Showing papers by "Miroslav Karlík published in 2005"
TL;DR: In this paper, a twin roll cast AA6016 alloy sheet was pre-aged at 180°C for 2-10 min at the pre-aging stage and shown to have a sufficient bake hardening response.
Abstract: The bake hardening response of a twin roll cast Al–Mg–Si (aluminium alloy AA6016) sheet, submitted to pre-aging treatments at 180°C shortly after solutionising, has been investigated by means of tensile testing, microhardness and electrical conductivity measurement, differential scanning calorimetry and transmission electron microscopy. During pre-aging at 180°C, stable Guinier–Preston type 1 (GP1) zones form first and suppress any subsequent natural aging. Clusters and small GP1 zones are reverted, and stable β" nuclei are formed. These nuclei grow readily to become coherent β" particles during the paint bake cycle, giving a considerable increase in strength. A pre-aging treatment for 2–10 min at 180°C offers a sufficient bake hardening response for the twin roll cast 6016 alloy sheet.
28 citations
TL;DR: In this paper, the microstructure of a thin-cast (3 mm) Al-Fe-Mn-Si (AA8006) strip is compared with another strip of the same alloy cast at conventional gauge.
Abstract: The recent trend in Twin Roll Casting has been to reduce the casting gauge to less than 3 mm in order to reduce the processing costs, to take advantage of increasing rates of solidification and to increase productivity. Conventional casters typically cast strips 6 to 10 mm thick and operate at essentially constant production rates in this range. The new generation casters, on the other hand, are able to cast strips down to 1mm and offer a notable increase in the casting speed and thus in the caster productivity. It has been reported that the thin strips show some marked differences with respect to conventional strips owing to the temperature gradients and deformation involved in the thin-gauge casting process and may require different down stream processing cycles. The characterization of the thin strip structure is thus essential. This paper describes the microstructure of a thin-cast (3 mm) Al-Fe-Mn-Si (AA8006) strip in comparison with another strip of the same alloy cast at conventional gauge ...
11 citations
TL;DR: The mechanical properties of 15Ch2MFA steel were characterised by tensile and instrumented Charpy tests as discussed by the authors, showing that the fracture surfaces of Charpy specimens broken in the ductile-to-brittle transition temperature range contain a certain proportion of ductile fracture correlated to fracture energy.
9 citations
TL;DR: In this paper, the fracture properties of the hot rolled Fe-28Al intermetallic alloy with the addition of chromium and cerium were studied and the fracture toughness and the fatigue crack growth rate (da/dN−ΔK curves) were measured.
8 citations
TL;DR: In this article, the effect of composition and down-stream processing on sheet properties should be well understood in order to produce high quality products, which exhibit good formability and high strength Finegrained microstructure and well-balanced texture are the necessary pre-requisites.
Abstract: Inner panels of modern ecological cars are nowadays manufactured from Al-Mg alloys Continuously twin-roll cast sheets are a cost effective substitution for direct-chill cast sheets The effect of composition and down-stream processing on sheet properties should be well understood in order to produce high quality products, which exhibit good formability and high strength Finegrained microstructure and well-balanced texture are the necessary pre-requisites Results of the investigation of twin-roll cast AlMg2Mn08 and AlMg3 alloys are reported Sheets of 10 mm gauge were prepared using different processing routes The route involving homogenisation results in grain coarsening and anisotropy, however, deep-drawing ability is affected only a little
2 citations