EFFECT OF BORIDE ON STRESS RUPTURE PROPERTIES OF AN FeNiCr-BASE ALLOY

The effect of boron on the high temperature strength of an Fe-42Ni-12Cr-4W-1. 5Mo-4.5Ti-2Al alloy has been investigated. The results indicate that the boron either soluted in solid solution or precipitated as a secondary boride phase along the grain boundaries will improve the stress rupture properties of the alloy. But the primary borides can not better it at all, moreover, it may deteriorate the high temperature strength of alloy if an overabandant primary boride occurred. It was also found that the stress rupture properties of alloy have much improved since it solution treated under elevated temperature, this seems to attribute the improvement to the increase of the amount of secondary boride precipitation at unit interface area after solutioning and aging, not to the grain growth alone from higher solution temperatures in the tested range of grain size.