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Neutral Hardening Atmosphere System

Meet stringent product quality specifications with a clean, reliable, low maintenance atmosphere system.

Air Products’ nitrogen-based neutral hardening atmosphere can economically replace unreliable, high maintenance generator atmosphere. When making parts that require high strength and toughness, heat treaters apply the neutral hardening process. The neutral hardening atmosphere must have sufficient carbon potential to avoid decarburization and be reducing enough to avoid surface oxidation. Air Products achieves this with a nitrogen-based atmosphere blended with a low concentration of hydrocarbons, such as propane or methane. With a precision gas blending system from Air Products, heat treaters can produce clean, consistent quality parts that meet their demanding specifications.

Neutral Hardening Atmosphere System

  • Highly reliable supply system
  • Safe, non-toxic atmosphere
  • Adjustable atmosphere composition to meet demanding specifications for multiple materials
  • Robust process monitoring and control with carbon probe and dewpoint analyzer
  • Cleaner atmosphere, resulting in reduced furnace maintenance cost
  • Quicker and easier start-up and shut-down to reduce non-productive time
  • Lower infrastructure investment and maintenance cost
  • Smaller floor area requirement

Ask the Expert

Liang He

Fémfeldolgozó K+F mérnök, Észak-Amerika

“Can I use ‘nitrogen+propane’ atmosphere for neutral hardening of steel parts?”

In neutral or quench hardening of steel parts, the furnace atmosphere plays a very important role to ensure the mechanical properties and surface quality. The atmosphere's carbon potential is matched to the treated part's carbon concentration, which allows the chemical composition of the steel surface to remain unchanged. Without adequate control of the atmosphere, unwanted chemical reactions like oxidation, decarburization or carburization can occur on the steel surface.

Air Products has successfully developed a ‘nitrogen+propane’ neutral hardening atmosphere with an advanced process control system. Propane reacts with residual or leaked oxygen in the furnace to generate an atmosphere with the desired carbon potential. The atmosphere control system meters the flowrate of nitrogen and propane based on the readings of oxygen and dew point sensors. This offering provides a more stable and consistent atmosphere composition and can be an economical alternative to traditional endogas or ‘nitrogen+methanol’ atmospheres by optimizing gas use while reducing equipment maintenance and safety-related costs.

Operation Analysis and Optimization

Our application engineers can work with your plant personnel to analyze and understand your entire process. Based on that analysis and your needs, they can recommend process improvement solutions that can help you enhance product quality and consistency, plus optimize gas use. Air Products services include leak-checking, furnace profiling, analytical calibration, gas analysis process troubleshooting and overall process review.

Learn more about our Neutral Hardening Atmosphere System.

Schedule a free consultation with one of our metals processing experts.