Charles H. Cadden

Hydrogen-assisted fracture of inertia welds in 21Cr-6Ni-9Mn stainless steel

Publisher Summary This chapter intends to quantify the fracture resistance of inertia welds in 21Cr-6Ni-9Mn stainless steel, emphasizing the effects of dissolved hydrogen. Fracture mechanics methods are effective in measuring the initiation toughness and crack growth resistance curves of hydrogen-charged and uncharged inertia welds. Hydrogen degrades the fracture resistance of inertia welds, although assessing the degree of embrittlement is hindered by nonuniform microstructures and defects in the bond regions. The fracture toughness of uncharged inertia welds is lower than the associated uncharged base metal. While the fracture modes are consistently microvoid coalescence, the voids that nucleated in inertia welds are more closely spaced leading to void coalescence at relatively smaller strains and lower fracture resistance. The fracture resistance of inertia welds is lower than the associated base metal for both the uncharged and hydrogen-charged conditions. The dimples on inertia weld fracture surfaces are smaller than those on the base metal fracture surfaces. Small dimples typically result from closely spaced voids that grow limited amounts prior to coalescence. This process requires relatively small amounts of plastic strain, which leads to lower fracture resistance.

Ceramic-Metal Brazing, From Fundamentals to Applications: A Review of Sandia National Laboratories Brazing Capabilities, Needs and Opportunities

The purpose of the report is to summarize discussions from a Ceramic/Metal Brazing: From Fundamentals to Applications Workshop that was held at Sandia National Laboratories in Albuquerque, NM on April 4, 2001. Brazing experts and users who bridge common areas of research, design, and manufacturing participated in the exercise. External perspectives on the general state of the science and technology for ceramics and metal brazing were given. Other discussions highlighted and critiqued Sandias brazing research and engineering programs, including the latest advances in braze modeling and materials characterization. The workshop concluded with a facilitated dialogue that identified critical brazing research needs and opportunities.