Abstract
The cobalt alloys "Stellite No.6 and No.21 " are welding materials and have excellent properties to resist corrosion, wear and erosion. On this account these alloys are applied to the valves and many other machinery parts. However, these alloys show unexpected erosion damages under a certain kind of fluid conditions. The preceding study clarified that the good erosion properties of these alloys may be attributed to the features of the t phase transformations. On the contrary, these alloys show greater erosion damages comparing with other alloys under the slight or no E phase transformed fluid conditions. The iron contents of these alloys are increased by the improper welding conditions. This study is carried out to clarify the effects of the iron contents to the cobalt base alloys erosion properties by the room and hot water jet impact tests. Test results suggest that the quantity of iron to prevent the formation of ε phase accelerate the erosion of these alloys.
