Just a wild guess but searching the net this morning I ran across 4140HT steel that seems to have been in use in the twenties, perhaps earlier in Ford axles. It comes in a hardened state but can easily be annealed. High tensile strength and corrosion resistant. Hence the possibility of the HT over A stamp to designate the type of steel. This would go along with what Dave suggested above. If it does turn out to be a stamp for 4140HT steel it places Parker at the leading edge of metal technology in the 1920's.
More trivia information is here:
http://www.ehow.com/info_8313491_pro...-ht-steel.html
Quote from Wikipedia:
"41xx steel is a family of SAE steel grades, as specified by the Society of Automotive Engineers (SAE). Alloying elements include chromium and molybdenum, and as a result these materials are often informally referred to as chromoly steel (common variaqnt stylings include chrome-moly, CrMo, CRMO, CR-MOLY, and similar). They have an excellent strength to weight ratio and are considerably stronger and harder than standard 1020 steel, but are not easily welded (need pre and post weld thermal treatment to avoid cold cracking).
While these grades of steel do contain chromium, it is not in great enough quantities to provide the corrosion resistance found in stainless steel.
Examples of applications for 4130, 4140 and 4145 include structural tubing, bicycle frames, tubes for transportation of pressurized gases, firearms receivers, clutch and flywheel components, and roll cages. 4150 stands out as being one of the steels accepted for use in M16 rifle and M4 carbine barrels by the United States military. These steels are also used in aircraft parts and therefore 41xx grade structural tubing is sometimes referred to as "aircraft tubing".
And a clip from an extensive article on gun steels from Peterson's Rifle Shooter:
"4140, also known as ordnance steel, was one of the early high-alloy steels, used in 1920s’ aircraft frames and automotive axles in addition to rifle barrels. It has about 1 percent chromium, 0.25 percent molybdenum, 0.4 percent carbon, 1 percent manganese, around 0.2 percent silicon and no more than 0.035 percent phosphorus and no more than 0.04 percent sulphur. That leaves most of it, 94.25 percent, iron.
Read more:
http://www.rifleshootermag.com/2011/...#ixzz2ONYpEd3H
"One of the characteristics of this class of steel is the ability to be case hardened by carburization of the surface. The core of the material retains its bulk properties, while the outside is significantly hardened to reduce wear and tear on the part. This makes this grade of steel an excellent material for such uses as gears, piston pins, crankshafts, and bike frames.[1]"
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03-22-2013, 02:05 PM
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