"The K-Metal from Krypton" was completed in late 1940 and would likely have been published that same year with a coverdate of early 1941. This would have placed it directly after the events of Action Comics #31 and Superman #7.
These stories leading into the events of "The K-Metal from Krypton" are available in The Superman Chronicles, which reprints, in color, every Superman story in chronological order:
Superman Chronicles Volume One|
Reprints Action Comics #1 through #12, New York World's Fair #1, Action Comics #13, and Superman #1; all originally published in 1938 and 1939. By Jerry Siegel and Joe Shuster.
Superman Chronicles Volume Two|
Tales from Action Comics #14 through #20 and Superman #2 and #3, from 1939 and 1940. As with Volume One, all stories are by Superman co-creators Jerry Siegel and Joe Shuster.
||Superman Chronicles Volume Three|
Continues reprinting Superman's adventures in chronological order from where Volume Two left off in 1940.
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