PILEČEK Vít Západočeská univerzita v Plzni

Spoluautoři JIRKOVÁ Hana, KUČEROVÁ Ludmila, MAŠEK Bohuslav

Soft annealing is a conventional way of heat treatment for improving of formability of the parts produced by cold forming. Ductility and machinability of the material are increased through spheroidisation structure which is a result of this way of treatment. Long term hold at the annealing temperature, which represents significant energy and therefore economic requirements, is necessary for the formation of spheroidisation structure. Nowadays one of the main aims of new processing methods is to reduce the costs of production process in the field of heat treatment. One of possibilities is development of the ASR process (Accelerated Spheroidisation and Refinement). This is a progressive way of thermo-mechanical treatment with incremental deformation at the temperature around Ac1. Application of ASR leads to the spheroidisation structure with distributed carbides at significantly shorter times. Experiment dealt with optimization of ASR process on 54SiCr steel with ferrite-pearlite initial microstructure and lamellar pearlite morphology. Influence of strain in the range from φ=0,54 to φ=1,7 and cold deformation to break lamellar pearlite structure at the temperature of 700 °C was determined. Then the effect of length of the hold after deformation at the temperature 680 and 700 °C was described. It was found out that increasing holding time from 100 - 1000s at the deformation temperature has a positive influence on the recrystallization and distribution of spheroidised carbides. The recrystallized structures with ferrite and uniformly distributed spheroidised carbides were obtained. Hardness of this structure was only about 260 HV10 in comparison with initial lamellar structure with 283 HV10.