In this contribution the precipitation and transformation processes at various aging times in the temperature range 873 – 1573 K were studied. The precipitation of the sigma phase was observed after just 3 min of aging, and after 30 min of aging at around 1053 K its fraction exceeded 40 %. An intensive austenite-to-ferrite transformation was observed above 1423 K. Optical microscopy, EDS, EBSD, XRD as well as micro-indentation hardness, hardness, impact toughness and tensile tests were carried out in order to evaluate the obtained microstructures of aged samples.
COBISS.SI-ID: 1039199
The hot-deformation behavior of as-cast 30Cr10Ni duplex stainless steel was investigated with the aim to better understand the conditions that lead to the occurrence of cracking. The results indicate that in the temperature range 1423-1523 K the as-cast microstructure exhibits increased workability, while below this temperature the microstructure is prone to cracking. As such, the as-cast microstructure should be crushed in the high-temperature range in order to avoid the occurrence of cracking.
COBISS.SI-ID: 1057375
The hot-deformation behavior of 1.17C–11.3Cr–1.48V–2.24W–1.35Mo tool steel was studied. Hot-compression tests were carried out. A procedure for determining an appropriate soaking temperature, which enables an extension of the safe hot-working range, was developed. A study of the dissolution of ledeburitic carbides showed that there is a limit fraction to which the carbides could be dissolved prior to hot working without any negative influence on the hot workability. A revision of the general opinion about the influence of non-dissolved carbides on the hot workability is given.
COBISS.SI-ID: 1091167
This article is concerned with the finite element implementation of an elasto-visco-plastic constitutive model using a symbolic approach. The numerical examples derived for polyethylene terephthalate (PET) polymers demonstrate that symbolic systems can be applied to develop complex constitutive models capable of simulating material responses that are in good agreement with experimental measurements over a wide range of strain rates, temperatures, and loading conditions
COBISS.SI-ID: 5006433
This paper presents an analysis of the main types of damage on industrial upper and lower hot-forging dies for hot forging of car steering mechanisms. They failed after a different number of forging strokes. Measurements of microhardness depth profiles and examinations of nitrided layers with an optical microscope were conducted. The design of die shape in sequential forging steps has the predominant role for a prolonged die life in comparison to the quality of nitrided die cavity surface. Improvements of die cavity design as well as improvements of nitriding process are suggested.
COBISS.SI-ID: 1088351