This article deals with the non-destructive ultrasonic testing of split sleeve butt joints by ultrasonic methods. Split sleeve is used to repair gas pipelines with gas leakage. The new ultrasonic methods TOFD and Phased Arrays are compared considering to the selected butt weld configuration. To compare testing methods, ES Beam Tool software was used to prediction of ultrasonic beam spread through weld joint. TOFD technology was selected to butt weld section testing according to the beam spread simulation results. The results of ultrasonic testing by TOFD method were compared with results of macrostructural analysis of weld joint. Controlling the suitability of testing method to planar defect identification, the artificial defects were prepared and tested. The appropriate setting of measuring technique can be predicted from experimental results.

In this paper, the experimental investigation results of the bead sequence input on geometry, structure, and hardness of surfaced layers after multi-pass weld surfacing are analyzed. Three S355 steel plates surfaced by GMAW (Gas Metal Arc Welding) were tested with three different combinations of six beads. The geometric, structural, and hardness analysis was carried out in the cross-section of the plates in the middle of the welded layers. The dimensions of padded layers, fusion and heat-affected zone, as well as the individual padded weld were evaluated. On the basis of metallographic samples, qualitative and quantitative structure analysis was performed. Hardness measurements in surfacing welds and heat-affected zones in the tested cross-sections of the surfacing layers were carried out. A comparative analysis of structure and hardness, taking into account the thermal implications of the bead sequence, allowed for the formulation of conclusions. Comparative studies have shown differences in properties between heat-affected zones (HAZ) for individual surfacing sequences. These differences were mainly in the dimensions of the surfacing layers, the share of structural components, as well as the uniformity of hardness distributions. Finally, the most favorable sequence in terms of structure and hardness distribution, maximum hardness, and range of hardness has been indicated.

The article deals with ultrasonic testing possibilities of the copper alloy centrifugal casts. It focused on the problems that arise when testing of castings is made of non-ferrous materials. Most common types of casting defects is dedicated in theoretical introduction of article. Ultrasonic testing technique by conventional ultrasound system is described in the theoretical part too. Practical ultrasonic testing of centrifugal copper alloy cast - brass is in experimental part. The experimental sample was part of centrifugally cast brass ring with dimensions of Ø1200x34 mm. The influence of microstructure on ultrasonic attenuation and limitations in testing due to attenuation is describes in experimental part. Conventional direct single element contact ultrasound probe with frequencies of 5 MHz, 3.5 MHz and 2 MHz were used for all experimental measurements. The results of experimental part of article are recommendations for selecting equipment and accessories for casting testing made of non-ferrous metals.

Article deals with ultrasonic testing of the casting. It focuses on the problems that arise when testing of castings is made of non-ferrous metals. Theoretical introduction of article is dedicated to the most common types of casting defects and selecting technology for their reliable identification. The impact of the large anisotropic grain casting to propagate and attenuation of ultrasound it describes in theory. The examples of practical testing of Cu-alloy casting are presented in experimental part. Modern tools for simulation of ultrasound propagation in testing material were used for the correct setting techniques of UT testing as well as for the evaluation of the measurement results. Conventional direct contact ultrasound probe with frequencies of 5 MHz, 3.5 MHz and 2 MHz were used for all measurements. The results of experimental measurements referred in this article are recommendations for selecting equipment and accessories for casting testing made of non-ferrous metals.

The article summarizes the theoretical knowledge from the field of brazing of graphitic cast iron, especially by means of conventional flame brazing using a filler metal based on CuZn (CuZn40SnSi -brass alloy). The experimental part of the thesis presents the results of performance assessment of brazed joints on other than CuZn basis using silicone (CuSi3Mn1) or aluminium bronze (CuAl10Fe). TIG electrical arc was used as a source of heat to melt these filler materials. The results show satisfactory brazed joints with a CuAl10Fe filler metal, while pre-heating is not necessary, which favours this method greatly while repairing sizeable castings. The technological procedure recommends the use of AC current with an increased frequency and a modified balance between positive and negative electric arc polarity to focus the heat on a filler metal without melting the base material. The suitability of the joint is evaluated on the basis of visual inspection, mechanic and metallographic testing.

The present article is focused on the non-destructive testing (NDT) inspection of pipelines during operation namely Magnetic Flux Leakage (MFL) method and Phased Array ultrasonic (PA) method. MFL inspection technique is electromagnetic test method primarily used to detect flaws or defects in high-permeability of ferromagnetic metals such as carbon steel tubing, plate, wire rope and tubular parts. PA ultrasonic method is an advanced NDT method that is used to detect component failures i.e. cracks or flaws and thereby determine component quality. Due to the possibility to control parameters such as beam angle and focal distance, this method is very efficient regarding to the defect detection and speed of testing. In this article real pipeline defect was identified by MFL method in the internal pipe inspection. This defect was fully mapped by Phased Array ultrasonic method in the terrain. 3D model of defect in the tested material was created from measured data and obtained by PA method. The real dimensions of the defect determined from measurements by the method of MFL and PA are compared.

NUMERICAL SIMULATION OF DISSIMILAR WELD JOINT IN SYSWELD SIMULATION SOFTWARE Radoslav Koňár, Marek PatekOriginal scientific paper Dissimilar weld joints are prone to frequent failures caused by many factors. Several methods might be used for prediction of the failures, from which prediction of the residual stresses and weld joint hardness plays a very important role. During the construction design, there is a possibility to predict residual stress by welding numerical simulation that may serve as the failure prevention. In presented article, residual stresses of dissimilar X5CrNi18-10/S355J2H weld joint were predicted by SYSWELD software after optimization of welding process by experimentally obtained thermal behaviour. The hardness wizard tool of the programme was employed for prediction of the weld joint hardness. Keywords: dissimilar weld; hardness prediction; residual stress; SYSWELD; temperature fieldNumerička simulacija zavarenog spoja od različitih materijala u simulacijskom programu SYSWELD Izvorni znanstveni članak Zavareni spojevi od različitih materijala podliježu čestim kvarovima zbog raznih faktora. Postoji nekoliko metoda koje se mogu primijeniti za predviđanje kvarova, a među njima vrlo važnu ulogu ima predviđanje zaostalih naprezanja i tvrdoće zavara. Tijekom dizajniranja konstrukcije, postoji mogućnost predviđanja zaostalog naprezanja numeričkom simulacijom varenja koja može služiti za prevenciju kvara. U ovom radu zaostala naprezanja zavarenog spoja X5CrNi18-10/S355J2H od različitih materijala predviđena su programom SYSWELD nakon optimizacije postupka zavarivanja eksperimentalno dobivenim toplinskim ponašanjem. Čudesni alat za tvrdoću iz tog programa upotrjebljen je za predviđanje tvrdoće zavarenog spoja.Ključne riječi: predviđanje tvrdoće; SYSWELD; temperaturno područje; zaostalo naprezanje; zavar od različitih materijala

The calculation results of the temperature field during multi-beads GMAW (Gas Metal Arc Welding) cladding of the S355 steel plate are presented in the paper. Numerical simulations were performed using the Sysweld ® program. Two of Goldak's heat source models were chosen for calculating the temperature field for each weld bead. The original article achievement is, by selecting the right heat source model and heat loading of the finite elements, obtaining an irregular shape of the fusion zone. This irregular shape of the fusion zone is very complicated to obtain using other commercial programs for numerical welding simulation. The calculation results were verified by the dimensions (critical temperatures) of the heat affected zones (HAZ) determined in the experiment, obtaining a satisfactory agreement.