Napetosna korozija zavarenih spojeva visokolegiranih Cr-Ni čelika

master's thesis

• Title (english): Stress corrosion cracking of high alloyed Cr-Ni steels welded joints
• Author: Josip Kranželić
• Mentor: Vinko Šimunović (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2017-07-20, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

Cilj ovog diplomskog rada je istražiti uzroke, mehanizme, posljedice i načine zaštite od napetosne korozije. Napetosna korozija je vrlo podmukli oblik korozije, čije posljedice nerijetko zaustavljaju čitave pogone, jer se teško uočava zbog svoje potpovršinske naravi, tj. izostanka tragova korozije na površini materijala. Iako na površini nema znakova korozije, istodobno mehanička svojstva materijala značajno opadaju, sve dok ne dođe do krhkog loma.

U teorijskom dijelu rada su detaljno opisani mehanizmi nastajanja napetosne korozije na nehrđajućim čelicima te različiti oblici napetosne korozije i podložni materijali za ovaj oblik korozije. Također su opisani različiti načini ispitivanja i sprječavanja napetosne korozije.

U eksperimentalnom dijelu rada je ispitivan utjecaj zavarivanja, vrste nehrđajućeg čelika, različitih agresivnih medija i vrste naprezanja na nastanak i intenzitet napetosne korozije. Rezultati provedenih ispitivanja ukazuju na značajan utjecaj svih navedenih čimbenika na pojavu napetosne korozije ispitivanih nehrđajućih čelika.

Abstract (english)

The aim of this graduate thesis is to explore the causes, mechanisms, consequences and ways of protection from stress corrosion cracking (SCC). SCC is a very serious form of corrosion and is often the cause of stoppings of entire production process. It is difficult to discover because of its subsurface nature, i.e. lack of corrosion marks on the surfaces of the material. Although there are no signs of corrosion on the surface, at the same time, the mechanical properties of the material significantly decrease until a brittle fracture occurs.

The theoretical part describes the mechanisms of the formation of SSC, various forms of it and the susceptible materials for this type of corrosion. Different ways of testing and preventing SSC are also described.

In the experimental part the effect of heat input during welding, the type of stainless steel, various aggressive media and type of stress on the formation and mechanisms SSC was investigated. The results of conducted testings show great influence of all mentioned factors on SCC of tested stainless steels.

• Keywords: napetosna korozija; nehrđajući čelici; zavarivanje; kloridi
• Keywords (english): stress corrosion cracking; stainless steel; welding; chlorides
• Language: croatian
• URN:NBN: urn:nbn:hr:235:971262
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra inženjer/inženjerka strojarstva (magistar/magistra inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-05-22 19:37:00