A Troubleshooting Guide for Brazing Furnace Atmospheres

The atmosphere used in a brazing furnace plays a critical role in the final quality and metallurgical properties of the brazed component. Typically, exothermic, dissociated ammonia and nitrogen/hydrogen atmospheres are used for brazing mild steel, alloy steel and stainless steel components. The atmosphere composition, flow rates, pressures, and dew point are some of the key variables that can be controlled to control the final quality. In almost all brazing companies there can be quality issues that is a direct result of improper atmosphere application and control. Common problems include flashing, inadequate braze flow, oxidation, sooting, decarburization and carbon pick up. This troubleshooting presentation reviews years of field experience with nitrogen and hydrogen based atmosphere systems. It is prepared to help the heat treater or the brazing production engineer to identify these problems and apply appropriate corrective action. A systematic approach recommended analytical tools used in problem solving will also be presented.