抄録
The effects of molybdenum and heat treatments on the creep properties and micro-structures of 0.15C-15Cr-14Ni heat resisting steels have been studied. The relationships between creep properties and several structural factors and discussed. The results are as follows:
The creep rupture strength and creep strength increase with the molybdenum content. Below 1% molybdenum, the creep rupture strength decreases with increasing solution temperature, but over this content it has a maximum at the solution temperature of 1 150°C. It is found that the increment of the creep rupture strength due to molybdenum addition is proportional to the product of { (%C) sol} 0.5× { (%Mo) sol} 0.5× (nI) 0.5× (Dr) 0.5, where (%C) sol and (%Mo) sol are the contents of carbon and molybdenum in austenite matrix, respectively; nI is the distribution density of undissolved carbides and Dr is the mean austenite grain diameter after solution treatment. This is explained by the combination of the following factors; the solid-solution hardening by carbon and molybdenum, the dispersion strengthening by undissolved and precipitated carbides, and the effect of the grain size. Massive, cubic and ribbon-like M23C6 and rod-like M6C were observed in the creep ruptured specimens of these steels.
