耐熱合金の燃焼灰腐食抵抗と腐食環境でのクリープ破断特性におよぼすAl被覆の効果

抄録

The protective effect on fuel oil ash corrosion of hot dipped aluminum coating was compared with that of calorizing for typical austenitic stainless steels by means of a furnace test method authorized by the Committee on Heat Resisting Metals and Alloys of JSPS in which specimens pre-coated with synthetic ash composed of 85%V₂O₅ plus 15%Na₂SO₄ were heated in air. The resistance to fuel oil ash corrosion for many kinds of typical heat resisting alloys before and a fte hot dipping was evaluated by the same test method. It was revealed that owing to higher aluminum concentration of surface layer hot dipping had very excellent protective effect on corrosion of these alloys.
When the synthetic ash was pre-coated to specimens, remarkable decrease in creep rupture strength of SUS 316 steels resulting from an increase in minimum creep rate due to corrosion was observed. Hot dipping, however, raised the creep rupture strength of specimens pre-coated with ash to the same level as that of specimens without hot dipping and pre-coating of ash as a result of a decreas of creep rate due to prevention of corrosion. The effect of calorizing was less than that of hot dipping and the strength of steels was reduced in some degree in calorizing process followed by furnace cooling.