This paper focuses on the characterization of the tabletting process and analysis one of the most common pharmaceutical excipients MCC Avicel PH102 by Heckel, Kawakita, Cooper-Eaton and Adams compaction equations. Experimental material was determined by measuring its parameters as particle size distribution, angle of wall friction and flow properties and for more detailed characteristics of the material particles, microscopy images of the powder before and after compressing were created.

The fibre laser welding of two different dual phase steels HCT980X and HCT600X was evaluated. The sheets with thickness of 1.2 mm were welded using the solid-state fibre laser IPG type YLR 4500 with maximum output 4.5 kW and wave length 1060 nm at graduated beam powers and welding speeds. The microstructure of welded samples was analysed, microhardness and tensile strength were measured. The heat input influenced the microstructure of the fusion zone and heat affected zone. The microhardness increased in the fusion zone and even more in the heat affected zone of HCT980X steel, which was the consequence of martensite and bainite formation in these areas. The tensile strength of joints achieved the strength of the HCT600X steel and all joints fractured in the HCT600X base metal.Keywords: dual phase steels, fibre laser welding, microstructure, microhardness, tensile strength IntroductionDual phase (DP) steels, which are the important part of advanced high strength steels, have been used in manufacture of lightweight automobiles to reduce fuel consumption without compromising other attributes such as safety, performance, recyclability and cost. Some of the major advantages of the dual phase steels include their superior mechanical properties in comparison with standard steels, moderate price thanks to small amount of alloying additions, as well as excellent technological properties, together with good weldability and machinability [1][2][3][4]. The excellent mechanical properties are the consequence of their multiphase structure. Microstructure of DP steel consists of 30-70 % martensite in the fine-grained, spherical ferrite matrix and 1-10 % of metastable retained austenite. As a result, the steel is characterised by high tensile strength up to 1180 MPa with unit elongation up to 27 %. Most often the microstructure of DP steel is developed as a result of accelerated cooling of thin sheets after cold rolling in the range between Ac1 and Ac3 and controlled air-water mist cooling to ambient temperature. The process is flexible one and allows for different combinations of relative volume ratio of ferrite and martensite. The dual phase steels are used in automotive industry for frames and crossbeams, vertical beams, side impact beams, and safety elements [4][5][6]. Dual phase steels have been used for producing of tailor welded blanks. Tailor welded blanks are semi-finished parts that consist of at least two single sheets that are welded together prior the forming process. The sheets can exhibit different mechanical properties, thickness or coatings.

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The effects of beam power and welding speed on microstructure, microhardnes and tensile strength of HCT600X laser welded steel sheets were evaluated. The welding parameters influenced both the width and the microstructure of the fusion zone and heat affected zone. The welding process has no effect on tensile strength of joints which achieved the strength of base metal and all joints fractured in the base metal.