Interface Microstructure and Thermal Expansion Mismatch in Alloy N/316H Bimetallic Plates

Two Alloy N/316H bimetallic plates have been fabricated by explosive welding and rolling technologies respectively. Metallographic observations indicate that the rolled bimetallic plate has a straight bond interface, in which some cavities and precipitates exist. While the explosive welded plate shows a wavy bond interfaces. The interface thermal expansion mismatch between the two alloys were evaluated in the two plates at high temperature. Results show that the thermal expansion coefficient of 316H is larger than that of Alloy N. The thermal expansion coefficient of the substrate plates depends on the thickness ratio between Alloy N and 316H, which reaches the maximum when the ratio is 1:4.