process.
These metal processes are often used to manufacture critical parts in special alloys for industries such asaerospace, automotive, petrochemical ornuclear power. Poor control of the furnace atmosphere can affect alloy quality, with financial and safety consequences.
How to ensure efficient heat treatment in a controlled atmosphere?
If the atmosphere in the heat treatment furnace is not controlled, the alloy can become contaminated. This can lead to a loss of strength and ductility, as well as an increase in brittleness. The microstructure of the alloy can also be affected, resulting in poor dimensional stability and reduced service life. In addition, uncontrolled atmospheres can cause corrosion and other forms of damage to the alloy.
In some cases, contamination can even cause the alloy to crack or break.
A controlled atmosphere is essential for efficient heat treatment. By preventing contamination, it ensures that the treated alloy retains its properties.
This is particularly important in theautomotive, chemical and nuclear energy industries, where the following conditions apply:
The absence of a controlled atmosphere can lead to chemical reactions on the surface of the metal assembly to be heat-treated, compromising its quality and performance and leading to rejected parts.
Such conditions result in financial losses, lost time and potentially dangerous repercussions for the customer who uses the part without detecting the weakness. In addition, a poorly controlled atmosphere can lead to a damaged furnace or, worse still, injured employees.
A controlled atmosphere heat treatment furnace provides an optimum environment for metal components during the heat treatment process.
By carefully controlling the composition and flow of the gas inside the furnace, precise temperature control and minimal oxidation or decarburisation is achieved.
The result is improved product quality and consistency, as well as increased production efficiency.
In order to ensure efficient heat treatment in a controlled atmosphere, it is important to carefully monitor and control the following parameters:
By carefully controlling these parameters, it is possible to achieve precise heat treatment in a controlled atmosphere, resulting in improved product quality and consistency.
The inert gases most commonly used in heat treatment processes are argon (Ar), helium (He) and nitrogen (N₂).
The degree to which an atmosphere can be called inert depends on factors such as the type of gas, its level of purity, the temperatures involved, and the material being processed.Depending on the gas or gas mixture used, the process will be dedicated to different heat treatment types: annealing, neutral hardening, tempering, nitriding, sintering or brazing.
Fuji Electric gas analysers are used to control the atmosphere in all these processes, with capabilities to measure fast and precisely ratios such as Ar/He, Ar/N₂, He/N₂, H₂/Ar or H₂/N₂.
The latter is required to control a hydrogen-rich atmosphere. This is implemented to reduce iron oxide to iron and decarburize steel. It also effectively aids in heat transfer and can react with any oxygen present.
The Fuji Electric solution for controlling the H₂/N₂ is a compact industrial cabinet incorporating:
Consider the following example:
Because the thermal conductivity is different among gas components, when there is a change in the concentration of the component under measurement, the thermal conductivity of the sample gas will change to affect the temperature of the platinum wire.
The analyser uses the temperature change to determine the gas concentration.
The furnace gas is continuously extracted by a heated and filtered sampling probe. It is then routed via a heated sampling line to the wall-mounted compact cabinet.
This integrates theanalyser thermal conductivity TCD and the entire sampling system specially designed to ensure the safety of theanalyser and guarantee accurate, representative and reliable measurement of H₂ concentration.
ApplicationDownload your application sheet and precisely control the furnace atmosphere during heat treatment!
