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Quenching and partitioning (Q&P) treatments result in promising mechanical properties of advanced high-strength steels. However, recent studies indicate that Q&P steels are very susceptible to hydrogen embrittlement (HE). Using slow strain-rate tests, the effects of hydrogen charging in different media without and with recombination poison were investigated for Fe-0.38C-1.92Si-0.66Mn-1.39Cr in quenched and tempered as well as Q&P conditions. In addition, corrosion tests and Zn electroplating of tensile specimens were performed. In both heat-treatment states, it was found that the intensified hydrogen-charging conditions using a recombination poison strongly impact the result of HE investigations: HE only occurs when a recombination poison is present. In addition, the negative influence of hydrogen formed during Zn electroplating can be limited by using proper electrolytes and electrical parameters. This allows keeping the HE susceptibility of the Q&P steel low in practical applications when recombination poisons are absent.

Due to a combination of different classes of materials, intrinsic hybrid composites are characterised by high strength and low weight. The mechanical properties of hybrid parts are mainly determined by the interface between the different materials. Consequently, this interface has to be considered in detail within the development of an intrinsic hybrid composite. The general approach of the considered composite is the combination of a mechanical form fit with adhesive bonding. This contribution focuses on the development, production and characterisation of the interface between aluminium and a fibre reinforced polymer as well as of the hybrid composite.

In this study, the electrodeposition of palladium alloys was investigated in a choline chloride/urea based deep eutectic solvent containing sulfosalicylic acid dihydrate as organic additive and Pd(II) + Ag(I), Pd(II) + Pt (II), or Pd(II) + Pt (II) + Ag(I) as metal components. The electrochemical behavior of the electrolytes was characterised by cyclic voltammetry. The electrodeposition processes require nucleation overpotential. Energy-dispersive X-ray data indicated that the layer thickness and composition of the produced Pd–Ag, Pd–Pt, and Pd–Pt–Ag films could be varied by changing the deposition mode. Additions of Ag(I) to the Pd and Pd–Pt electrolytes enhanced the overall metal deposition rate. Scanning electron micrographs of the electrodeposits showed that in general, the Pd alloys deposited by pulse current were nodular and relatively compact, whereas the films deposited by potentiostatic deposition were less dense and covered with dendrite-like and sharp-edged crystallites. Data collected from X-ray diffraction (XRD) experiments proved the existence of metallic alloys.

In recent years, the growing environmental awareness has led to the development of energy-efficient products, for example by the replacement of steel as construction material by aluminium to save weight and thus increase the energy-efficiency of mobile systems. However, to address the energy-efficiency of a product holistically, the energy consumption of the production process also has to be considered. For the anodic oxidation process of the AlMgSi1 aluminium alloy, the influence of the sulphuric acid concentration, the glycolic acid concentration, the electrolyte temperature and current density on coating thickness, hardness, ductility and wear resistance (scratch test), as well as on the consumption of electrical energy and process costs for the oxide coating formation are investigated using a design of experiments (DOE). An analysis of variance (ANOVA) is conducted to assess the significance of the parameters for the coating and process properties. For the considered range of the process parameters a significant enhancement of thickness, hardness and wear resistance of the coatings alters also energy consumption during anodic oxidation and process costs, which are assessed by material flow cost accounting (MFCA). Keywords: Anodic oxidation, Aluminium, Energy efficiency, Hardness, Ductility

Self-tapping aluminium screws are an innovative joining technology for the assembly of lightweight components in industrial scale. It has been established in the past that porous anodic oxide coatings in many cases reduce the fatigue strength of specimens without notches. In the present work, the fatigue behaviour of notched specimens, i.e. self-tapping screws made from aluminium alloys EN AW-6056, 6082 (both in a conventional state and in a fine-grained state produced by equal channel angular pressing – ECAP) and 7068 with and without oxide coatings is examined. The coatings are produced by hard anodising and are necessary for the thread-forming process during assembly. While the coatings do not affect the static tensile strength, they reduce the fatigue strength for the specimens of the 6056 and the 6082 alloy. For the 7068 alloy a slight increase in fatigue strength is discovered on a low load horizon. The scatter of endured fatigue cycles until fracture of specimens is generally reduced by the anodic oxide coatings.

The application of Al/Mg compound materials for lightweight structures is limited by their corrosion susceptibility. The primary corrosion attack takes place at the Mg component. This may partly be caused by galvanic corrosion and partly by the insufficient formation of a natural passive layer on magnesium. Therefore, oxide coatings were produced on the co-extruded Al/Mg compounds by simultaneous plasma electrolytic oxidation (PEO). A silicate-alkaline and a silicate-phosphate-alkaline electrolyte were used for the coincident production of coatings with a thickness of several 10 microns on both the aluminum and the magnesium component. The inherent flaws of the coating (pores, cavities) allow for the infiltration with an epoxy-based sealant. The electrochemical behavior of the magnesium component covered with the oxide coatings with and without sealing was compared with reference to the unmodified surface. The surface modification (PEO w/wo sealing) significantly decreases the corrosion susceptibility of the Mg component, and thus of the compound.

In the recent decades, various process windows have been found for plasma anodising of aluminium surfaces to produce wear-resistant alumina coatings. The coatings offer a high hardness and provide an excellent bonding to the substrate material, thus preventing spallation under mechanical or tribological load. In the present study, coatings with a high abrasive wear resistance and a hardness of up to 12 GPa were produced in an electrolyte of 5 g/l sodium metasilicate and 5 g/l potassium hydroxide at a current density of 30 A/dm2. To understand the reasons for the high wear resistance, the morphology as well as the phase composition and distribution within the coating were examined globally and locally using X-ray diffraction with conventional and grazing incidence and electron backscatter diffraction. The analyses show that the coating globally is comprised of approximately one third of α-alumina, one third of γ-alumina and one third of amorphous alumina with locally varying phase content.

Thermoplastic hybrid laminates are a novel class of material compounds that offer the possibility for large-scale production routes. The laminates consist of an assembly of fiber-reinforced semi-finished layers and metallic sheets in an alternating arrangement. Through the targeted combination of the individual sub-components, a high performing lightweight material with tailor-made properties is achieved. The paper focuses on an advanced thermoplastic hybrid laminate of the CAPAAL type, which is made up of continuous carbon fiber-reinforced polyamide sheets, aluminum top sheets and with continuous glass fiber-reinforced polyamide interlayers in between. The mechanical performance under quasi-static and 3-point bending fatigue, the corresponding damage as well as failure mechanisms are investigated. Under quasi-static bending, a comparatively high stiffness (52 GPa) and strength (645 MPa) in comparison to the commercially established thermosetting hybrid laminates were achieved while even at high strains no interfacial delamination was observed. The bending fatigue tests show that pure elastic loading of the laminate is below the fatigue limit and the laminate withstands one million load cycles without any measurable damages in the individual sub-components. Higher loads are leading to crack propagation inside the aluminum top sheet, whereas only the highest loads applied induced additional damage occurrence inside the thermoplastic matrix. For the first time, investigations on the mechanical performance of a CAPAAL type hybrid laminate under fatigue bending loads are presented. Hereby, in combination with the fast manufacturability of the laminate as a semi-finished product and its subsequent high formability, the suitability for e.g. automotive applications is demonstrated.

Thermally sprayed alumina coatings are widely used in a range of industrial applications to improve wear and erosion resistance, corrosion protection and thermal insulation of metallic surfaces. These properties are required for many components to be used for production processes in the paper and printing industry. Another appropriate method to produce ceramic coatings is the plasma electrolytic oxidation (PEO). However PEO can only be applied on self-passivating metals like aluminium, titanium, magnesium and their alloys. The present paper concerns a combination of cost-efficient arc spraying and flame spraying of Al coatings (Al99.5, AlCu4Mg1) on steel substrates and post-treatment by plasma-electrolytic oxidation (PEO). The microstructure and phase composition of generated oxide coatings are examined and discussed. The created Al 2 O 3 layers show outstanding hardness up to 1600 HV0.1, good bonding strength and excellent abrasion resistance compared to atmospheric plasma-sprayed Al 2 O 3 -coatings. The results show the superior performance of PEO-coatings and demonstrate their applicability for technical components in extreme operating conditions.