Two artificial neural networks (ANNs) were developed for producing an austempered ductile iron (ADI) with low-cost chemical composition and mechanical properties as per ASTMA897/897M-16-grade-1050/750/07 standard. Thus, the first ANN predicted the chemical composition range within the lowest cost and required mechanical properties. Next, in the second ANN, the resulting values from the first ANN were refined considering the target chemical composition suggested in the standard. Moreover, mechanical properties and microstructural analyses were undertaken in the ADI produced to support the ANNs’ findings. Hence, ANNs can be used to make a standard-compliant ADI and achieve cost savings.

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.

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.

A soldagem por arco elétrico é a técnica mais empregada para reparar estruturas de grande porte, mas apresenta desvantagens associadas à solidificação do metal de solda. Então a utilização de processos de solda por atrito, especificamente o processo FHPP (Friction Hydro Pillar Processing) que consiste na utilização de pinos para reparo por atrito, apresenta vantagens por ser um processo realizado no estado sólido. Menores temperaturas estão envolvidas e não existe influência do ambiente externo, minimizando os problemas nos reparos estruturais. Este trabalho teve como objetivo observar a variação dos parâmetros do processo e os efeitos desses na microestrutura e qualidade do reparo. O estudo comparou diferentes forças axiais nos reparos com aço C-Mn através de metalografias e perfis de microdureza. Uma força axial maior resultou em um menor tempo de processo, em uma microestrutura mais homogênea e evitou os defeitos "falta de adesão" na zona de ligação e "cisalhamento a quente" do pino.

The arc welding it is the most used technique to repair large structures, however, has disadvantages that result from the solidification of the weld metal. So the use of friction welding, specifically the FHPP (friction hydro pillar processing) process that consists on using plugs for friction repair, presents advantages because it is a process that is carried out on the solid state. Lower temperatures are involved and do not have the influence of the external environment, minimizing the problems on structure repairs. This work has the objective of observe the process parameters variation and their effects on microstructure and on the quality of the repair. The study compared different axial forces on repairs whit C-Mn steel through of metallographic and microhardness profiles. A higher axial force results in less time of process, in a more homogeneous microstructure, and avoided the defects "noncompliance" in the bounding zone and "hot shear" of the plug.