ブレーズ法により接合した高クロム鋳鉄と鋼の接合強さに及ぼす接合条件の影響

概要

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Eutectic high chromium cast iron containing 26 % Cr and mild steel were brazed with pure copper filler, and relationships between bonding strength and bonding conditions were investigated. When the assembly of cast iron and steel having copper filler of 18, 35 and 50 μm in thickness was held at 1383 K to 1453 K for 0.6 to 3.6 ks in vacuum of 1.33×10-2 Pa, bonding strength (τB) increased with an increase in both bonding temperature and holding time, and decreased after reaching to a maximum value. Under the same bonding condition, τB lowered as the thickness of filler metal increased. In most of the samples, fracture occurs at different places in the bonded zone. It is considered that bonding strength depends on the microstructure of the bonded zone. On the other hand, rod-like-crystals grew from cast iron to steel in the bonding region. The ratio of the crystal length to the width of bonded zone(GA)increased with an increase in both bonding temperature and holding time, and increased as filler metal thickness decreased. These phenomena fairly correspond with the above mentioned relationships between τB and bonding conditions and filler metal thickness. Therefore, it is found that τB is closely related to GA. Further, it can be said that the decrease in τB may be due to a formation of voids in the bonded zone.
Japan Foundry Engineering Societyの論文