Of interest with steel block planes is the patent received by Edmund Schade in 1915 – No. 1, 164,615. This patent for a “stamped steel plane” was the basis of Stanley’s stamped steel planes, the S4, S5, and S18, produced from 1925/26 to 1942.
In Australia, inventor Robert McConnell patented a pressed steel plane in 1942 (Aust. Patent No. 116098). A brief explanation with pictures of one of the planes is shown in this section from a book titled “Australian Woodworking Planemakers”, by Trevor Semmens.
There were of course other pressed-steel block planes, usually of a lower quality. The TWIX company of New York state made a pressed-steel block plane. I have not been able to secure a nice looking version of this plane, most it seems are in pretty ratty condition.
There was also a series of planes made by French manufacturer Goldenberg.