No abstract

No abstract

The Friction Hydro-Pillar Process (FHPP) is an innovative process that has been recently studied regarding its possible in situ repair applications. There is still no literature about usage of the FHPP on duplex stainless steel (DSS) base materials to smaller forces than 25 kN. The investigation on DSS processing is crucial due his wide variety of critical uses in pipes and storage structures applied in chemical industry plants, where usual welding processes may lead to safety concerns. The aim of this study is to qualify the processing of SAF 2205 (UNS 31803) duplex stainless steel welded joints using FHPP as feasible repair procedure. For this, the studied samples were welded applying a range of axial forces. The welded joints were characterized by, α/γ phase ratio, intermetallic quantification, austenite spacing measurement, microhardness profile and microstructural qualitative studies. The results showed the efficiency in repair of the FHPP process on the production of DSS joints according with the material recommendations from the standard DNV-RP-F112.

Friction Stir Welding (FSW) is an excellent alternative for joining dissimilar and similar materials in comparison to conventional welding processes. In this sense, this work aims at qualifying FSW to similar AA5083-O and AA5052-O aluminum alloys, with 6.35 mm thickness, in a CNC machining center. Therefore, four welding experiments were undertaken. At first, two types of plate surface finish were considered before joining. Afterward, two tool probe geometries, and changes in the base material position were evaluated. Hence, the welds were mainly analyzed by metallography, tensile testing, and bending tests. Results showed that the machining step to oxides removal and plates alignment is beneficial for the weld processing and the factor that has significant influence to achieve suitable joints is the tool probe geometry. Finally, by obtaining an average ultimate tensile strength (UTS) of around 191 MPa, enhanced microhardness, and bent angle of approximately 150°, the best joint was chosen.

This work presents friction hydro-pillar processing (FHPP) and tungsten inert gas (TIG) welding of SAF2205 duplex stainless steel. Weld microstructural and mechanical characterisation were carried out based on the standards (DNV-RP-F112 and DNV-OS-F101). Therefore, optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction were used. In addition, mechanical properties were evaluated by microhardness measurements. Furthermore, the joining processes were thermodynamically simulated for confirmation of the expected phases in each welding method. It was possible to verify the phases developed after the experimental welding (FHPP and TIG) as well as the ones obtained in the thermodynamic analyses. Finally, it was noted that FHPP promoted mechanical and metallurgical features requested by the standards.

In order to protect industrial components, cobalt base alloys are applied as hardfacing material through welding techniques. A large number of papers have shown that controlling the chemical composition is a key point regarding the wear and corrosion resistance of coatings. This paper investigated the effect of bead overlapping on the microstructure and properties of CoCrWC alloy coatings. Mechanical properties were determined by hardness, sliding wear and microtensile tests. Bead overlapping reduces dilution during the previous bead melting, which in turn induces lower iron content. From the second bead on, an increase in the amount of interdendritic carbides and solid solution alloying was verified, accounting for the higher mechanical properties of the coatings.

No abstract

Friction welding is a solid state technology which has been used worldwide. Potential advantages may be recognized as reducing welding project costs, weld weight, environmental impact and to promote enhanced mechanical properties. However, traditional welding methods are still a common practice in many engineering areas. In this sense, this work aims to present the technical advantages for replacing gas metal arc welding (GMAW) by friction welding for joining hydraulic cylinder tubes. The feasibility of friction welding was demonstrated by microstructural analysis, mechanical properties and hydrostatic pressure testing. The results showed enhanced mechanical properties for the friction welded tubes. In addition, macro and microstructural features presented distinguishable process characteristics which reflect in different microhardness values. The friction weld exhibited a better behavior in bending as well as hydrostatic tests.