Dissolution wetting of liquid copper on steel substrate - phenomena occurring during liquid-solid interaction

The present study is focused on the detailed characterization of morphology, microstructure, chemical and phase analysis of the Cu/steel interface zone obtained as a result of the wetting tests using the sessile drop method. The methodology involved contact heating of a copper piece placed on a highly deformed steel substrate at 1130 degrees C in an argon atmosphere. The experiment was supported with molecular dynamics simulations on early stages of Cu/Fe contact at high temperature. Plastic deformation of a P265GH steel substrate was caused by the explosive welding, which took place prior to the wetting. The experiments revealed that after 40 s, the wetting angle reached a value of 10 degrees, which did not change until the end of the test. This confirms the very good and fast wetting of the steel substrate by liquid copper. Atomistic simulations stay in agreement with the experiment revealing very rapid wetting. Microstructural observations of the Cu/steel couples using electron microscopy techniques showed a high-quality interface, without any voids or cracks. After the wetting experiment, the weighted average of ferrite grain size of the steel substrate (38 mu m) did not change. The microscopy observations indicated that the copper diffused into the substrate along the grain boundaries of the steel, causing the Fe-based grains to separate and move towards the copper drop area. This all confirmed that the effective and fast dissolution wetting mechanism takes place during liquid Cu-steel interaction.