358 



TOOL STEEL FOR THE UNITED STATES NAVY. 



7. Each test piece shall then have ground off one end by wet emery 

 grinder an amount at least equal to one-half the thickness of the test piece, 

 leaving the end after grinding a V-shape. This V-end shall then test "file 

 hard." Each bar faihng in this test shall be rejected and another bar 

 furnished in its stead by the contractors, and failure of ten per cent of the 

 bars in any lot to meet this test shaU reject that lot. 



8. Chemical analyses shall be taken and the steel of each lot shall show 

 the following maximum and minimum limits for the elements named : — 



There shall be no other impurities or ingredients, except iron, particu- 

 larly no molybdenum. 



9. From each lot of tool steel one or more tools shall be forged and 

 treated with the standard high-heat treatment and ground to a uniform 

 standard shape of cutting edge for lathe tools; these tools shall be given a 

 standard twenty-minute test on a steel forging of the following chemical 

 and physical characteristics, viz., to be open-hearth, either nickel or carbon 

 steel, annealed: — 



Minimum tensile strength, 80,000 pounds. 



Minimum elastic limit, 50,000 pounds. 



Minimum elongation in 2 inches (cold bend about an inner diameter 

 of I inch through 180 degrees), 25 per cent. 



Maximum phosphorus, 0.06 per cent. 



Maximum sulphur, 0.04 per cent. 



The lathe tool, known as the standard |-inch tool, shall be able to take 

 a cut of A-inch depth, with iV-inch feed, at surface speed of 60 feet per 

 minute. 



