36o TOOL STEEL FOR THE UNITED STATES NAVY. 



Per cent. Per cent. 



Carbon 90 to i.oo 



Silicon 20 to .25 



Manganese 20 to .25 



Phosphorus, not more than 020 



Sulphur, not more than 025 



Vanadium, as desired. 



Physical Test. — End-milling cutter shall be made up from i-inch selected 

 at random bars and be tested on mild steel, the cut to be f of an inch wide 

 and tV of an inch in depth; at the rate of 85 revolutions per minute the 

 cutter shall travel not less than 30 inches without serious injury to the blade. 

 The second trial shall then be made with the same cut as above at the rate 

 of 150 revolutions per minute. The cutters shall travel at least 15 inches. 

 Hand taps shall be made up from ^ inch bar and tested on yV-inch grade " A " 

 tool steel, oil hardened, and the taps shall thread cleanly at least three holes. 

 Quarter-inch screw dies shall be tested on drill rod steel and at 150 revo- 

 lutions per minute shall cut 36 inches. 



Grade "C" 



For chisels, for hot and cold work, rivet punches, die blocks, shear 

 blades, structural work, blacksmith's tools, hand bars, etc. 



Grade "C" tool steel shall have a chemical composition approximately 

 as follows : — 



Per cent. 



Carbon, not less than 90 



Silicon, not less than 15 



Manganese, not less than 15 



Phosphorus, not more than 030 



Sulphiur, not more than 030 



Physical Tests. — Samples submitted under Grade " C " shall be made up 

 into machine chisels, structural steel punches, and flat drills. The chisels 

 (side cutting type) shall be tested on mild steel plates f inch thick, the depth 

 of cut to be I inch, and the length of cut shall in no case be less than 9 feet. 

 Samples shall be taken at random from the chipping blanks and made up 

 into cape chisels and shall be tested on nickel steel plates 2 inches in thickness 

 and shall cut through the plate for a distance of at least 3 inches without 

 serious injury to the chisel. The structural steel punches, f inch in diameter, 

 shall be tested on mild steel plates A inch thick, and they shall punch not 

 less than 600 holes at the rate of 60 holes per minute. 



