Hi Martin,
They look like "cutters", "Irons", or "knives", as used in woodworking machinery such as multi head moulders, spindle moulders and tenoning machines. The HSS is usually just a thin piece laminated to mild steel or similar, as seen in your picture of the edge of the cutter.
The cutters are held on a Tee slotted Square Block by a single bolt. The "open slot" type were frowned upon or possibly banned before the "closed slot "type, as they could more easily fly out of the machine!!! All this type were banned around 1998 if memory serves.
Think of a couple of axe heads spinning at 6000 RPM!!!
Couple of pictures from a Wadkin catalogue circa 1954.
![img_20220522_125540534_hdr.jpg img_20220522_125540534_hdr.jpg](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)
![img_20220522_125917483.jpg img_20220522_125917483.jpg](data:image/gif;base64,R0lGODlhAQABAAAAACH5BAEKAAEALAAAAAABAAEAAAICTAEAOw==)