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The research carried out by the authors of this paper is focused on the technological process of Inconel 625 welding with the MAG–CMT (Metal Active Gas-Cold Metal Transfer) method. Inconel 625 was welded to the substrate material, which was 16Mo3 steel. Both materials are used to produce the so-called bimetallic tubes, which in practice serve as a part of the equipment intended for waste incineration. For this reason, the bimetallic tubes must withstand extreme conditions during their operation. Therefore, bimetal pipes are highly stressed composite components that must resist corrosion in a chemically aggressive environment. For this reason, an extensive material and technological analysis of the production of pipe bends with a supercritical bend of 0.7D from bimetal pipes with Inconel 625 cladding was performed. In the welding process, the authors investigated the possibilities of the CMT method with and without using the oscillating movement of the welding head. The most important factor in deciding which method would be appropriate was to measure the amount of iron on the surface of the coating layer. The authors' paper builds on the authors' previous research in this area, which was mainly focused on research on the critical bending of bimetallic tubes. [ABSTRACT FROM AUTHOR]

Drilling into the solid material is one of the basic technological operations, which creates a cylindrical hole in an appropriate time with required quality. Drilling operation demands a favourable removal of chips from the cutting area because a creation of an undesirable shape of chips can impart a lower quality of the drilled hole corresponding with the generation of excess heat due to the intense contact of the chip with drill. The solution for a proper machining is a suitable modification of the drill geometry i.e., point and clearance angles as presented in current study. The tested drills are made of M35 high-speed steel characterized by a very thin core at the point of the drill. An interesting feature of the drills is the use of cutting speed higher than 30 m min−1, with the feed of 0.2 mm per revolution. The surface roughness (Ra and Rz lower than 1 µm and 6 µm respectively), cylindricity (0.045 mm), roundness (0.025 mm), perpendicularity of the hole axis (0.025 mm), diameters and position of the individual holes were achieved for a drill with point angle 138.32°and clearance angle 6.92 respectively. The increase of the drill point angle by 6° resulted in the decrease in the feed force of more than 150 N. In addition, an increase of the clearance angle by 1° resulted with a decrease in the feed force of 70 N. The results of the experiment showed that with the correct geometry of the tool the effective machining without using internal cooling can be realised. [ABSTRACT FROM AUTHOR]