US 2061370 A
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Patented Nov. 1 7, 1 936 UNITED STATES PATENT omca 2,061,310 I near nasrsrma ARTICLE Wilhelm Rohn, Hanau-on-the-Main, Germany No Drawing. Application January '1, 1935, Serial No. 735. In Germany January 18, 1934 Z-Claims. (Cl. 75 -124) 0 which hitherto were generally used for heating elements however their workability with aluminum contents exceeding 6% is unsatisfactory. It has been attempted to diminish the grain size and thereby to improve the workabilityofl these alloys by adding thereto certain elements such as titanium, zirconium or cobalt. However all these additions do not improve the heatfresijst ing qualities of the alloys because they det M 7 rate the dense mixture of aluminum and. chro' v um oxide firmly adhering to the surfaces of heating elements and produce pulverulent and brittle oxides. V
Numerous experiments of. the inventor have shown that for the production of elements for which a high resistivity to heat is required, even after they are worked and have been exposed to elevated temperatures for a long while, alloys aresuitable containing besides iron aluminum 0.1 to 11.5%, chromium 0 to 30% and a metal or metals or the rare earths, especially cerium 0.05
to 2%. The metals of the rare earths favorably influence the durability and the life of the alumle num-iron or chromium-aluminum-iron alloys which in themselves are already highly resistive to heat. durability, i. e. the time required until burning out at 1200 C. of an alloy consisting of chromium a 30%, aluminum 5%, remainder iron, could be trebled by the addition of 0.2% cerium.
The cerium may preferably be added in the 0 form of the so-called cerium mixed metal containing, besides cerium, other metals of rare earths invarious proportions, for instance, lanthanum, dysprosium.
The quantity of the rare earth metals preferl5 ably amounts to 0.05 to 2%. I
The rare earth metals are preferably added ashort time before casting-in order to reduce as (are: p ssible the waste of these metals. The rarev earth metals may be introduced into-the 20 or into the casting-jet.
1.-.-Heat resisting articles 1n wrought condition containing aluminum 0.1 to 11.5%, chromium up to 3d% and metals of the rare earths 0.05 to 2%,
the remainder being substantially iron.
2. Heat resisting articles in wrought condition containing aluminum 0.1 to11.5%, chromium up to and cerium 0.05 to 2%, the remainder being-substantially iron.
v WILHELM ROI-IN.
For instance, it was found that the 5