Carbon steel components have been routinely annealed or heat treated in nitrogen-hydrogen atmospheres to relieve stress, alter microstructure and/or improve surface appearance for a number of years. The flow rate and composition of nitrogen-hydrogen atmosphere to be used for annealing components in furnaces are usually determined by a trial and error approach. Once the atmosphere flow rate and composition that produces parts with acceptable quality have been determined, they are generally fixed for future annealing operations. Although the composition of nitrogen-hydrogen atmosphere introduced into a furnace does not change with time, the true reducing or oxidizing potential of the atmosphere inside the furnace changes continuously with time due to leaks and drafts in the furnace, desorption of impurities such as moisture from the surface of components or decomposition of lubricant present on the surface of components being annealed. This continuous change in reducing or oxidizing potential of the atmosphere inside the furnace provides a great difficulty to commercial heat treaters and parts producers to produce annealed components with good and consistent quality and compete effectively in the global market. Therefore, to provide operational flexibility to commercial heat treaters and parts producers in terms of (1) controlling the true reducing or oxidizing potential of the atmosphere inside the furnace and (2) improving quality of annealed components, Air Products has developed an advanced control system currently being marketed under the trade name Purifire® AN.
Click here to find out more about Air Products' advanced control system (PDF, 79 K).
You will need the free Adobe Acrobat Reader to view these documents. |
|
