Vpliv dvojnega izločevalnega utrjevanja na lastnosti debele pločevine iz jekla 17-4 PH : magistrsko delo

Šabec Vinkovič, Jakob (author), Kosec, Borut (mentor), Robič, Robert (comentor)

Primarna toplotna obdelava debele pločevine iz jekla, opredeljenega v standardu UNS S17400, oziroma po standardu ASTM A693 17-4-4/17-4 PH, je izločevalno utrjevanje, ki se sestoji iz raztopnega žarjenja pri temperaturi 1050 °C in gašenja, kateremu glede na zahtevane končne mehanske karakteristike sledi staranje na primerni temperaturi. Zaradi vedno večjega povpraševanja končnih kupcev debele pločevine iz jekla 17-4PH po dvojnem izločevalnem utrjevanju, ter že predhodno izvedenih preiskav smo na predhodno industrijsko raztopno žarjenih vzorcih izvedeli dvostopenjsko staranje ter preiskave mehanskih lastnosti in pregled mikrostrukture. Izločevalno utrjevanje jekla 17-4 PH opredeljujeta standarda ASME SA 693 in ASTM A693. Bolj podrobno smo preučili stanje H1150M. Na predhodno industrijsko raztopno žarjenih in gašenih vzorcih smo izvedli dvostopenjsko staranje, ki ga opisuje stanje H1150M in je bilo izvedeno v prvi fazi pod laboratorijskimi pogoji. Najprej so bili vzorci starani pri temperaturi 760 °C 2 uri, skladno s stanjem H1400. Temu je po ustreznem ohlajanju sledilo ponovno staranje na temperaturi 621 °C 4 ure skladno s stanjem H1150. V drugi fazi je sledilo industrijsko dvostopenjsko staranje v petconski komorni peči pod enakimi pogoji kot pri laboratorijskem staranju ter testiranje predpisanih mehanskih lastnosti. Osnovni namen magistrskega dela je bil zagotoviti doseganje predpisanih mehanskih lastnosti v dvojno staranem stanju skladno s standardom ASTM A693 in postavitev tehnologije toplotne obdelave ter razširiti možnost končnih dobavnih stanj kupcem, skladno s povpraševanjem.

• Language: Slovenian
• Keywords: jeklo 17-4 PH, izločevalno utrjevanje, dvostopenjsko staranje, standard ASTM A693, mikrostruktura.
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: NTF - Faculty of Natural Sciences and Engineering
• Place of publishing: Ljubljana
• Publisher: J. Šabec Vinkovič
• Year: 2024
• Number of pages: XV, 47 f.
• PID: 20.500.12556/RUL-166122
• UDC: 669
• COBISS.SI-ID: 220034051
• Publication date in RUL: 20.12.2024

ŠABEC VINKOVIČ, Jakob, 2024, Vpliv dvojnega izločevalnega utrjevanja na lastnosti debele pločevine iz jekla 17-4 PH : magistrsko delo [online]. Master’s thesis. Ljubljana : J. Šabec Vinkovič. [Accessed 26 March 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=166122

Secondary language

• Language: English
• Title: Influence of double precipitation hardening properties of heavy plates from steel 17-4 PH : master's thesis

Abstract

The primary heat treatment for thick steel plates is defined by the UNS S17400 standard, or according to the ASTM A693 17-4-4 / 17-4 PH standard is precipitation hardening, which involves solution annealing at temperature of 1050 °C followed by quenching. Depending on the required final mechanical properties, this is followed by aging at an appropriate temperature. Due to the increasing customer demand for thick 17-4 PH steel plates treated with double precipitation hardening and previously conducted investigations of double – stage aging and examinations of mechanical properties and microstructure was conducted on pre-industrially solution-annealed samples. Precipitation hardening of 17-4PH steel is defined by ASME SA 693 and ASTM A693 standards. In this study, we focused on the condition H1150M. Double-stage aging, as described by the condition H1150M, was conducted on previously industrially solution-annealed and quenched samples under laboratory conditions in the first phase. The samples were aged at 760 °C for 2 hours, according to condition H1400. After appropriate cooling, the samples were aged again at 621 °C for 4 hours, according to condition H1150. In the second phase, industrial two-stage aging was carried out using a five-zone chamber furnace under conditions identical to those in the laboratory trials. Subsequently, the prescribed mechanical properties were tested. The primary goal of this master’s thesis was to ensure the achievement of the prescribed mechanical characteristics in the double-aged condition in accordance with the ASTM A693 standard, to establish the heat treatment technology, and to expand the range of final delivery conditions for customers according to their demands.

• Keywords: 17-4 PH steel, Precipitation hardening, two-stage aging, ASTM A693 standard, microstructure.