• Behrens, Bernd-Arno
• Pape, Florian
• Poll, Gerhard
• Matthias, Tim
• Coors, Timm

Abstract

<p>A future trend for machine components such as rolling element bearings is the application of multimaterials for manufacturing. In order to manufacture such components with appropriate quality, a new process chain called Tailored Forming was set up. Within this process chain, joined semifinished workpieces are utilized and formed, followed by a finishing process including heat treatment. Thus, a high-strength steel is joined with a metallic base material such as mild steel or aluminum. In case of a Tailored Forming process, various process steps for joining different materials and a subsequent forming are investigated. This requires high production quality as the production steps build on one another and, in particular, the joining process can significantly influence the component's properties. This is dependent on pores, blowholes, or delamination of the different materials as well as the intermetallic phases existing between steel and aluminum during the joining process. Since the semifinished workpieces go through further process steps, their testing must be nondestructive. Such a test methodology can be realized by scanning acoustic microscopy. The method allows for a tomographic representation of material defects in multimaterial components to enhance the production processes. Typically, ultrasound image examinations are being used in the medical technology. The transfer of this technique to applications with inorganic and, in particular, metallic samples is still associated with great challenges. Metallic components exhibit high velocities and small differences of the ultrasonic signal, which represents a challenge for the digital scanning of ultrasonic measurements for these components. The measurements were performed using a PVA-TePla system with water as the coupling medium. In the case of Tailored Formed bearings, it is possible to evaluate the joining zone regarding defects and pores. This article presents the findings of such evaluations for bearing washers manufactured by plasma welding with a subsequent forming process and impact extruded shafts.</p>

Topics

• impedance spectroscopy
• pore
• phase
• aluminium
• strength
• steel
• ultrasonic
• forming
• intermetallic
• joining
• microscopy