HELIUM ENVIRONMENTS

PROFESSOR P. HANCOCK

Cranfield Institute of Technology

I have been asked to give some general comments on the effect of environment on mechanical properties. It seems that in the particular helium environments, in which this Conference, is interested, that slight traces of hydrogen, carbon monoxide, water vapour and methane are likely to be the main contaminants. Under these conditions internal oxidation, or even carburisation, of many of the alloys used is likely to take place. If this happens the discontinuities which will be formed within the material will undoubtedly effect the mechanical properties of the underlying material and in paper 18 Dr. Wood and his co-authors have showed the marked effect that internal oxidation has on reducing the creep properties of Incaloy 800 and 316 stainless steel.