Heat Treatment Residual Moisture
Residual moisture in heat treatment is the remaining water content in furnace atmospheres or salt bath media, which can lead to surface reactions and hydrogen embrittlement. Continuous sensor monitoring is crucial.
Physical-Chemical Mechanism of Action
Residual moisture in furnace atmospheres or salt bath media consists of free water vapor that was not fully cooled and condensed. This humid air flow can lead to surface reactions with the metal, especially when the material is in a reducing environment. Additionally, moisture can cause hydrogen embrittlement, particularly in steels with high carbon content.
Metallurgical Relevance & Welding Risks
High residual moisture can lead to the following issues:
• Surface Reactions: The metal reacts with free hydrogen, causing corrosion and wear.
• Hydrogen Embrittlement: In steels with high carbon content, hydrogen can penetrate the crystal structure of the steel, leading to hydrogen embrittlement and possible cracking.
Workshop Practice & Action Instructions
To control and reduce residual moisture, the following measures should be taken:
• Sensor Monitoring: Install and continuously monitor moisture sensors in furnace atmospheres or salt bath media.
• Air Flow Regulation: Ensure good air flow design in the furnace or salt bath to remove free water vapor.
• Pressure Control: Keep the pressure in furnace atmospheres or salt bath media constant and under control to reduce moisture.
• Drying Agents: Use drying agents that absorb and remove water vapor.