Interfacial Quality Prediction Model for Al/Steel Sheets During Friction Stir Assisted Double-Sided Incremental Forming with Synchronous Bonding

Abstract

The widely investigated Al/steel laminated structures are challenged with subsequent plastic deformation due to the existence of interfacial brittle intermetallic compound layer. To overcome this drawback, a newly proposed thermomechanical forming technology as friction stir assisted double-sided incremental plastic forming with synchronous solid-state interfacial bonding is utilized to fabricate laminated structures, which can meet requirement of plastic deformation of laminates. Typical interfacial bonding performances produced by a series of experiments classified as sound bonding, de-bonding, over-thinning, penetration and crack are assessed. Local working peak temperature and maximum forming force in loading area are recorded and evaluated during stable bonding-forming stage. Considering heat-force coupling effect, a pressure-strain-temperature based prediction model is modified to assess process quality, which is conformed to experimental results. This work can help obtain proper process window to fabricate Al/steel laminated parts and shall also inspire to build guidance of related thermomechanical joining-with-forming processes to achieve high interfacial performance.