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Correlations of Mechanical Properties and Microstructure at Specific Zones of Welded Joint of High-Strength Low-Alloy Steels

Ivanović L., Marjanović V., Ilić A., Stojanović B., Lazić V.

Archives of Metallurgy and Materials

2018

Vol. 63, iss. 1

285--292

This paper presents experimental testing of the mechanical characteristics and properties of samples made of high-strength low-alloy steel with two different multi pass V grove butt welded joint. Two sample groups are tested: the root pass is made by manual metal arc welding process for the former and metal inert gas welding process for the latter. Other passes of those multi passes welded joints are made by metal active gas welding process. Further, the research included analyses of the experimentally obtained mechanical properties and load response of the samples in correlations to microhardness distribution and microstructural state at specific zones of the welded joints. Since both the chemical composition and microstructural state of high-strength low-alloy steel originate from special production processes their nature must be fully understood. Accordingly, the nature of the steels should directly impact not only the selection and definition of welding but the design process of mechanical constructions, too. From the practical aspect, mechanical characteristics and properties as well as load response of welded joints are crucial. But, sensitivity of those steels to inadequate welding technology and improper parameters or filler metal is high. On the other side, design codes and recommendations are not yet fully developed and precise. Results obtained in this research implicate that even small changes of welding technology causes the change of characteristics itself. Consequently, the steels development must be accompanied with the improvement of the welding processes and design modifications.

Modelling the trochoidal gearing with respect to the uniform teeth wear

Ivanović L., Josifović D., Devedžić G.

Tribologia

2009

nr 1

63-75

This paper presents a theoretical model of gearing with a modified trochoidal profile applied to Gerotor pumps. Gerotor pumps belong to the category of rotating machines whose kinematics is based on the principles of a planetary mechanism with internal gearing. Using geometrical and kinematical models of the trochoidal gearing, we provide a detailed analysis of specific sliding at the contact points of the profiles, as well as the relations for its determination. Specific sliding is one of the most significant constraining factors in the selection of the geometrical parameters of the gearing profile, which indicates conditions for appearing friction and wear of the tooth contact surface. The key objective in optimal gerotor pump design is to provide the appropriate selection of geometrical parameters of the gearing, leading to the uniform wear of meshing gears teeth profiles. This requires ensuring the uniform wear of meshing profiles at the point with highest value of sliding velocity, i.e. at the contact points most distant from the pitch point. Consequently, the methodology described in the paper defines the constraints to enable uniform wear of meshing gear teeth profiles from the kinematical point of view.

W referacie przedstawiono model teoretyczny zmodyfikowanego zazębienia trochoidalnego, które jest stosowane w pompach systemu Gerotor. Pompy Gerotor należą do maszyn wirujących, których kinematyka oparta jest na zasadzie mechanizmu planetarnego z zazębieniem wewnętrznym. Za pomocą modeli geometrycznych i kinematycznych przeprowadzono szczegółową analizę poślizgu względnego w punktach styku profili; podano też zależności do jego określenia. Poślizg względny jest jednym z najbardziej istotnych czynników spośród parametrów geometrycznych decydujących o warunkach tarcia i zużyciu kontaktujących się powierzchni. Zasadniczym zadaniem w konstrukcji pomp Gerotor jest właściwy dobór parametrów zazębienia dla uzyskania równomiernego zużycia w punkcie z największą prędkością poślizgu, tj. w punkcie najbardziej oddalonym od bieguna zazębienia. Metodologia przedstawiona w referacie umożliwia określenie warunków dla uzyskania równomiernego zużycia z punktu widzenia kinematyki.