Vpliv notranjih napetosti na spremembo oblike C-obročev iz jekla 42CrMo4

diplomsko delo

Tilen Šušteršič (Author), Milan Bizjak (Mentor)

Abstract

Namen diplomskega dela je bila raziskava vpliva nitridiranja na spremembo dimenzij elementov iz 42CrMo4 jekla oblike polnih obročev in C-obročev. Nitridiranje temelji na obogatenju površinskega sloja z dušikom, ki sam ali pa v spojini povzroča površinsko utrditev. Obogatitev površinskega sloja povzroči povečanje volumna in posledično spremembo dimenzij elementa in nastanek notranje napetosti. Na spremembo geometrije elementa lahko vplivajo tudi v materialu prisotne notranje napetosti. Eksperimentalno delo je obsegalo merjenje zaostalih notranjih napetosti v jeklu v dobavnem stanju, po žarjenju za odpravo zaostalih napetosti in nitridiranju. Merjenje oblik in dimenzij smo izvedli s 3D koordinatnim merilnikom. Za karakterizacijo mikrostrukture smo uporabili svetlobno in vrstično elektronsko mikroskopijo. Rezultati preiskave kažejo, da je na spremembo dimenzij preizkušancev najbolj vplival dušik, ki privede pod vplivom difuzije do nastanka površinskega sloja nitridov. Po nitridiranju na površini ostanejo tlačne napetosti, ki povečajo obrabno obstojnost in dinamično trdnost površine. Pri toplotnih obdelavah nastale termične napetosti zaradi neenakomernega ohlajanja po globini nimajo opaznega vpliva na spremembo dimenzij elementov.

Keywords

obroč;sprememba dimenzije;nitridiranje;metalografska analiza;zaostale napetosti;

Data

Language:	Slovenian
Year of publishing:	2022
Typology:	2.11 - Undergraduate Thesis
Organization:	UL NTF - Faculty of Natural Sciences and Engineering
Publisher:	[T. Šušteršič]
UDC:	669
COBISS:	133647619
Views:	64
Downloads:	9
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary title:	influence of residual stresses on the deformation of C-rings of 42CrMo4 steel
Secondary abstract:	The objective of this study was to investigate the effect of nitriding on the change in element dimensions of full circles and C-circles of 42CrMo4 steel. Nitriding is based on the enrichment of the surface layer with nitrogen, which alone or in compounds causes surface hardening. The enrichment of the surface layer leads to an increase in volume and thus to a change in element dimensions and the development of residual stresses. The change in element geometry can also be affected by the presence of residual stresses in the material. Experimental work includes measurement of residual stresses in the initial state of the steel, after annealing to relieve residual stresses, and after nitriding. A 3D coordinate measuring machine was used to measure shapes and dimensions, and an optical microscope and a scanning electron microscope were used to characterize the microstructure. The results of the study show that the change in the dimensions of the subjects was most affected by nitrogen, which leads to the formation of a surface layer of nitrides through diffusion effects. After nitriding, only compressive stresses remain on the surface, which increases the durability and dynamic hardness of the surface. During heat treatment, the new thermal stresses have no noticeable effect on the change of element dimensions due to the non-uniform cooling in depth.
Secondary keywords:	ring;dimension change;nitriding;metallographic analysis;residual stresses;
Type (COBISS):	Bachelor thesis/paper
Study programme:	0
Embargo end date (OpenAIRE):	1970-01-01
Thesis comment:	Univ. v Ljubljani, Naravoslovnotehniška fak., Oddelek za materiale in metalurgijo
Pages:	XII, 55 f.
ID:	17052840