Poboljšavanje svojstava brzoreznog čelika 1.3302u vrućem stanju

Laboratory investigation of hot workability of 1.3302 high speed steel was carried out and its improving was achieved. Hot compression tests for the determination of optimal soaking temperature as well as for the study of hot workability in temperature range 1150-850 ºC, strain rates range 0,001-6 s–1 and applied strain up to 0,9 were performed. Microstructure of deformed specimen was analyzed. Apparent activation energies for hot working for upper and for lower temperature range were calculated. Onsets of dynamical recrystallization for applied deformation conditions on the basis of calculated strain hardening ratewere determined. Extending of hot working temperature range at its lower limit, i.e. down to 850 ºC, by applying optimal soaking temperature was obtained.Data su laboratorijska istraživanja prerađivačkih svojstva brzoreznog čelika 1.3302 u vrućem stanju koji su doprinijeli poboljšanju tih svojstava. Izvedeni su pokusi vrućeg sabijanja za određivanje temperature zagrijavanja kao i prerađivačkih svojstva u temperaturnom rasponu 1 150-850 ºC, brzinom deformacije 0,001-6 s–1 i stupnja deformacije do 0,9. Analizirana je mikrostruktura deformiranih proba.Izračunane su prividne aktivacijske energije za vruću preradu za gornje i donje temperaturno područje. Počeci dinamičke rekristalizacije za primijenjene uvjete deformacije utvrđeni su na temelju izračuna brzine deformacijskog očvršćavanja. Primjenjujući optimalno temperaturu zagrijavanja dobiveno je povećanje vrućeg radnog temperaturnog raspona na svojoj donjoj granici, odnosno do 850 ºC

Predicting of Roll Surface Re-Machining Using Artificial Neural Network

The paper presents a model for predicting the roll wear in the hot rolling process. It includes all indicators from the entire continuous rolling line that best predict the roll wear in the hot rolling process. Data for model development were obtained from annual production on the first rolling stand of the continuous roll mill. The main goal of the research was to determine significant parameters that affect the wear of the roll in the process of hot rolling. It has been found that the amount of rolled material before the re-machining of the roll surface has the greatest impact on the life of the roll contour. Therefore, the amount of material rolled before re-machining of the roll was used to estimate the wear of the roll. An artificial neural network was used to predict this amount of rolled material and was validated using data from one-year production

Influence of nutritional risk and perioperative nutritional support on outcome of surgical treatment in patients with colorectal cancer

Meeting minutes from the Faculty Senate of the University of Northern Iowa

Increasing of hot workability of 1.3302HIGH speed steel

Laboratory investigation of hot workability of 1.3302 high speed steel was carried out and its improving was achieved. Hot compression tests for the determination of optimal soaking temperature as well as for the study of hot workability in temperature range 1150-850 ºC, strain rates range 0,001-6 s<sup>–1/sup> and applied strain up to 0,9 were performed. Microstructure of deformed specimen was analyzed. Apparent activation energies for hot working for upper and for lower temperature range were calculated. Onsets of dynamical recrystallization for applied deformation conditions on the basis of calculated strain hardening ratewere determined. Extending of hot working temperature range at its lower limit, i.e. down to 850 ºC, by applying optimal soaking temperature was obtained

Primjena novo razvijenih testova sa grijanjem i unutarnjim hlađenjem uzoraka od alatnog čelika za različite primjene

In this study two new tests were developed, i.e., with continuous internal water cooling as well as discontinuous internal water and air cooling. It was proved that the first type of testing is appropriate for simulating the time course of the temperature at a selected depth of a thermally loaded, hot-working die surface layer, i.e., the temperature field on the die surface layer. The second type of testing is appropriate for a study of the thermal fatigue resistance of a tool material.U ovom istraživanju razvijeni su dva nova testa, tj. test sa kontinuiranom unutarnjim vodenim hlađenjem, kao i test sa diskontinuiranom unutarnjim vodenim i zračnim hlađenjem. Dokazano je da je prvi tip ispitivanja primjeran za simulaciju vremenske raspodjele temperature na odabranoj dubini termalno opterećene površine alata za vruću preradu. Druga vrsta ispitivanja je prikladno za proučavanje otpora termalnog zamora alatnog materijala