Solid State Phenomena Vol. 199

Abstract: The article presents the research results of hardness values distribution of friction stir welded joint (FSW) alloy AW 7020 (AlZn5Mg1). FSW is a method of welding in the solid state, mechanical properties of joints welded by that method can be higher than that for arc welding techniques (MIG, TIG). The parameters of friction stir welding (FSW) used to join 7020 alloy were presented. Metallographic analysis showed the correctly structured FSW welded 7020 alloy. The study was carried out using Vickers hardness HV5 in accordance with the requirements of the Polish Standard PN-EN 6507 using a hardness testing machine HPO-10. The location of measurement points in the butt joint was determined in accordance with PN-EN 1043-1:2000. The indenter load was 49 N. In order to determine the effect of bonding method on structure change of the material microscopic examination was performed using an optical microscope ZEISS Axiovert 25.The test specimens were polished and then etched with KELLER reagent. This enabled the precise identification of zones present in the joint, such as: weld nugget, thermo-mechanically affected zone, native material. To determine the grain size in the different zones of joints bonded by FSW AxioVision 4.8.2 software was used. Hardness testing in across researched joints showed that the highest value of hardness is in the weld and the lowest is in the native material.

Abstract: In order to improve the quality of plates, an asymmetric rolling process can be introduced, which will help reduce the total roll separating force and increase plate flatness and decrease thickness deviations along the width and length of rolled strip [1÷.

Abstract: Lifetime of details directly influences lifetime of machines and equipments. Details in most cases wear out, instead of collapse. Raise of their wear resistance is a perspective problem. The most economic way is drawing hard-wearing coverings on a surface of the details made of steel. In our work coverings from oxide ceramics (Al₂O₃ and Al₂O₃+TiO₂) coatings, covered by gas-flame spraying on a surface of the specimens made from tool steels 105WCr6 were investigated. Before a conversion coating specimens were hardened and tempered, the surface was exposed to sandblasting, and the special sub layer for raise of an adhesion of a covering with a basis was put. After drawing a ceramic covering micro hardness of a covering and a basis was measured. Then it was tested contact and abrasive wear resistance of surfaces on original installations. It is resulted and circuits a technique of research of wear resistance. Agency on wear resistance of an aspect oxide ceramics, type of wear contact and abrasive, heating of the superficial layer arising because of a friction of two surfaces is investigated. At the end of work leading-outs and are presented to the recommendation on application oxide ceramics to increase of wear resistance of steel details.

Abstract: Measurement results of 92W-5Re-3Ni and 77W-20Re-3Ni sinters produced from powders spheroidized in a plasma jet are presented in the paper. The production process is described, typical microstructures are presented, and the analysis of chemical composition in selected microregions of the samples have been performed. Additionally, a comparison of selected properties of materials produced from powders spheroidized in plasma and from non-modified powders is shown.

Abstract: A considerable increase in interest in using corrosion resistant steel clad ribbed bars in the construction industry has been observed in recent years. This is owing to the particular properties of these bars, namely high durability and rigidity, good mechanical properties, and high corrosion resistance. Bimetallic ribbed bars can be manufactured in medium-size and small shape mills from previously produced bimetallic feedstock. The manufacture of ribbed bars with an outer layer of corrosion-resistant steel is a complicated process that involves numerous technological problems. The most important of which include the obtaining of bimetallic feedstock with the adequate strength of the bond in the region of junction between the core and the clad layer, and assuring the even plastic flow of both bimetallic layers during the process of rolling in the elongating and forming passes in the shape Mill. Failure to meet these conditions may result in a delamination of the bimetallic band during rolling or the formation of other defects, which will disqualify the finished bimetallic bar [1÷4]. In the paper the metallographic analysis of bimetallic ribbed bars steel-steel resistant to corrosion produced from bimetallic feedstock mill of the surfacing method TIG and of the method ESS LM received. Surfacing method TIG and ESS LM method are the affirmed processes the receipt the bars plated is characterizing the large strength of bond two different metals. Moreover, in this study, the authors present the bond strength of interface of bimetallic joint of the cross section on the test bar. The core was of the constructional carbon steel C45E and the clad layer was made of the corrosion resistant steel X2CrNi18-10. Plastometric tests were performed on a Gleeble 3800 plastometer owned by the Institute of Modelling and Automation of Plastic Working Processes, using strain rates of 0.1 s^-1, 1.0 s^-1 and 10 s^-1 respectively [1÷3, 7].

Abstract: The aim of the paper is to analyse how different mechanical properties of bonded metals influence the cyclic behaviour of bimetallic components. The simulations also include different initial state of stress since one of the methods for manufacturing bimetals is explosive welding which introduces residual stresses into bonded materials. The analysed cyclic behaviour concerns cyclic stress-strain relation in elastic-plastic strain state. The multi-surface plasticity model of Mróz-Garud was applied. Results shows that depend on residual stresses the ratchetting phenomena could occur.

Abstract: This paper concerns the possibility of use of the Jiles-Atherton-Sablik extended model to describe the magnetic characteristics for construction steel ST3. Result of the modelling utilizing extended Jiles-Atherton-Sablik model are in good agreement with results of experimental measurements for magnetic hysteresis loops B(H). However experimental results indicated, that the influence of temperature on B(H) characteristics is relatively small and can be neglected from the point of view of modelling for technical applications, such as stress estimation for non-destructive testing.

Abstract: In this work, a rolling schedule has been developed, which allows the scrapped S60 railway rail to be used for further processing into semi-finished or finished products. The main purpose of the investigations was to develop the shape and dimensions the rolling grooves and to select the strains in various passes in the ploughshare rolling process. The main problem during roll pass design was the ploughshare shape which is asymmetric and has a varying thickness along the width. The developed roll pass design consist of five passes: one open shape pass, one edging pass and three closed shape passes. The first open shape pass is characterized by an unusual shape which tends to reduce the band asymmetricality in the horizontal axis in such a manner as to prevent the formation of lapping in the sharp corner areas resulting from cutting. Based on the numerical modelling it has been found that the developed roll pass design allows the production of a ploughshare of dimensions conforming to the dimensional assumptions. For the numerical modelling of the rolling process, the Forge2008® computer program was employed.

Abstract: The paper presents results of the numerical modelling of the plates accelerated cooling process after the rolling process. Research were carried out for one of the plate rolling mill technological conditions. Presented in the paper research were done for a few variants for X70 steel grade. As a result of the carried out research temperature distribution on the cross section of the cooled plates for the analyzed variants of the accelerated cooling process were obtain.

Abstract: The research presented in the current paper was carried out for the experimental steel designed for plate which meets the requirements for grade X100 according to API5L. Physical modeling of the rolling process was carried out using the GLEEBLE 3800 simulator. The tested steel is fine-grained constructional steel for making tubes for gas pipelines with the working pressure higher than 15 MPa. The fine-grained structure guarantees excellent plastic properties as well as high impact toughness. After rolling the steel should obtain the minimal yield point of 690 MPa and tensile strength over 760 MPa.