Melt base metal. Or just filler. Very different.

Welded joint has continuous metallurgical bond — essentially same material as base metal. Brazed joint has filler alloy bond between base metals — the filler is different from base, typically lower strength. Brazed joint strength is filler strength (often 30-70% of base metal). For critical structural, welding needed. For assemblies where joint loading is manageable, brazing is adequate.

Brazing excels at dissimilar metals — copper to steel, stainless to aluminum, ceramic to metal. Filler alloy bridges the metallurgical incompatibility. Welding dissimilar metals creates intermetallic compounds at interface — often brittle. Possible with specific filler alloys and techniques but difficult. For most dissimilar joining, brazing is the right answer.

Silver brazing alloys: silver + copper + other metals. Lower melting (600-800°C), cleaner joints, higher cost. Standard for precision work, jewelry, food equipment. Copper brazing: copper or copper-phosphorus filler. Higher melting (700-900°C), cheaper, good for steel-to-steel. Standard for HVAC piping, automotive, general industrial. Specific alloy choice depends on base metals and application.

Furnace brazing in vacuum or inert atmosphere (hydrogen, argon): prevents oxidation during heating, produces cleaner joints, higher quality. Standard for aerospace, medical, high-reliability applications. Alternative: torch brazing with flux to dissolve oxides. Flux works but leaves residue requiring cleaning. For best quality, controlled atmosphere brazing.

Joint gap matters for brazing — capillary action requires 0.05-0.2 mm gap. Too tight: filler can't flow in. Too loose: filler won't fill gap. Design fixtures to maintain gap during heating. Common joints: lap joint (overlap area, good strength), butt joint (limited area, weak), scarf joint (angled mating for strength). Our brazing work includes joint design review during DFM.

For simple single joints: welding typically cheaper per joint. For complex assemblies with many joints: brazing often economical because multiple joints complete simultaneously in furnace. For dissimilar metals: brazing essentially required. For production quantities, brazing allows automation (fixturing, furnace processing). Trade-off based on geometry, volume, material combinations.