Chapter 10 Assessing Bond Strength in 304L Stainless Steel Plate Welded Using Plastic Explosives Thomas A. Ivanoff, Olivia D. Underwood, Jonathan D. Madison, Lisa A. Deibler, and Jeffrey M. Rodelas Abstract Explosive bonding is a dynamic joining method used to rapidly create metallurgical bonds between two metals. These interfaces can exhibit strengths greater than the parent materials and contain little porosity. Bond quality, however, is highly dependent on processing parameters. Explosive bonds fueled by ammonium nitrate have been extensively characterized, but processing windows for plastic explosives have not. Here, bond strength in 304L stainless steel plate explosively bonded using rubberized/plastic explosives are assessed using shear by tension loading of single-lap-joint specimens. The effects of collision velocity and collision angle on bond quality and strength are investigated and used to define a processing window. Failure modes varied across both the process space studied and within individual bonds. Microstructural analysis across fractured interfaces is combined with fractography to describe the different failure modes and variable strength across bond interfaces. Keywords Welding · Bond strength · Fractography · 3D characterization · Tension 10.1 Introduction Explosive bonding is an unconventional metal joining process that utilizes a shock wave to propel a moving object (flyer material) into a fixed object (target material) at sufficient velocity to form a metallurgical bond between the flyer and target materials. A variety of methods can be employed to provide the required shock loading, but detonating explosives are one of the most common [1, 2]. Explosive bonding, or welding, has several advantages over traditional joining methods, such as arc welding or soldering/brazing. First, explosive welding can be used to rapidly form metallurgical bonds between similar and dissimilar metals across large surface areas [3, 4]. Explosive welding is used commercially in large plate and pipe cladding operations [1–3]. The bonds that are formed can be and often are stronger than either base material [5]. Explosive welding, when properly conducted, is a solid-state bonding process. This alleviates the formation of defects such as oxides, remelting products, and shrinkage pores often associated with liquid welding processes. Explosive welding presents challenges beyond the obvious safety requirements for handling explosives. A main challenge is in reducing nonuniform bonding and ensuring uniform bonds formed across large surface areas do not display varying strengths or levels of porosity. Additional challenges include regions of localized melting and plastic damage to the workpiece. Though these challenges are ever present, proper experimental setup can be used to mitigate most if not all of the challenges associated with explosive bonding. 10.2 Background In this study, explosive bonding was used as the closure mechanism for a stainless steel gas flow valve in the Z machine at Sandia National Laboratories. Explosive bonding was used because it provided a reliable and fast method of creating a hermetically sealed bond. Hermeticity was necessary to ensure no hazardous compounds escaped from the test environment through the pipe. To evaluate the proper welding conditions for this valve, bonding experiments were completed using plates T. A. Ivanoff ( ) · O. D. Underwood · J. D. Madison · L. A. Deibler · J. M. Rodelas Sandia National Laboratories, Albuquerque, NM, USA e-mail: tivanof@sandia.gov; odunder@sandia.gov; jdmadis@sandia.gov; ldeible@sandia.gov; jmrodel@sandia.gov © The Society for Experimental Mechanics, Inc. 2021 S. Xia et al. (eds.), Fracture, Fatigue, Failure and Damage Evolution, Volume 3, Conference Proceedings of the Society for Experimental Mechanics Series, https://doi.org/10.1007/978-3-030-60959-7_10 65
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