Short-term thermal response of rapidly solidified Type 304 stainless steel containing helium.

摘要

Type 304 stainless steel was heat treated for short times near its melting point in order to determine its microstructural response to thermal cycles typical of the near heat-affected zones of welding processes. The material was rapidly solidified as a powder by centrifugal atomization in a helium environment and consolidated by hot extrusion. Along with the ingot metallurgy material used for canning the powder prior to hot extrusion, it was heat treated using a Gleeble at temperatures of 1200 and 1300(degree)C for times ranging from <1 to 1000 s, and the samples were examined for microstructure and the existence of porosity due to entrapped helium. At higher test temperatures and longer treatment times, the material developed extensive porosity, which was stabilized by the presence of helium and which may also have a role in anchoring grain boundaries and inhibiting grain growth. The powder material. At lower test temperatures and shorter treatment times, grain growth in the (gamma) phase appeared to be restricted in the powder material, possible by the presence of helium. An intermediate temperatures and times, a (gamma)-(delta) duplex microstructure also restricted grain growth again occurred in the (delta) microstructure. 9 refs., 14 figs., 3 tabs.