1. Suitability of heat treatment for crack resistance of material in the connection part of heavy transporter for liquid slagTomaž Vuherer, Ljubica Milović, Milorad Zrilić, Ivan Samardžić, Vladimir Gliha, 2013, kratki znanstveni prispevek Opis: The post weld heat treatment (PWHT) was used to reduce the level of the residual stresses and increase of the crack resistance of the materal in the cnnection part. The article presents the results of the residual stress measurements immediately after welding and after the stress relaxation by the PWHT.
Ključne besede: weld, heat treatment, residual stress, stress relaxation, crack resistance
Objavljeno: 03.07.2017; Ogledov: 1610; Prenosov: 61
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2. Microstructural investigation of the heat-affected zone of simulated welded joint of P91 steelTomaž Vuherer, Marko Dunđer, Ljubica Milović, Milorad Zrilić, Ivan Samardžić, 2013, izvirni znanstveni članek Opis: In the process of testing real components exposed to elevated temperature, it is not possible to neglect cracks. The most significant cracks can be induced by welding, which is applied for joining of structural components. Pressure equipment in service is also exposed to high pressure and high stresses. Materials for their manufacturing are designed to resist high stressat elevated temperature, and to meet requirements regarding creep resistance. The objective of this study is to investigate microstructure of different regions of the heat affected zone in T/P91 steels by using thermal simulation instead of welding.
Ključne besede: welded joints, microstructures, P91 steel, heat-affected zone, heat treatment
Objavljeno: 10.07.2015; Ogledov: 596; Prenosov: 128
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3. New design of closed loop servo hydraulic device for thermal fatigue testingMilorad Zrilić, Tomaž Vuherer, Ljubica Milović, Stojan Sedmak, 2009, izvirni znanstveni članek Opis: The paper presents the proposal of new design of closed loop servo hydraulic device for fatigue testing, induced by mechanical loading spectrum and variation of temperature. In addition to easier testing performance and more accurate results, the use of this solution offers significant saving in test duration and energy consummation.
Ključne besede: utrujanje, termično utrujanje, servohidravlični trgalni stroj s povratno zanko, preizkušanje s spektrom obremenitve
Objavljeno: 10.07.2015; Ogledov: 694; Prenosov: 28
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4. Determination of fatigue crack growth parameters in welded joint of HSLA steelLjubica Milović, Tomaž Vuherer, Zoran Radaković, Blagoj Petrovski, Miodrag D. Janković, Milorad Zrilić, Darko Daničić, 2011, objavljeni znanstveni prispevek na konferenci Opis: The structural integrity and operational safety of welded pressure vessels primarily depends on the behaviour of weldments. In spite of all efforts in material production and improvements in welding techniques, including strict codes, requirements and directives, the crack occurrence in welded structures cannot be completely excluded. This is why fracture mechanics analysis is inevitable in the structural integrity assessment of all welded structures. Examples of practical application of fracture mechanics parameters in cracked pressure vessel structural integrity are considered. This paper shows the determination of parameters of the fatigue crack for constituents of welded joints produced of high strength low alloyed steel Nionikral-70 (yield strength 700 MPa). Results have shown that the position of notch and crack initiation affect the values of the stress intensity range of fatigue threshold ?Kth and parameters in the Paris' equation.
Ključne besede: HSLA jekla, rast razpoke, HSLA steel, crack growth rate, fatigue threshold, Paris' law
Objavljeno: 10.07.2015; Ogledov: 1064; Prenosov: 22
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5. Micromechanical analysis of constraint effect on fracture initiation in strength mis-matched welded jointsMiloš Dobrojević, Marko Rakin, Nenad Gubeljak, I. Cvijović, Milorad Zrilić, N. Krunich, Aleksandar Sedmak, 2007, izvirni znanstveni članek Opis: In this paper the micromechanical approach to ductile fracture was applied in a study of constraint effect crack growth initiation in mismatched welded joints. The single edged- notched bend specimens (precrack length ▫$a_o/W=0.32$▫) were experimentally and numerically analysed. The coupled micromechanical model prposed by Gurson, Tvergaard and Needleman was used. Constraint effect was tested by varying widths of the welded joints (6, 12 and 18 mm). HSLA steel was used as the base metal in a quenched and tempered condition. The flux-cored arx-welding process in shielding gas was used. Two different fillers were selected to obtain over- and undermatched weld metal. The micromechanical parameters used in prediction of the crack growth initiation on precracked specimen were calibrated on a round smmoth specimen. The difference in fracture behaviour between over- and undermatched welded joints obtained in experimental results was followed by numerical computationsof void volume fraction in front of the crack tip.
Ključne besede: fracture mechanics, ductile fracture, high strength low alloyed steel, cracks, micromechanical model, mismatched welded joints, constraint effect, void growth
Objavljeno: 01.06.2012; Ogledov: 1428; Prenosov: 77
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