UIC-preporuke za uporabu čelika za željezničke tračnice

The paper elaborates overlook criteria to determine the choice and recommendations for the use of rail steel grades according to draft UIC-recommendations leaflet 721R from 2003. which was prepared by Infrastructure Commission from International Union of Railways based on European standard EN 13674-1.U članku su pregledno obrađeni kriteriji za izbor i preporuke za uporabu čelika za željezničke tračnice prema nacrtu UIC-preporuka 721R iz 2003. koji je izradila Komisija za Infrastrukturu Međunarodne željezničke unije (UIC) na temelju Europske norme EN 13674-1

Trendovi s europskih konferencija o kvaliteti

European annual conferences on quality (EOQ) have been held continuously since 1957. Total number of 45 conferences has been registered till 2001. This paper gives a concise review on topics and mottos of the 10 last conferences, their way of reasoning, final messages and trends in quality management.Europske godišnje konferencije o kvaliteti (EOQ) održavaju se od 1957. godine i do 2001. g. održano je ukupno 45 konferencija. Ovaj rad sadrži koncizne preglede o sadržajima 10 posljednjih konferencija, načinu razmišljanja, zaključnim porukama i trendovima upravljanja kvalitetom

Damage to Railway Rails Caused by Exploitation

In modern railway exploitation rails are submitted to a constant increase of speed and loading on the vehicle axles and to constant stress increase in welded railway tracks. Therefore, modern railway rails production technology and exploitation in European Community have require a new philosophy and content for the proposals of new European standards for the manufacturing and delivery of railway rails (series pr EN 13674 and other recommendations). In this paper an overlook over the new requirements mainly given in EN 13674-1/2004, the criteria for the selection of steel grade and the valuation of damages to railway rails caused by exploitation especially on the head of rails are given

Kinetika rekristalizacije tijekom vrućeg oblikovanja čelika

The theory of kinetics of static recrystallization of steel during hot forming links the phenomenon to certain critical strain, grain size, strain rate, activation energy and temperature. The basic description is provided by the Avrami equation. An overview of equations used was compiled and comments on selected parameters prepared.Teorija kinetike statičke rekristalizacije čelika tijekom vrućeg oblikovanja ovu pojavu povezuje s kritičnom deformacijom, veličinom zrna, brzinom deformacije, aktivacijskom energijom te s temperaturom. Osnovni opis pruža Avrami jednadžba. Rad pruža pregled korištenih jednadžbi i raspravu pojedinih parametara

Tribološka svojstva kočnih papuča s povišenim udjelom fosfora

The research has been conducted applying dry friction method using logs made out of brake shoes, sliding them on rotating disc out of the same material as the train wheels. Chemical composition, structure and hardness of the brake shoes and their influence on brake shoe wear were tested under simulated laboratory conditions: wheel - brake shoe. It has been found out that brake shoe wear resistance depends mainly upon phosphorus content and the structure, much more than on hardness values.Ispitivanje je provedeno u uvjetima suhog trenja sklizanja kladica izrađenih iz kočnih papuča po rotirajućem disku od istog materijala iz kojega se izrađuju i kotači vlakova. Analiziran je utjecaj kemijskog sastava, strukture i tvrdoće papuča na trošenje u simuliranim uvjetima ispitivanja kotač - papuča na tribološkom uređaju u laboratoriju. Utvrđeno je da otpornost trošenju papuča mnogo više ovisi o udjelu fosfora i strukturi nego o tvrdoći

Elektrokemijska mjerenja na pilot uređaju za istraživanje korozije toplo pocinčanih cijevi

A problem of the electrochemical measurement results accuracy has appeared during a performed complex long term pilot plant investigations of the hot-dip galvanized steel pipes corrosion in warm potable water. After a short introduction, the first part of the paper describes the pilot plant with pipe specimen assembly series. Specimens have been made of zinc, steel and hot-dip galvanised steel. The second part of the paper presents the performed electrochemical measurements without computer aids and displays an example of the obtained final results. The third part of the paper is devoted to the development of the system for the computer aided monitoring of the mixed electrode potentials and electric currents between short circuited specimens.Tijekom provedenog složenog dugotrajnog eksperimentalnog istraživanja korozije toplo pocinčanih čeličnih cijevi u toplim pitkim vodama pojavio se problem pouzdanosti rezultata elektrokemijskih mjerenja. Nakon kratkog uvoda, u prvom dijelu rada je opisan pilot uređaj s nizovima sklopova uzoraka. Uzorci cijevi su bili izrađeni od cinka, čelika i toplo pocinčanog čelika. U drugom dijelu rada su opisana provedena elektrokemijska mjerenja sa sustavom mehaničkih sklopki i prikazan jedan primjer dobivenih rezultata. Treći dio rada je posvećen razvoju sustava za računalom podržano praćenje mješovitih elektrodnih potencijala i električnih struja između kratko spojenih uzoraka

Utjecaj boridnih faza na duktilnost materijala

Results of the boride surface layers investigation, obtained by the torsion and bending methods, point to the better ductility of the mono-phase Fe2B boride layers then the binary-phase FeB + Fe2B boride layers. This is especially outstanding in the case of peaces that are under higher thermal and mechanical load, where the binary-phase layer because of higher local stresses has higher tendency to fall of, respectively to shell.Istraživanje duktilnosti boridnih slojeva pomoću metode torzije i savijanja ukazuje da jednofazni boridni slojevi Fe2B u odnosu na dvofazne boridne slojeve FeB + Fe2B imaju bolju duktilnost. To naročito dolazi do izražaja kod proizvoda koji su toplinski i mehanički više napregnuti, gdje su veći specifični pritisci, tada je dvofazni boridni sloj sklon bržem otpadanju, odnosno ljuštenju

Damage to Railway Rails Caused by Exploitation

In modern railway exploitation rails are submitted to a constant increase of speed and loading on the vehicle axles and to constant stress increase in welded railway tracks. Therefore, modern railway rails production technology and exploitation in European Community have require a new philosophy and content for the proposals of new European standards for the manufacturing and delivery of railway rails (series pr EN 13674 and other recommendations). In this paper an overlook over the new requirements mainly given in EN 13674-1/2004, the criteria for the selection of steel grade and the valuation of damages to railway rails caused by exploitation especially on the head of rails are given

Damage to Railway Rails Caused by Exploitation

In modern railway exploitation rails are submitted to a constant increase of speed and loading on the vehicle axles and to constant stress increase in welded railway tracks. Therefore, modern railway rails production technology and exploitation in European Community have require a new philosophy and content for the proposals of new European standards for the manufacturing and delivery of railway rails (series pr EN 13674 and other recommendations). In this paper an overlook over the new requirements mainly given in EN 13674-1/2004, the criteria for the selection of steel grade and the valuation of damages to railway rails caused by exploitation especially on the head of rails are given