ROLE OF TUNGSTEN FOR THE MECHANICAL-PROPERTIES OF HIGH-PURITY FE-50 MASS-PERCENT CR ALLOYS AT ELEVATED-TEMPERATURES

The effect of tungsten on the mechanical properties and the microstruc ture of high-purity Fe-50 mass% Cr alloys was investigated by tensile tests and by optical microscopy in the temperature range between 873 a nd 1073 K. The yield stress increased by the addition of W at temperat ures above 873 K, especially above 973 K, due to the solid-solution ha rdening mechanism. A W-free alloy tested above 873 It failed by interg ranular fracture and the reduction of area was below 60%. On the other hand, an alloy doped with 8 mass% W showed transgranular fracture abo ve 873 K and the reduction of area was more than 70%. The addition of W suppressed the nucleation of cavities at grain boundaries.