Abstract
Within the framework of the Collaborative Research Center 1153, we investigated novel process chains for the production of bulk components with different metals as joining partners. In the present study, the co-extrusion of coaxially reinforced hollow profiles was employed to manufacture semi-finished products for a subsequent die-forging process, which was then used for the manufacture of hybrid bearing bushings. The hybrid hollow profiles, made of the aluminum alloy EN AW-6082 paired with either the case-hardening steel 20MnCr5, the stainless steel X5CrNi18-10, or the rolling bearing steel 100Cr6, were produced by Lateral Angular Co-Extrusion. Push-out tests on hybrid hollow sections over the entire sample cross-section showed shear strengths of 44 MPa ± 8 MPa (100Cr6) up to 63 MPa ± 5 MPa (X5CrNi18-10). In particular, the influence of force and form closure on the joint zone could be determined using specimen segments tested in shear compression. Locally, shear strengths of up to 131 MPa (X5CrNi18-10) were demonstrated in the shear compression test. From these samples, lamellae for microstructural analysis were prepared with a Focused Ion Beam. Detailed analyses showed that for all material combinations, a material bond in the form of an ultra-thin intermetallic phase seam with a thickness of up to 50 nm could be established.
Highlights
Accepted: 16 February 2022Over recent decades, efforts have been made to realize lightweight construction concepts by combining different materials
A higher ram speed was selected for initial filling of the tool compared to the actual extrusion process in order to counteract the cooling of the tool
Compared with previous hybrid profiles made of EN AW-6082 and 20MnCr5, the current compression tests showed a slightly higher level of average shear strength for the hollow sections produced by Lateral Angular Co-Extrusion (LACE), with an average of 63 MPa ± 5 MPa over the entire profile length
Summary
Accepted: 16 February 2022Over recent decades, efforts have been made to realize lightweight construction concepts by combining different materials. The material combination of aluminum and steel, the most commonly used metallic construction materials, is notably promising for advanced lightweight construction applications [1]. In order to meet local component requirements, various process chains for the manufacture of hybrid components for bulk metal forming are being researched as part of the Collaborative Research Center (CRC). These include the production of hybrid bearing bushings with wear-resistant steel on the bearing surfaces and a significantly reduced mass through the use of aluminum for the rest of the component. In the first manufacturing step, the different materials for the hybrid bearing bushing are joined to semi-finished products by means of co-extrusion. These semis are forged into bearing bushings, and the joint zone established through co-extrusion undergoes a thermo-mechanical treatment. The process chain developed has been described in more detail in a previous publication [2]
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