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

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

Primjena SEM i EDS analiza u istraživanju poroznosti Al-Si-Cu lijevanog stapa

Porosity formation was detected in the casting thinnest section in the proximity of the as cast surface and near the wall centerline. In order to investigate the cause of the porosity formation light microscopy was used to define as cast structure. After initial findings SEM and EDS analyses were performed. Based on the results it is possible to define cause of the observed porosity. A number of pores originates from the mould filling stage and entrainment of the oxide films, while others appear due to insufficient feeding during solidification.Kod najtanjeg presjeka stijenke odljevka otkrivena je pojava poroznosti neposredno ispod površine stijenke, kao i u zoni sredine stijenke. Kako bi se utvrdio uzrok pojave poroznosti primijenjena je svjetlosna mikroskopija za određivanje lijevane strukture. Nakon prvobitnih opažanja provedene su SEM i EDS analize. Na temelju dobivenih rezultata moguće je odrediti uzroke nastanka otkrivene poroznosti. Određeni broj pora nastaje zbog zarobljavanja oksidnog filma tijekom faze popunjavanja kalupa, dok je ostatak poroznosti posljedica neadekvatnog napajanja tijekom skrućivanja

Use of SEM and EDS analysis in the investigation of Al-Si-Cu piston alloy cast porosity

Porosity formation was detected in the casting thinnest section in the proximity of the as cast surface and near the wall centerline. In order to investigate the cause of the porosity formation light microscopy was used to define as cast structure. After initial findings SEM and EDS analyses were performed. Based on the results it is possible to define cause of the observed porosity. A number of pores originates from the mould filling stage and entrainment of the oxide films, while others appear due to insufficient feeding during solidification