Precipitation reactions in a beryllium-bearing stainless steel

Precipitation reactions in a beryllium-bearing stainless steel alloy have been studied by TEM and electron diffraction for ageing temperatures between 400/sup 0/ and 900/sup 0/C. The nominal composition of the alloy was 38% Ni - 21% Cr - 1% Mn - 0.5% Be - Bal Fe. Specimens were solutionized for one hour at 1150/sup 0/C and water quenched. The ageing reaction was studied by hardness measurements for times between 0.5 and 16 hours. The TEM specimens dicussed herein were made from samples aged one hour

Modeling of the Effects of Surface-Active Elements on Flow Patterns and Weld Penetration

A mathematical model was developed to calculate the transient temperature and velocity distributions in a stationary gas tungsten arc (GTA) weld pool of 304 stainless steels with different sulfur concentrations. A parametric study showed that, depending upon the sulfur concentration, one, two, or three vortexes may be found in the weld pool. These vortexes are caused by the interaction between the electromagnetic force and surface tension, which is a function of temperature and sulfur concentration, and have a significant effect on weld penetration. For given welding conditions, a minimum threshold sulfur concentration is required to create a single, clockwise vortex for deep penetration. When two metals with different sulfur concentrations are welded together, the weld-pool shape is skewed toward the metal with a lower sulfur content. Detailed physical insights on complicated fluid-flow phenomena and the resulting weld-pool penetration were obtained, based on the surface tension-temperature-sulfur concentration relationships