diplomsko delo
Diego Uršič (Author), Bojan Podgornik (Mentor)

Abstract

Podhlajevanje orodnega jekla je široko sprejeta metoda v metalurški stroki, in sicer gre za dodatno toplotno obdelavo, ki se uporablja za povečanje transformacije avstenita v martenzit ter izboljšanje lastnosti ulitkov in strojno obdelanih delov. V praksi je najpogosteje uporabljana temperatura –80 °C, ki je značilna za plitvo podhlajevanje. Na drugi strani pa poznamo globoko podhlajevanje, pri katerem jeklo podhladimo na temperaturo –196 °C. Orodna jekla so legirana s tvorbo karbidnih elementov (tipično: vanadij, molibden in krom), poleg tega nekatere vrste jekla vsebujejo tudi kobalt, ki jima dviguje temperaturo, pri kateri se prične transformacija martenzita, in temperaturo, pri kateri se postopek konča. Dodajanje legirnih elementov služi predvsem dvema namenoma: izboljšanju trdote in zagotovitvi termično bolj stabilnih karbidov od cementita. Ob predpostavki, da je orodno jeklo ustrezno toplotno obdelano, so njegove lastnosti močno odvisne od legirnih elementov, ki so bili dodani, in njihove koncentracije. Namen diplomskega dela je določiti potencial procesa globokega podhlajevanja za izboljšanje lastnosti orodnih jekel ter izdelati analizo vpliva podhlajevanja na mehanske, nosilne in protiobrabne lastnosti orodnih jekel. V okviru eksperimentalnega dela sta bili izvedeni klasična vakuumska toplotna obdelava ter toplotna obdelava z vključenim globokim podhlajevanjem na treh tipih orodnega jekla za delo v hladnem. Njima sta sledila merjenje trdote, lomne žilavosti in obrabne odpornosti. Praktična vrednost diplomskega dela je v določitvi vpliva podhlajevanja in medsebojne odvisnosti mehanskih in triboloških lastnosti orodnih jekel za delo v hladnem.

Keywords

podhlajevanje;toplotna obdelava;orodno jeklo;trdota;lomna žilavost;obraba;diplomske naloge;

Data

Language: Slovenian
Year of publishing:
Typology: 2.11 - Undergraduate Thesis
Organization: UNG PTF - Faculty of Engineering and Management
Publisher: [D. Uršič]
UDC: 621.7+621.9
COBISS: 4503547 Link will open in a new window
Views: 6005
Downloads: 265
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Other data

Secondary language: English
Secondary title: Potential of deep cryogenic treatment for improving properties of tool steels
Secondary abstract: Cryogenic treatment of steel is widely accepted within the metallurgical profession as a supplemental treatment that can be used to enchance the transformation of austenite to martensite and to improve stress relief of castings and machined parts. Common practice identifies -80 °C as the optimum temperature for cryogenic treatment. On the other side, there is deep cryogenic treatment of steel in witch material is brought to a temperature of -196 °C. Tool steels are alloyed with carbide forming elements (typically: vanadium, molybdenum and chromium), furthermore some tool steels also contain cobalt, which respectively raises the temperature at which martensite transformation initiates and at which the transformation is completed. Addition of alloying elements serves primarily two purpose first to improve the hardenabillity and secound to provide harder and thermally more stable carbides than cementite. Assuming proper heat treatment, the properties of a tool steel strongly depend on type of alloying elements and their respective concentrations. The purpose of the study is to determine the potential of the deep cryogenic treatment process for improving the properties of tool steels and produce an analysis of the impact of undercooling mechanical, carrier and anti-wear properties of tool steels. Part of the samples was conventional vacuum heat treated and the other part was heat treated with inclusive of deep cryogenic treatment of the three types of tool steel for cold work. This was followed by measuring the hardness, fracture toughness and wear resistance. The practical value of the thesis is the determination of the effect of deep cryogenic treatment and interdependence of mechanical and tribological properties of cold work tool steels.
Secondary keywords: Cryogenic treatment;heat treatment;tool steel;hardnes;fracture toughnes;wear resistance;
URN: URN:SI:UNG
Type (COBISS): Bachelor thesis/paper
Thesis comment: Univ. v Novi Gorici, Poslovno-tehniška fak.
Pages: XII, 67, str.
ID: 9166324