. "Rube\u0161ov\u00E1, Kate\u0159ina" . "Ma\u0161ek, Bohuslav" . "978-3-03835-073-6" . . "THERMEC 2013" . . "Las Vegas, United States" . "RIV/49777513:23210/14:43921955!RIV15-GA0-23210___" . . . "10.4028/www.scientific.net/MSF.783-786.801" . "23210" . . "RIV/49777513:23210/14:43921955" . "6"^^ . "Ai\u0161man, David" . "Jirkov\u00E1, Hana" . . . . . . "[FC5EC12BA7B5]" . "0255-5476" . . "By processing of steels in semi-solid state it is possible to achieve untypical structures also with commonly used steels. It can be demonstrated on the tool steel X210Cr12. After the semi-solid state processing, 96% of the structure can be created by metastable austenite. In the structure there are polyedric grains stored in a ledeburitic network. A combination of semi-solid state processing and rapid solidification represents a new method to achieve more significant modifications of a structure. Due to an intensive suppression of diffusive transformations and creating of supersaturated metastable structures, it is possible to achieve a very fine carbidic network or very fine precipitates. During the experiment two tool steels CPM 15V and CPM S30V were processed by an unconventional method. Since the steels are made by powder metallurgy, their initial structure is created by globular carbides stored in a ferritic matrix. Both materials have a high fracture of alloying elements, especially of C, V and Cr. The unconventional processing was made by mini-thixoforming which enables to use a small amount of processed metal. After heating to semi-solid state the material was quickly impressed in the cavity of metallic die where rapid solidification and rapid cooling occurred. Two variations of cooling were performed. In the first case the die was at room temperature, in the second one it was subcooled to -196\u00B0C by liquid nitrogen. Since the test sample was cooled from both sides and 1.5 mm thick, immensely high cooling rates were achieved. Influence of the cooling rate was noticeable also on structures containing high fracture of metastable austenite, martensite and carbides. An analysis of structures was performed with help of light, laser confocal and scanning electron microscopy. Chemical profiles of phases were determined by the EDX analysis and fraction of retained austenite in the structure was determined with help of the x-ray diffraction analysis."@en . "2013-12-02+01:00"^^ . . . . . "Semi-Solid Processing of Powder Steels in Cryogenically-Cooled Die"@en . . . "P(GAP107/12/2600), S" . . "undercoolde die; semi-solid; CPM; powder steel; mini-thixoforming"@en . "By processing of steels in semi-solid state it is possible to achieve untypical structures also with commonly used steels. It can be demonstrated on the tool steel X210Cr12. After the semi-solid state processing, 96% of the structure can be created by metastable austenite. In the structure there are polyedric grains stored in a ledeburitic network. A combination of semi-solid state processing and rapid solidification represents a new method to achieve more significant modifications of a structure. Due to an intensive suppression of diffusive transformations and creating of supersaturated metastable structures, it is possible to achieve a very fine carbidic network or very fine precipitates. During the experiment two tool steels CPM 15V and CPM S30V were processed by an unconventional method. Since the steels are made by powder metallurgy, their initial structure is created by globular carbides stored in a ferritic matrix. Both materials have a high fracture of alloying elements, especially of C, V and Cr. The unconventional processing was made by mini-thixoforming which enables to use a small amount of processed metal. After heating to semi-solid state the material was quickly impressed in the cavity of metallic die where rapid solidification and rapid cooling occurred. Two variations of cooling were performed. In the first case the die was at room temperature, in the second one it was subcooled to -196\u00B0C by liquid nitrogen. Since the test sample was cooled from both sides and 1.5 mm thick, immensely high cooling rates were achieved. Influence of the cooling rate was noticeable also on structures containing high fracture of metastable austenite, martensite and carbides. An analysis of structures was performed with help of light, laser confocal and scanning electron microscopy. Chemical profiles of phases were determined by the EDX analysis and fraction of retained austenite in the structure was determined with help of the x-ray diffraction analysis." . "Semi-Solid Processing of Powder Steels in Cryogenically-Cooled Die"@en . "44433" . . "Semi-Solid Processing of Powder Steels in Cryogenically-Cooled Die" . "4"^^ . . "4"^^ . "Semi-Solid Processing of Powder Steels in Cryogenically-Cooled Die" . "Materials Science Forum" . .