This paper presents the results of voluminous experimental investigations conducted to analyze the influence of the welding procedure on the performance of regenerated gears. Cylindrical spur gears were tested, both newly manufactured and regenerated, in two fundamentally different ways: by hard facing (surfacing) with the “hard” filler metal (DUR 600-IG) and with the “soft” filler metal (EVB2CrMo) with subsequent cementation and quenching. The regeneration procedures were defined and executed, while, subsequently, the microstructure and microhardness of the hard-faced layers were established and measured, followed by checking the durability of the hard-faced teeth flanks. Finally, techno-economic analysis was performed to establish the rationality of the conducted regenerations, i.e., the costs of regenerated and newly manufactured teeth were compared. Based on the results of the conducted investigations, it was possible to establish the influence of the welding type on the performance characteristics (primarily the service life) of the regenerated gears. For individual reparatory hard facing, the procedure with the “hard” filler metal exhibited better characteristics, while for batch reparation of numerous damaged gears, the reparation with the “soft” filler metal, followed by cementation and heat treatment, might be more convenient.

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New way for defining of main process parameters procedure in the strip ironing process with double side thinning, as well as appropriate experimental results are presented in this paper. Given is improved analysis for friction coefficient and contact pressure defining. Classical common so called "Schlosser model" and other similar models are not suitable in certain cases, and give unreal values for both of main process parameters. Expressions obtained here were verified in suitable examples which are, also, presented in the paper. Verification was performed on the base of experimental results. Realized was the single and four phases ironing process of mild steel DC04 in sheet stripes drawing test. Stripes were 20 mm wide and 2.5 mm thick. Lateral force intensities were 5, 10 and 15 kN. Maximal obtained thinning deformation in one phase was about 17 %. Appropriate lubrication with mineral oil and grease was used in conditions of lower speed of 20 mm/min. Results shows that proposed improved procedures enables more precise process monitoring and precise quantification of lateral force, contact pressure and thinning strain influence on friction.

FSW is a solid-state joining process. It is widely used for joining hard alloys like steel, titanium, and aluminium which are very difficult to join by fusion welding. FSW joint quality is mainly influenced by shoulder and pin geometry, its diameter, tool material, tool rotation speed, and linear traveling speed. The paper presents a brief overview of the tools used during the FSW procedure. The influence of the tool pin on the material flow and mixture was analysed in detail. In addition, the primary and secondary material flow and how it is affected by the shape and dimensions of the tool pin are also discussed.

Purpose The purpose of this paper is to point out the possibilities for friction welding of dissimilar steels which are used in various industries. In addition, friction welding is a welding method that is applied for executing the very responsible joints. This research is focused on friction and tribological processes in the friction plane of the two pieces during the welding. Design/methodology/approach The present study research has been conducted based on the experimental testing of cylindrical specimens and results are analyzed. Findings The austenite grain size is affected by several factors through the friction process phase and the compacting phase during the welding. The very fine grain is the consequence of the high degree of the plastic deformation of the near-the-contact layers even in the friction phase. The viscous layer, which is formed during the stable friction phase, is the area where the moving of matter occurs according to a very complex mechanism. Originality/value The paper contains useful results from the area of conventional friction welding of dissimilar steels and it can be very useful to researchers and engineers who deal with similar problems.