Yoni Adonyi

1 WELDABILITY OF HIGH PERFORMANCE STEELS Yoni Adonyi1 Abstract ... The diffusible hydrogen was measured on-site using the mercury method specified in the American Welding Society AWS A 4.3-93 specification. The typical setup for testing is shown in Figure 1a. ...

Microwave joining is a relatively new process that holds great potential for joining dissimilar materials such as ceramics and metals. Internal heat generation in the material, prevention of thermal shock to the ceramic, reduced interlayer diffusion, and a smaller mismatch in thermal expansion between the base materials are significant advantages of microwave heating over conventional heat sources for joining ceramics to metals. Yet, the challenge of coupling the microwave to the target has prevented significant application of this joining process in industry. This paper demonstrates how numerical modeling was used to improve coupling of the microwave to the target and allow incorporation of a pressure fixture needed to increase joint strength. Numerical modeling insights were incorporated into a joining model that predicted a process time and final temperature that would cause melting of the interlayer. The experimental prototype was used to solder copper to thermoelectric materials using a ferrite susceptor to absorb microwave losses and transfer heat to the joint and melt the interlayer. The final temperature of the interlayer was within 5% error of the prediction by simulation. This validated joining model improved the existing method for microwave joining of a ceramic to a metal by increasing joint strength.

Four different solid-state welding processes are compared with fusion welding in HPS steels and a new structural ferritic stainless steel, the A 1010.  Gleeble simulations were used to contrast the effect of heat input on the HAZ properties and the high-frequency welds resulted in the best toughness.  This was presented at CANMET in Vancouver, Canada in September 2014 and came out in their proceedings.

Making the point that Education is a misused word by some professional organizations and companies to describe Training. 
Believe it or not, but one person was actually inspired by it and chose to pursue a career via Welding Engineering Education - directed him to Steve Liu at Colorado School of Mines

Pre- and post heating in friction stir welding is not a new concept.  However, high frequency induction heating was used to offset the difference in thermal conductivity of the two base metals (in addition to the pin offset).  It was fond that changing the volume fraction of aluminum rich copper intermetallics made the weld more ductile.

The geometry and orientation of this High Frequency Resistance Weld centerline feature should be used as a seam weld quality predictor instead of being treated as a flaw. ABSTRACT High Frequency Resistance Welding (HFRW), a.k.a. Electric Resistance Welding (ERW), is a high-speed, solid-state welding process mainly used for making longitudinal seams in tubular products. This automated process produces thousands of miles of good welds yearly, yet because of its high reliability it is seldom mentioned in the technical literature. However, recent ERW welding difficulties of new high strength steels brought more visibility to this process. Our paper discusses the characteristics of the centerline metallographic feature known as the bondline in several carbon-and stainless-steel grades, because some ERW flaws typically occur along the same location. Based on the examination of a multitude of weld cross sections and physical simulations, it was found that bondlines are the results of insufficiently squeezed-out high temperature products and can indeed be related to flaw formation elsewhere in the weld. The microstructure and properties of these bondlines vary depending on the steel composition: mainly soft delta ferrite in low alloy steels or a mix of bainite and hard martensite in alloy steel grades. We have also found that it is not the relative hardness or width of these bondlines are relevant. Instead, their geometry, orientation and uniformity are effective in predicting the weld quality along the longitudinal seam. Therefore, this paper should be useful for tubular structure designers, ERW mill operators and welding engineers still unfamiliar with the HFRW/ERW process. 2