Dislocation substructures in high-energy-rate-forged and press-formed 21-6-9 stainless steel

Abstract

A Transmission Electron Microscope (TEM) was used to establigh that the substructure of Press Formed (PF) 2 1-6-9 stainless steel toroids was characterized by a dislocation cell size finer, about 0.16 pm, than that of about 0.29 pm, of High-Energy-Rate-Formed (HERF) processed toroids. In addition, HERF processed material showed areas of a coarser, well-developed subgrain structure characteristic of hot work deformation. The formation of the substructures, as-well-as the grain size and carbide distributions of the toroids produced by the two processing techniques, are discussed in terms of the various operations, temperatures, and strain rates associated with the two different processing schedules. The Press-Formed toroid had a higher yield strength than the HERF processed toroid which was attributed to the finer cell size of the PF processed toroid.

Tritium Aging Effects on the Fracture Toughness Properties of Forged Stainless Steel

“…In fact, this study showed that sensitization heat treatments at 650°C would lower the fracture toughness values of conventional forgings just as it did for high-energy rate forgings (Figure 8). That fact that sensitization occurs in high-energy-rate forgings has been pointed out in earlier studies (12)(13)(14) and it may appear occasionally in reservoir microstructures. Furthermore, since cold work and nitrogen increase the kinetics of sensitization in Types 304L and 304LN stainless steels (15)(16), these factors will increase the potential for sensitization in Type 21-6-9 stainless steel, too.…”

Solidification behaviour of laser welded type 21Cr–6Ni–9Mn stainless steel

“…The calculated phase diagram shows the solidus is at approximately 1380°C, close to the 1355°C reported in the literature. 29 The increased nitrogen level of Heat 2 moves the solidification path closer to the region of primary austenite solidification. Less undercooling would be required for Heat 2 to shift solidification mode from primary ferrite to primary austenite relative to Heat 1, agreeing with the shift in solidification mode observed in the welds.…”

Flow Behavior of 430 Ferritic Stainless Steel at Elevated Temperatures

“…High strength-to-weight ratios in austenitic stainless steels for aerospace applications are typically achieved by relatively low final hot working temperatures in order to retain the dense dislocation substructure [4][5][6]. Recently, ferritic stainless steels have been developed to substitute austenitic stainless steels in some applications, as automotive exhaust components, specially the upstream part of the exhaust line (manifold, down-pipe, converter shell), where temperatures can reach 1100°C.…”