Microstructures and Deep-Drawing Properties of Copper–Steel Bimetallic Sheets Fabricated Using an Arc Spray-Rolling Short Process

Abstract

Annealing and rolling play critical roles in improving the mechanical properties of arc spraying coatings. In this work, we successfully fabricated copper–steel bimetallic sheets (CSBSs) using an arc spray-rolling short process and achieved excellent internal bonding of the copper coating and improved deep-drawing of the CSBSs via annealing and rolling synergistic treatment. The results indicate that the microstructure of the copper coating became dense, and the porosity effectively reduced after annealing–rolling–annealing (ARA) treatment. Tight bonding was also observed between the copper coating and steel substrate. The copper coating had a porosity of less than 0.2%, an average grain size of 3.8 μm, and a micro-hardness of 55 HV0.05. After tensile testing, the As-sprayed coating generated brittle fractures and delamination. The A-R-A coating also displayed elongated dimples, with the majority oriented along the TD direction, and bonded well with the steel substrate. In addition, the As-sprayed coating fell off directly after deep drawing. In contrast, the A-R-A coating did not exhibit cracks and fall off. The fracture mechanism gradually changed from falling off and cracking, to toughness deformation due to the reduced porosity and tighter grain boundaries, and finally to cooperative deformation due to the metallurgical bonding of the sprayed particles and good interface bonding properties. These findings provide guidance and reference for the practical application of thermal spray additive manufacturing.

Keywords

• thermal spraying
• coating
• annealing
• cold-rolled
• deep-drawing