Vpliv postopka toplotne obdelave na mikrostrukturo in mehanske lastnosti martenzitnega nerjavnega jekla X20Cr13

Božank, Jure (author), Naglič, Iztok (mentor), Janet, Bernarda (co-mentor)

V diplomskem delu smo obravnavali vpliv toplotne obdelave na mikrostrukturo in mehanske lastnosti kromovega martenzitnega nerjavnega jekla X20Cr13. Uporabili smo tri temperature avstenitizacije in tri režime ohlajanja, ki smo jih dosegli z ohlajanjem v vodi, olju in na zraku. Po kaljenju so bili vzorci popuščani pri konstantni temperaturi in dveh različnih časih popuščanja. Karakterizacija mikrostrukture toplotno obdelanega jekla je potekala z uporabo svetlobne mikroskopije. Določili smo velikost prvotnih avstenitnih zrn po ASTM E112. S pomočjo dilatometrije smo določili temperature premen Ac1, Ac3, Mf in Ms. Mehanske lastnosti smo ugotavljali s pomočjo nateznega preizkusa, preizkusa udarne žilavosti in z merjenjem trdote. Za karakterizacijo morfologije loma smo uporabili vrstično elektronsko mikroskopijo. Določili smo tudi prehodno temperaturo žilavosti za jekla pri različnih režimih toplotne obdelave. Na podlagi vseh rezultatov smo določili optimalno toplotno obdelavo tega jekla, ki vključuje temperaturo avstenitizacije 1000 °C, čemur sledi kaljenje na zraku in 5 urno popuščanje pri temperaturi 670 °C.

• Language: Slovenian
• Keywords: jeklo X20Cr13, toplotna obdelava, mikrostruktura, mehanske lastnosti, prehodna temperatura žilavosti, morfologija loma
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2020
• PID: 20.500.12556/RUL-120904
• COBISS.SI-ID: 32968963
• Publication date in RUL: 26.09.2020

Secondary language

• Language: English
• Title: Influence of heat treatment process on microstructure and mechanical properties of martensitic stainless steel X20Cr13

Abstract

This work deals with the influence of heat treatment on the microstructure and mechanical properties of chromium martensitic stainless steel X20Cr13. Three different austenitization temperatures and three different cooling rates accomplished by quenching in water, oil and air were used. Each sample of steel has been additionally tempered at constant temperate for two different times. Microstructure of heat treated steel was characterized by using light microscopy and prior austenite grans size was determined according to ASTM E112. Dilatometry was used to determine the Ac1, Ac3, Mf, Ms temperatures. Mechanical properties were determined by using tensile testing, impact toughness testing and hardness testing. Scanning electron microscopy was used for the characterization of fracture morphology. Fracture appearance transition temperature (FATT) was also determined for this steel heat treated by different procedures. On the basis of these properties the optimal heat treatment procedure for this steel was selected. Such a heat treatment involves austenitization temperature of 1000 °C followed by quenching in air and tempering at XXX °C for 5 hours.

• Keywords: steel X20Cr13, heat treatment, microstructure, mechanical properties, fracture appearance transition temperature, fracture morphology