This article presents the research results on the production of laser-cladded Inconel-625 in situ composite coatings on the S355JR substrate by addition of titanium and graphite powders to pure ...Inconel 625 alloy powder mixture for increased hardness and erosive wear resistance of the coatings. The research featured in the article includes penetrant testing, macro-, and microscopic observations of produced coatings, phase and chemical composition analysis, hardness and solid particle erosion tests. The results showed that the addition of titanium and graphite powders resulted in the composite microstructure formation by precipitation of Ti, Nb, Mo, and C-rich blocky and eutectic particles during crystallization. The conducted tests revealed that the microstructure change resulted in an increase in hardness and erosive wear resistance by 27% and 30%, respectively.
The article presents research results on the possibility of shaping the structure and properties of Co-Cr-W-C-Ti alloys (type Stellite 6) using laser cladding technology. Cobalt-based alloys are used ...in several industries because they are characterized by high erosion, abrasion, and corrosion resistance, retaining these properties at high temperatures. To further increase erosion resistance, it seems appropriate to reinforce material by in situ synthesis of hard phases. Among the transition metal carbides (TMCs), titanium carbide is one of the hardest and can have a positive effect on the extension of the lifetime of components made from cobalt-based alloys. In this article, concentration of C, W, and Ti due to the possibility of in situ synthesis of titanium carbides was subjected to detailed analysis. The provided research includes macrostructure and microstructure analysis, X-ray diffraction (XRD), microhardness, and penetrant tests. It was found that the optimal concentrations of Ti and C in the Co-Cr-W-C alloy allow the formation of titanium carbides, which significantly improves erosion resistance for low impact angles. Depending on the concentrations of titanium, carbon, and tungsten in the molten metal pool, it is possible to shape the alloy structure by influencing to morphology and size of the reinforcing phase in the form of the complex carbide (Ti,W)C.
Assessing the temperature of the joint in on-line mode is a vital task that is demanded to characterize the formations of terns formations that are taking place in a joint and result in reaching ...necessary properties of the joint. Arc welding generates a high amount of heat that is reflected by the metallic surface of the welded object. In the paper, a temperature measurement credibility increase method is described and evaluated. The proposed method is used to reduce the influence of the reflected temperature of the hot torch and the arc on the temperature distribution observed on the surface of the welded joint using an infrared camera. The elaborated approach is based on comparison between infrared observation of the solidifying weld and precisely performed finite element method (FEM) simulation. The FEM simulations were calibrated according to the geometry of the fusion zone. It allows to precisely model heat source properties. The best-reflected temperature correction map was selected and applied to obtain a temperature representation that differs from the FEM baseline by less than 10 °C. Precise temperature values allowed us to cluster welded joints in 3D feature space (temperature, hardness, linear energy). It was found that by using the k-means clustering method it is possible to distinguish between correct and faulty (in terms of too low mechanical properties) joints.
Thermomechanically processed steels are materials of great mechanical properties connected with more than good weldability. This mixture makes them interesting for different types of industrial ...applications. When creating welded joints, a specified amount of heat is introduced into the welding area and a so called heat-affected zone (HAZ) is formed. The key issue is to reduce the width of the HAZ, because properties of the material in the HAZ are worse than in the base material. In the paper, thermographic measurements of HAZ temperatures were presented as a potential tool for quality assuring the welding process in terms of monitoring and control. The main issue solved was the precise temperature measurement in terms of varying emissivity during a welding thermal cycle. A model of emissivity changes was elaborated and successfully applied. Additionally, material in the HAZ was tested to reveal its properties and connect changes of those properties with heating parameters. The obtained results prove that correctly modeled emissivity allows measurement of temperature, which is a valuable tool for welding process monitoring.
" One of the most commonly used corrosion resistant construction materials are austenitic stainless steels, mainly AISI 304. Any deviation from the welding technology in the case of this steel may ...result in welding defects or even loss of corrosion resistance. The purpose of this work was explored the influence of remelting using the TIG method (141) on the properties and structure of welded joints of AISI 304. The scope of this paper included making test joints of 2 mm thick sheets and then remelting them. The further part of this work consisted in carrying out: mechanical, macroscopic and microscopic examinations, hardness and corrosion resistance tests, SEM/EDS analysis. As a result of tests it was found that remelting of a joint causes a significant increase in hardness, lower elongation and general corrosion resistance, but increases the resistance to intercrystalline corrosion. Flexural strength and tensile strength were not changed by remelting."
The thermal conditions in the molten pool during the laser surface melting of ductile cast iron EN-GJS-700-2 were estimated by using infrared thermography and thermocouple measurements. The thermal ...data were then correlated with the microstructure of the melted zone. Additionally, the thermodynamic calculations of a Fe-C-Si alloy system were performed to predict the solidification path of the melted zone. It was found that increasing the cooling rate during solidification of the refined ledeburite eutectic but also suppressed the martensitic transformation. A continuous network of plate-like secondary cementite precipitates and nanometric spherical precipitates of tertiary cementite were observed in regions of primary and eutectic austenite. The solidification of the melted zone terminated with the Liquid → γ-Fe + Fe
C + Fe
Si
C reaction. The hardness of the melted zone was affected by both the fraction of the retained austenite and the morphology of the ledeburite eutectic.
The article presents the research in the field of production of metal–matrix composite coatings using laser cladding technology. The general purpose of producing composite coatings is the improvement ...of wear resistance of the material surface. In this research, Inconel 625 was used as a matrix material. Nickel-based superalloys are used in several industries for unique applications because they possess a number of beneficial properties including high tensile and fatigue strengths and resistance to high-temperature corrosion in aggressive environments. However, for some applications, this alloy shows insufficient wear resistance of the surface; therefore, for the tests, Inconel 625-based composite coatings were produced with the addition of 10 vol.%, 20 vol.%, and 40 vol.% of titanium carbide (TiC) particles as reinforcement. In general, the addition of TiC particles had a positive effect on the erosion resistance of the surface. The aim of the current research was to test the influence of TiC particle reinforcement of Inconel 625 laser-cladded coatings on corrosion resistance of the surface. For the tests, the laser-cladded composite coatings with uniform phase distribution were produced. The proceeded tests included penetrant tests, macrostructure and microstructure analysis, X-ray diffraction (XRD), and microhardness and corrosion resistance tests. The results showed that using laser cladding, TiC-reinforced Inconel 625 uniform composite coatings may be produced. The addition of TiC particles caused microstructure changes in the Inconel 625 matrix and an increase in hardness. The addition of TiC particles had a negative influence on Inconel 625 corrosion resistance, but with the increased composite coating homogeneity, the corrosion resistance improved.
Presented in this work are the properties and structure characteristics of MMA (Manual Metal Arc) deposited nanocrystalline coatings (Fe-Cr-Nb-B) applied to an iron nanoalloy matrix on an S355N steel ...substrate in relation to selected construction materials resistant to abrasive wear currently used in industry. The obtained overlay welds were subjected to macro and microscopic metallographic examinations; grain size was determined by X-ray diffraction (XRD), and chemical composition of precipitates was determined by energy-dispersive X-ray spectroscopy (EDS) during scanning electron microscopy (SEM). The size of the crystalline grains of the Fe-Cr-Nb-B nanocrystalline microstructure was analyzed using an Xpert PRO X-ray diffractometer. Analysis of the test results of the obtained layers of arc-welded Fe-Cr-Nb-B-type alloy confirmed that the obtained layers are made of crystallites with a size of 20 nm, which classifies these layers as nanocrystalline. The obtained nanocrystalline coatings were assessed by hardness and with the use of metal-mineral abrasion testing. The results of the coatings' properties tests were compared to HARDOX 400 alloy steel.
The article presents the results of the laser alloying process of a ductile cast iron EN-GJS 350-22 surface with titanium powder in nitrogen atmosphere. The aim of this research was to test the ...influence of nitrogen atmosphere on the structure and properties of the ductile cast iron surface layer produced by a laser alloying process with titanium. The laser alloying process was conducted using a Rofin Sinar DL020 2 kW high-power diode laser (HPDDL) with rectangular focus and uniform power density distribution in the focus axis. The tests of the produced surface layers included macrostructure and microstructure observations, X-ray diffraction (XRD) analysis, energy-dispersive spectroscopy (EDS) on scanning electron microscope (SEM) and transmission electron microscope (TEM), Vickers hardness and solid particle erosion according to ASTM G76-04 standard. As a result of the laser alloying process in nitrogen atmosphere with titanium powder, the in situ metal matrix composite structure reinforced by TiCN particles was formed. The laser alloying process of ductile cast iron caused the increased hardness and erosion resistance of the surface.
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