Uporovno varjenje visokotrdnega jekla DP 500

Samo Avguštin (Avtor), Damjan Klobčar (Mentor)

Povzetek

V avtomobilski industriji je prisotna težnja po manjši masi vozil. Ena od možnih rešitev za dosego tega cilja je, da naredimo vitko konstrukcijo vozila, kar pa zahteva uporabo materialov, ki imajo ugodno razmerje med trdnostjo in težo. Ob tem se pojavi izziv spajanja teh materialov. V proizvodnji srečujemo različne načine spajanja materiala, na primer: kovičenje, uporovno varjenje in druge postopke varjenja. Najpogosteje se uporablja točkovno uporovno varjenje, saj ga lahko avtomatiziramo in ob tem kontroliramo porabo energije na določen varjenec. V primerjavi s kovičenjem je uporovno varjenje hitrejše in cenejše. V diplomski nalogi so predstavljene osnove uporovnega točkovnega varjenja, prikazani so tudi posebni načini tega varjenja. Jeklo DP 500 smo varili pri različnih varilnih parametrih. S trgalnim strojem smo izvedli natezno strižni preizkus vzorcev. Iz dobljenih rezultatov in varilnih parametrov smo prikazali, kako posamezni varilni parametri vplivajo na: silo porušitve, strižno trdnost in razteznost (duktilnost). Vzorce smo vizualno pregledali in jih ocenili. Nepretrgane vzorce smo pripravili za mikroskopsko analizo in preverili, kakšna je usmerjenost zrn ter ali prihaja do razpok v zvaru. Po opravljeni mikroskopski analizi smo pomerili trdoto v zvaru in toplotno vplivani coni po Vickersovi metodi. Ugotovili smo, da pri varilnem toku 8 kA, času varjenja 200 ms in pri sili držanja 2,45 kN dobimo mejne dopustne varilne parametre, saj strižna trdnost zvara presega trdnost osnovnega materiala. Če želimo imeti dovolj veliko strižno trdnost, mora pri sili 3,68 kN in času 300 ms, varilni tok presegati 9,2 kA.

Ključne besede

uporovno varjenje;mikrolegirano jeklo;visokotrdno jeklo;natezna trdnost;trdota;

Podatki

Jezik:	Slovenski jezik
Leto izida:	2020
Tipologija:	2.11 - Diplomsko delo
Organizacija:	UL FS - Fakulteta za strojništvo
Založnik:	[S. Avguštin]
UDK:	621.791.762:669.14:539.412(043.2)
Št. ogledov:	442
Št. prenosov:	216
Ocena:	0 (0 glasov)
Metapodatki:

Ostali podatki

Sekundarni jezik:	Angleški jezik
Sekundarni naslov:	Resistance welding of DP 500 high-strength steel
Sekundarni povzetek:	The automotive industry is always trying to make the vehicles lighter. One of the solutions is to design them in a way, which requires the use of the materials that have good strength to weight ratio. With that comes the challenge of welding those materials. Therefore, we are commonly faced with riveting, resistance welding and other joining technologies regarding production. The most commonly used one is resistance spot welding, since it can be fully automatized, and we can monitor the energy consumption. Spot welding is much faster in comparison to riveting and therefore more cost efficient. The bachelors thesis presents the basics of resistance spot welding and shows a special method of this type of welding. DP 500 steel sheets were welded with different parameters, which were then put on the tensile and shear test. From the test results and the parameters we could show how different welding parameters affect the tensile strength, shear force and ductility. The test samples were also visually inspected. The samples which were not ruptured from testing were then prepared for microscopic analysis. Through the analysis we could determine the grain size and direction, but also observe whether there are any cracks in the material. In the last test, hardness was measured with Vickers hardness test in the weld and the heat affected zone. It was found that at a welding current of 8 kA, a welding time of 200 ms, and a holding force of 2.45 kN, the maximum allowable welding parameters are obtained, since the shear strength of the weld exceeds the strength of the base material. In order to have a sufficiently high shear strength, at a force of 3.68 kN and a time of 300 ms, the welding current must exceed 9.2 kA.
Sekundarne ključne besede:	resistance welding;microalloyed steel;high strength steel;tensile strength;hardness;
Vrsta dela (COBISS):	Diplomsko delo/naloga
Študijski program:	0
Strani:	XXII, 52 str.
ID:	11366544