Karakterizacija zavarenog spoja nehrđajućeg martenzitnog čelika

undergraduate thesis

• Author: Valentina Planinčić
• Mentor: Vera Rede (mentor)
• Granter: University of Zagreb; Faculty of Mechanical Engineering and Naval Architecture; Zagreb
• Defense date and country: 2024-02-28, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Mechanical Engineering

Abstract

U završnom radu provedena je karakterizacija zavarenog spoja martenzitnog nehrđajućeg
čelika X3CrNiMo13-4. U teorijskom dijelu rada opisane su osnovne vrste nehrđajućih čelika s
posebnim naglaskom na martenzitne nehrđajuće čelike, zavarljivost, toplinska obrada te
mikrostrukturne promjene ovih čelika. U eksperimentalnom dijelu analizirana je
makrostruktura i mikrostruktura te ispitana različita mehanička svojstva zavarenog spoja na
ploči debljine 50 mm, isporučene u normaliziranom stanju.
Provedena analiza strukture pokazala je da zavar ima pravilnu geometriju i jasno istaknute
prolaze. Osnovni materijal ima sitnozrnatu usmjerenu mikrostrukturu, sastavljenu od ferita i
vrlo sitnih karbida. U zoni utjecaja topline mikrostruktura je martenzitna, a metal zavara ima
tipičnu ljevačku strukturu. Mikrostrukturne promjene u zavarenom spoju utjecale su na
povećanje tvrdoće u odnosu na osnovni materijal, a najviše vrijednosti tvrdoće izmjerene su u
metalu zavara. U zoni utjecaja topline izmjerene su više vrijednosti žilavosti nego u metalu
zavara. U području zavarenog spoja izmjerena je viša vlačna čvrstoća od zajamčene vrijednosti
vlačne čvrstoće za osnovni materijal. Pri savojnom ispitivanju na kritičnoj površini lica i
korijena zavara nisu uočene pukotine. Dobiveni rezultati potvrđuju zadovoljavajuću kvalitetu
zavarenog spoja.

Abstract (english)

The final thesis included the characterization of the welded joint of martensitic stainless steel
X3CrNiMo13-4. The theoretical part of the thesis describes the basic types of stainless steels,
with a particular focus on martensitic stainless steels, weldability, heat treatment, and
microstructural changes in these steels. In the experimental part, the macrostructure and
microstructure were analyzed, and various mechanical properties of the welded joint on a 50
mm thick plate delivered in a normalized state were examined.
The structural analysis showed that the weld has a regular geometry and clearly defined passes.
The base material has a fine-grained directional microstructure composed of ferrite and very
fine carbides. In the heat-affected zone, the microstructure is martensitic, and the weld metal
has a typical casting structure. Microstructural changes in the welded joint led to an increase in
hardness compared to the base material, with the highest hardness values measured in the weld
metal. In the heat-affected zone, higher toughness values were measured than in the weld metal.
In the welded joint area, a higher tensile strength was measured compared to the guaranteed
tensile strength value for the base material. No cracks were observed during bending tests on
the critical surface of the weld face and root. The obtained results confirm the satisfactory
quality of the welded joint.

• Keywords: karakterizacija; martenzitni nehrđajući čelik; zavareni spoj
• Keywords (english): characterization; martensitic stainless steel; welded joint
• Language: croatian
• URN:NBN: urn:nbn:hr:235:927711
• Study programme: Title: Mechanical Engineering; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva (sveučilišni/a prvostupnik/ prvostupnica (baccalaureus/baccalaurea) inženjer/inženjerka strojarstva)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-02-27 12:05:37