POSSIBILITIES OF RENOVATION FUNCTIONAL SURFACES OF EQUIPMENTS IN THE MECHANICAL ENGINEERING INDUSTRY

The paper analyzes the possibilities of increasing the lifespan of rollers in continuous steel casting line. There are analyzed the causes of the surface rollers damage and the impact of degrading factors in metallurgical production. Three types of welding consumable electrodes designed for restoration layers formation applied by SAW surfacing technology were analyzed. There were analyzed microstructure, microhardness and properties of weld clads in tribological conditions

Investigation of Applicability Flowdrill Technology for Joining Thin-Walled Metal Sheets

The applicability of flowdrill technology to join steel and aluminum alloys is studied. When used to flowdrill two overlapped thin-walled materials, a joint is formed as a secondary effect. The quality of the resulting bushings forming the interference fit joint was investigated by metallography. The joints were formed using a combination of uncoated deep drawn steel, galvanized high-strength low alloy steel and aluminum alloy, in different positions in the joint. Subsequently, tensile shear testing of single joints was performed. The load-carrying capacity of the joints was also tested in combination with adhesive bonding. The combination of both technologies yields an increase in the dissipated energy of the joint at failure. The bonded connection provides a high maximum force at failure, the mechanical connection through bushings leads to an increase in the displacement value at failure, thereby increasing the area under the loading curve. The DC-Al joint showed the highest load-carrying capacity, up to 9 kN, as well as dissipative energy, up to 10.3 J. The joints were fractured by shearing of the inner bushing under tensile stress. The failure surfaces exhibited a typical ductile character with dimpled morphology. It was found that from the point of view of the load-carrying capacity of the joint, it is advisable to place a material with a higher melting temperature in the upper position in the joint. The combination of flowdrill technology with adhesive bonding results in a sealed joint with high load-bearing capacity, reduction in the risk of crevice and galvanic corrosion

THE WEAR OF INJECTION MOULD FUNCTIONAL PARTS IN CONTACT WITH POLYMER COMPOSITES

The paper deals with the evaluation of material wear of injection moulds made of aluminium alloy Alumec 89 and copper alloy Moldmax HH in friction couples with plastomer materials with various filler contents. The friction relations in injection moulding were simulated in an adhesion dry wear test using an Amsler machine, with an area contact of the friction couple materials. The wear intensity was evaluated by determination of friction coefficient and relative wearing by the mass loss. Surface morphology changes of evaluated alloys after wear and the thermal conditions in particular friction couples were analysed simultaneously

Surface Characterization after Blasting

Blasting modifies the surface state of materials in terms of surface irregularities too. Bearing in mind that the roughness characteristics affect the components functionality, it is essential to study and evaluation the surface state of pretreated materials. The chapter deals with evaluation of relation between individual surface roughness parameters of the blasted surfaces based on the measured values on the surfaces, which were blasted by various types of blasting materials. Based on the analysis of the results were also proposed sets of surface roughness parameters, which can be used in the assessment of the blasted surfaces. These allow you to effectively distinguish differences in roughness of blasted surfaces from the point of view of other follow-up technologies. It also lists the main factors that affect surface roughness

Deformation and energy parameters of fracture of steel of the main gas pipeline

By example of steel 17G1S, the regularities in the impact fracture of Charpy specimens at normal and low temperatures are described. The relationship between the energy parameters of fracture (impact toughness) and the deformation response of the material (the height of shear lips) of the specimens from the pipe steel is established. The micromechanisms of impact fracture of the material are described. At 20 °C and –30 °C, focal splitting of the material was observed on the fracture surface of specimensat –60 °C, the material failed in a brittle manner by the mechanism of cleavage

General Regression Model for Predicting Surface Topography after Abrasive Blasting

Abrasive blasting modifies the surface state of pre-treated materials in terms of surface irregularities. Bearing in mind that the roughness characteristics affect the components functionality, it is essential to study and evaluation the surface state of pre-treated materials. The paper deals with evaluation of relation between individual parameters of roughness of the blasted surfaces by the correlation analysis. Based on the measured values on the surfaces which were blasted by various types of blasting devices, the correlation matrix was set and the standard of statistic importance of correlation between the monitored parameters was determined from it. The correlation coefficient was also set. There were found regression models using ANOVA (ANalysis Of Variance). Based on the analysis of the results were also proposed sets of roughness parameters, which can be used in the assessment of the blasted surfaces

Influence of the Hardfacing Welds Structure on Their Wear Resistance

The contribution presents the research results of hardfacing metals’ resistance in conditions of abrasive wear. Two types of hardfacing electrodes with a different chemical composition were used in the creation of three layers of hardfacing metals. The chemical composition of electrodes determines the difference in a hardface deposit structure. We have investigated the influence of mixing the base metal and a filler metal and the influence of hardfacing welds structure on the resistance against abrasive wear. The results of the experiments have showed that the intensity of wear is very dependent on the parameters of wear as well as the morphology structure of hardfacing metals

Study of Selected Properties of Thermally Sprayed Coatings Containing WC and WB Hard Particles

The paper presents results of research of the essential characteristics of two kinds of advanced coatings applied by HVOF technology. One studied coating: WB-WC-Co (60-30-10%) contains two types of hard particles (WC and WB), the second coating is eco-friendly alternative to the previously used WC-based coatings, called “green carbides” with the composition WC-FeCrAl (85-15%). In green carbides coating the heavy metals (Co, Ni, NiCr) forming the binding matrix in conventional wear-resistant coatings are replaced by more environmentally friendly matrix based on FeCrAl alloy. On the coatings was carried out: metallographic analysis, measurement of thickness, micro-hardness, adhesion, resistance to thermal cyclic loading and adhesive wear resistance (pin-on-disk test). One thermal cycle consisted of heating the coatings to 600°C, dwell for 10 minutes, and subsequently cooling on the still air. The number of thermal cycles: 10. The base material was stainless steel AISI 316L, pretreatment prior to application of the coating: blasting with white corundum, application device JP-5000

Microstructure, Wear Behavior and Corrosion Resistance of WC-FeCrAl and WC-WB-Co Coatings

The paper is focused on investigating the quality of two grades of thermally sprayed coatings deposited by high-velocity oxygen fuel (HVOF) technology. One grade contains WC hard particles in an environmentally progressive Ni- and Co-free FeCrAl matrix, while the second coating contains WC and WB hard particles in a cobalt matrix. The aim of the experimental work was to determine the effect of thermal cyclic loading on the coatings’ resistance to adhesive, abrasive and erosive wear. Abrasive wear was evaluated using abrasive cloth of two grit sizes, and erosive wear was evaluated by a dry-pot wear test in a pin mill at two sample angles. Adhesion wear resistance of the coatings was determined by a sliding wear test under dry friction conditions and in a 1 mol water solution of NaCl. Corrosion resistance of the coatings was evaluated using potentiodynamic polarization tests. Metallographic cross-sections were used for measurement of the microhardness and thickness and for line energy-dispersive X-ray (EDX) analysis. The tests proved the excellent resistance of both coatings against adhesive, abrasive, and erosive wear, as well as the ability of the WC-WB-Co coating to withstand alternating temperatures of up to 600 °C. The “green carbide” coating (WC-FeCrAl) can be recommended as an environmentally friendly replacement for Ni- and Co-containing coatings, but its operating temperature is strictly limited to 500 °C in air

Modification of surface morphology of Ti6Al4V alloy manufactured by Laser Sintering

The paper deals with the evaluation of relation between roughness parameters of Ti6Al4V alloy produced by DMLS and modified by abrasive blasting. There were two types of blasting abrasives that were used – white corundum and Zirblast at three levels of air pressure. The effect of pressure on the value of individual roughness parameters and an influence of blasting media on the parameters for samples blasted by white corundum and Zirblast were evaluated by ANOVA. Based on the measured values, the correlation matrix was set and the standard of correlation statistic importance between the monitored parameters was determined from it. The correlation coefficient was also set