Corrosion resistance behavior of FeCrAl resistance heating alloy
In order to improve the corrosion resistance of Iron-aluminum alloy, another alloy constituent is added, that doesn't ruin or change the oxidation resistance properties of alloy. Chromium due to its fixed ability to improve the corrosion resistance of other alloys is the best option. The Fe-Cr-Al resistance heating alloys are vacuum melted. The heat chosen for the additional oxidation analysis consisted of 8% aluminum with 2.50, 4.75, 7.25 and 9.50 constitution% chromium.It was found that more useful information can be obtained if the test temperature is kept between 1800oF to 2200oF for 100 to 500 hours time span. Color plate 2 shows the comparison of oxidation resistance offered by FeCrAl resistance heating alloy and Fe-Al alloys.
No ruining oxidation was found in any material after 500 hours at temperature 1800oF. Those materials kept at 2200oF for 100 hours are comparatively unaffected. After 100 hours at 2200oF the 2.50% of FeCrAl alloy was severely scaled and 4.75% chromium was also scaled however not as much. The sole material that kept unaffected for 500 hours at 2000 to 2200oF was FeCrAl containing 7.25% chromium. The remaining testing materials were seriously affected that blistering, desquamation and end cracking occurred.
As 7.25% iron- chromium-aluminum alloy wire was unaffected while 9.50% chromium alloy completely damaged, it was considered that the latter was corroded uniformly. Although the repeated analysis were performed that described that high content of chromium and aluminum content have ruining effect on the oxidation resistance of iron-aluminum alloy at temperature more than 2000oF> Why this is not clear at chromium content of 7.25% is not known at this time.
The anomalous effect of chromium concentration more than 7.50% will be more analyzed. The current planning calls for an analysis of the effects on oxidation resistance of larger carbon content in 9.50% of FeCrAl alloy.
Another heat consisting of aluminum 7.50% and 7.50% chromium was created. On oxidation at 2200of for 500 hours the material from this heat also attained superior oxidation resistance. Thin white oxide film was produced that on quenching was eradicated to show a bright surface just like that was observed on 12 to 16% Iron – aluminum alloy. The additional content of 0.32% silicon seemed to decrease the oxide layer thickness nominally. In this analysis of corrosion and oxidation resistance of Iron-chromium-aluminum alloy, the room temperature tensile analysis were conducted to find the ductility of these alloy. The information obtained from this analysis is showed in the following table.
Low density, High specific strength, Excellent corrosive resistance, Rustless,
Good thermal stability, Good thermal conductivity, Biological features, Plasticity, etc.
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