The paper presents research results on the quality of hardfacing layers made during the renovation of unheated mold surfaces designed for injection of aluminum alloys using the plasma transferred arc (PTA) technology. As mold material, the medium alloy steel X38CrMoV5-1 (H11) was used. For the formation of functional layers, three types of additives in the form of powder were applied: two types on an iron basis with the designation HSS 23 and HSS 30 and one type on a nickel basis with the designation DEW Nibasit 625-P. The hardfacing layers were made on a 120 × 350 × 50 mm plate in two layers on the plasma hardfacing machine PPC 250 R6. The quality of the layers was evaluated by means of nondestructive and destructive tests. The surface integrity of the layers was assessed using visual and capillary tests. The samples passed these tests. The impact of the parameters used and the mixing of the hardfacing metal with base material, as well as the structure analysis, were assessed by means of light and electron microscopy (SEM). The chemical composition of the elements was determined by energy-dispersive X-ray spectroscopy (EDX) analysis using a SEM microscope. The hardness of the individual layers was evaluated. Since, during operation, molds are subjected to significant wear due to friction, the friction coefficients for selected temperatures were determined by the equipment for the evaluation of tribology properties. Based on the experiments conducted, all three types of additives can be used for renovation. However, from a tribology perspective, the additive DEW Nibasit 625-P on a nickel alloy basis is recommended for renovation.

The paper deals with assessment of influence of welding time on welding joint creation. Diffusion welding method in inert gas (Ar 4.8) at low pressure was used. Homogenous welding joints were created from steel E296 (according to EN ISO 10025-2). Homogeneous welds were done for easy assessment of influence of diffusion welding time and temperature on resulting welding interface, which was closely observed. Due to diffusion of carbon and manganese, on the joint interface were created complex iron and manganese carbides (FeMn)3C. It was found that the amount of created carbides depended on temperature and time. At temperature 1000°C the biggest quantities of carbides were created, already at time 900 s the continuous carbidic strip was created with thickness 1-2μm. This strip is very brittle and is detrimental to joint properties

The research focuses on verification of FEM simulation of GMAW bead on plate welding with experimental results. In the program Visual Environment simple FEM simulation of GMAW bead on plate welding on Al alloy EN AW 7022 was created and these ...

Titanium is material which is used in many areas of human activity. Therefore it is necessary to join it with other material. It is very difficult to welding Ti with other metals by conventional fusion welding methods. There exist special joining technologies of heterogeneous materials which is possible to use. This is usually a joining of materials in the solid state, as diffusion welding, friction welding or explosion welding. This contribution deals with diffusion welding of titanium alloy Ti6Al4V and stainless austenitic steel 1.4301. There are described mechanical properties (as is reduced modulus Er and indentation hardness HIT) and changes of chemical composition of join due to diffusion of elements.