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Dissimilar welding of Inconel 713LC superalloy and high strength AISI 4140 steel was conducted using Electron Beam (EB) welding process. The present research study focuses on the effect of post-weld heat treatment (PWHT) on the produced dissimilar joints' microstructure, mechanical properties and corrosion behavior assessment. PWHT was accomplished at 650°C for 2, 4 and 6 h, following air cooling. The microstructure study was carried out by light optical (LOM) and scanning electron microscopy (SEM), coupled with energy-dispersive spectroscopy (EDS) analysis. The mechanical behavior of the EB joints was investigated via Vickers hardness testing. For the assessment of the EB joints' corrosion resistance, potentiodynamic polarization tests were performed in 3.5 wt.% NaCl solution, at various temperatures. The corrosion products evaluation was carried out by both x-ray Diffraction (XRD) and scanning electron microscopy (SEM). PWHT leds to the microstructure modification of both Inconel 713LC and AISI 4140 in the dissimilar welding zones. The heat treatment holding time increment resulted in the development of more uniform mechanical response among base metals and fusion/heat affected zones, whereas corrosion resistance became progressively weaker. [ABSTRACT FROM AUTHOR]

Case study inverse thermal analyses of A12139 and Al2198 electron beam welds are presented. These analyses represent a continuation of previous studies using laser beam welds, but provide accessibility to different regions of the parameter space for temperature histories than achievable using laser beams. For these analyses, a numerical methodology is employed, which is in terms of analytic functions for inverse thermal analysis of steady-state energy deposition in plate structures. The results of the case studies presented provide parametric representations of weld temperature histories, which can be adopted as input data to various types of computational procedures, such as those for prediction of solid-state phase transformations and their associated software implementations. In addition, these weld temperature histories can be used for construction of numerical basis functions that can be adopted for inverse analysis of welds corresponding to other process parameters or welding processes process conditions of which are within similar regimes. [ABSTRACT FROM AUTHOR]

The aim of present investigation is to study the effect of an electron beam surface treatment on 2205 duplex stainless steel joints produced by the same electron beam process. Heat treatment of the joints is necessary, to re-establish the ferrite/austenite balance, which is extremely disturbed during the electron beam welding process. For assessing the effectiveness of the electron beam surface treatment, similar weld joints were subjected to conventional furnace heat treatment at 1050 °C, and used as reference. Metallographic techniques and mechanical testing were used to assess the microstructure and corresponding mechanical properties of the as-welded and heat treated specimens. The metallographic results showed that an austenite/ferrite ratio approaching the one produced by a typical furnace post-weld heat treatment can also be achieved by heating locally the weld surface with an electron beam. At the same time the tensile properties show considerable improvement, approaching those obtained by means of a conventional furnace heat treatment, whereas the impact strength is also improved compared to the as welded specimen, but remains clearly lower than the one of the furnace heat treated weld. [ABSTRACT FROM AUTHOR]