Microstructure Of AISI Research Articles

Evolution of microstructure of AISI 347 stainless steel during heat treatment

AbstractThe microstructural changes caused by various thermomechanical treatments were investigated for AISI 347 stainless steel. The high dislocation density which results from cold rolling is not annealed out even after long holding times at 600°C. When heating at higher temperatures, e.g. 750°C, precipitation of very fine NbC particles is observed, together with onset of recrystallisation. Complete recrystallisation resulting in equiaxed dislocation free grains occurs only when annealing severely cold worked specimens in the high temperature range of this investigation.MST/1708

Helium effects on the post-implantation creep properties and the microstructure of AISI 316L welds and parent material

Abstract The influence of implanted helium on the creep properties in electron-beam welds of the Next European Torus (NET) reference material, AISI 316L, and its parent material in the as-received condition has been investigated at 873 K. Helium degredation effects (i.e. reduced creep rupture time and creep rupture strain) are more serious in the parent material than in the welds. The fracture mode for implanted weld specimens is usually transgranular, while for the parent material specimens it is mixed trans- and intergranular. TEM investigations show that in the welds there is a lot of σ-ferrite at grain boundaries (occupying about 50% of grain boundary area) and in the interior of grains as well. Helium bubble sizes increase with increasing helium concentration, while helium bubble densities remain constant. Helium bubbles in the matrix are larger in size but much lower in density than those at boundaries or interfaces.

Microstructure of Deformed AISI 4340 Steel

The microstructure of low alloy steels has been studied by several investigators. They have shown that when low alloy steel is quenched from 1200°C, the martensite formed exhibits packets of dislocated laths containing auto tempered carbide within the laths and thin films of retained austenite at the lath boundaries. The present study is aimed to investigate the effects of deformation on microstructure of AISI 4340 steel. Tensile plate specimens were austenitized at 1200°C for 1 hr in argon atmosphere, oil quenched and tempered at 180°C for 1 hr. Following the heat treatment, these specimens were uniaxially pulled in tension and thin foils for TEM were taken from the surface of broken tensile specimen. Foils were also prepared from undeformed region. These foils were observed at 100 kv in Hitachi HU 11B microscope.

High Cycle Rolling Contact Load Effects on the Microstructure of 50 Rockwell C AISI 52100 Steel

An experimental program to determine the effect of cyclic radial rolling contact load on the microstructure of AISI 52100 steel quenched and tempered to 50 Rockwell C hardness is reported. The magnitude of the load was restricted to result in stress conditions that did not exceed the strain energy of distortion theory limit of elastic behavior. Cycling up to 109 cycles produced familiar “white etching” microstructural alterations around stress concentrators such as inclusions, but no microstructural effect related to the mathematical stress field was detected. Research to improve the elastic limit in high hardness-wear resistant steel appears to be needed.