This chapter describes the characteristic damage of a mid-air explosion and how it appears in metal debris recovered from crash sites of downed aircraft. It explains that explosive forces produce telltale signs such as petaling, curling, spalling, spikes, reverse slant fractures, and metal deposits. Explosive forces can also cause ductile metals such as aluminum to disintegrate into tiny pieces and are associated with chemicals that leave residues along with numerous craters on metal surfaces. The chapter provides examples of the different types of damage as revealed in the investigation of two in-flight bombings.

This chapter discusses some of the ways that the lessons learned from failures have benefitted society, leading to improved product designs, better materials, safer industrial processes, and more robust codes and standards. It also provides several examples of how the technology and procedures associated with aviation security have been upgraded in the wake of air disasters.

Solid-state welding processes are those that produce coalescence of the faying surfaces at temperatures below the melting point of the base metals being joined without the addition of brazing or solder filler metal. This chapter discusses solid-state welding processes such as diffusion welding, forge welding, roll welding, coextrusion welding, cold welding, friction welding, friction stir welding, explosion welding, and ultrasonic welding.

Many factors must be considered when welding dissimilar metals, and adequate procedures for the various metals and sizes of interest for a specific application must be developed and qualified. Most combinations of dissimilar metals can be joined by solid-state welding (diffusion welding, explosion welding, friction welding, or ultrasonic welding), brazing, or soldering where alloying between the metals is normally insignificant. This chapter describes the factors influencing joint integrity and discusses the corrosion behavior of dissimilar metal weldments.