[3][4] Their experiments were characterised by a scientific empiricism in that many different combinations were made and tested, with no regard for conventional wisdom, and detailed records kept of each batch.
The result was a heat treatment process that transformed existing alloys into a new kind of steel that could retain its hardness at higher temperatures, allowing cutting speed to be tripled from 30 surface feet per minute to 90.
Heavier machine tools with higher rigidity were needed to use the new steel to its full advantage, prompting redesigns and replacement of installed plant machinery.
[2] Although molybdenum-rich high-speed steels such as AISI M1 had seen some use since the 1930s, it was the material shortages and high costs caused by WWII that spurred development of less expensive alloys substituting molybdenum for tungsten.
Combining molybdenum, tungsten and chromium steel creates several alloys commonly called "HSS", with a hardness of 63 to 65 Rockwell C. The addition of cobalt increases heat resistance, and can give a hardness up to 70 Rockwell C.[14] HSS drill bits formed by rolling are denoted HSS-R. Grinding is used to create HSS-G, cobalt and carbide drill bits.
[16] The main use of high-speed steels continues to be in the manufacture of various cutting tools: drills, taps, milling cutters, tool bits, hobbing (gear) cutters, saw blades, planer and jointer blades, router bits, etc., although usage for punches and dies is increasing.