Vpliv staranja na razvoj mikrostrukture in mehanskih lastnosti jekla X20CrMoV

Velikajne, Nejc (author)

Jekla so v dan danes postala nepogrešljiv material in jih zaradi njihovih vsestranskih fizikalnih in mehanskih lastnostih srečamo praktično povsod. Poznanih je več tisoč različnih vrst jekel, velik del le teh pa se uporablja tudi v energetskih objektih. V termo elektrarnah večina komponent obratuje v zahtevnih pogojih, pri visokih temperaturah in visokih tlakih. Posledično se zahteva materiale z visokimi mehanskimi lastnostmi pri povišanih temperaturah, visoko odpornost proti koroziji, odpornost proti deformaciji zaradi lezenja ter so odporna na ciklično temperaturno utrujanje. Jeklo X20CrMoV12-1 je eno od materialov, ki so primerni za tovrstno uporabo. Med dolgotrajnim obratovanjem naprav pri temperaturi do 550°C prihaja do sprememb v mikrostrukturi. Poznavanje in zasledovanje le teh pa je ključno za oceno dobe trajanja komponente. V okviru diplomske naloge smo analizirali cev pregrevalnika pare iz Termoelektrarne Šoštanj. Za njo je 235.900 delovnih ur pri temperaturi pare 500°C in tlaku 180 bar. Izvedli smo primerjavo med staro ter novo cevjo. Površinsko analizo, analizo depozitov, mikrostrukturne značilnosti, natezni preizkus trdnosti in meritve trdote smo izvedli na obeh ceveh ter podali vpliv staranja na razvoj mikrostrukture in na mehanske lastnosti omenjenega jekla.

• Language: Slovenian
• Keywords: X20CrMoV12-1, temperaturno obstojna jekla, karbidni izločki, mikrostruktura, natezna trdnost, trdota.
• Work type: Bachelor thesis/paper
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Year: 2018
• PID: 20.500.12556/RUL-103893
• COBISS.SI-ID: 1765983
• Publication date in RUL: 28.09.2018

VELIKAJNE, Nejc, 2018, Vpliv staranja na razvoj mikrostrukture in mehanskih lastnosti jekla X20CrMoV [online]. Bachelor’s thesis. [Accessed 24 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=103893

Secondary language

• Language: English
• Title: Influence of aging on microstructure development and mechanical properties of X20CrMoV steel

Abstract

Steel is nowadays an indispensable material and because of its versatile physical and mechanical properties it is practically ubiquitous. There are a few thousand different varieties of steels, a great part of which is used also in power plants. In thermal power stations most components operate in difficult conditions, at high temperatures and high pressures. Consequently there is a need for materials with better mechanical properties at high temperatures, high corrosion resistance, creep-induced strain resistance and thermal cyclic fatigue. X20CrMoV12-1 steel is one of the materials suitable for such purposes. Microstructure can be changed when components operate at temperatures up to 550 °C for long periods. Understanding and monitoring of such changes is crucial for estimating fitness of such components. In this graduation thesis a tube from steam superheater from Šoštanj thermal power plant is analysed. It clocked 235.900 hours of service at steam temperature of 500 °C and 180 bar of pressure. A comparison was made between this and a new tube. Surface analysis, deposit analysis, microstructure characterisation, tensile test and hardness test were conducted with both tubes and the effect of ageing on microstructure and mechanical properties of said steel was characterised.

• Keywords: X20CrMoV12-1, heat resistant steel, carbide efflorescence, microstructure, tensile strenght, hardness.