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INTERNAL STRAINS IN GUN FORGINGS,
INTERNAL STRAINS IN GUN FORGINGS.
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Internal strains were introduced by heating the, forgings and cooling the same rapidly by quenching from the bore.
These determinations were made upon the metal from the tubes of 5-inch K. F. guns.
The initial temperature of the tubes at the time of quenching was generally between 850° and 900° F., with a rate of flow for the water of about 100 gallons per minute. Where more than one set of determinations appear for the same tube it indicates that the metal had been re-treated or annealed between operations.
The numbers of the several tubes, with the compression stresses corresponding to the strains found in the rings next the bore of the forgings, are shown in the following table:
No. of tube.	Compressive stress next the bore per square inch.		Remarks.
	Breech end.	Muzzle end.	
11*249 Bo		Pounds. 44,300	Pounds. 49,000 27,800	Discard, §״. Muzzle crop end after second annealing at 360° F.
11272 B-j BM	35,500 29,700 25,200		
			
			
11363 B!		35;900 43.500 40.500 36.200 35,900 40.200 33,000	18,800 36,700 42,400	Discard, !״.
11363 B!‘				
11363 BÒ				
			Discard,
11363 B"			37,500	
11467 B!			39,900	
11775 BÒ			35,300	Discard, §".
11775 Bo		/ 26,000 \ 22,800	42.600 44,500 27,000 24,900 25.600 38.600 34,100	
11775 B4 MM				
11775 B¡ MO				
11775 B¡ MI				
11784 Bj		47,600		
11784 B¡		16;800 15,900 40,100 19,400 30,300		
11784 B!			14,900 23,000	665° F.
11784 B!‘				
11784 B\				
11784 B3 BM				650° F.
11784 B3 BO—A		24,000 17.200 23,300 31.700 22.700 43,800 31.200		
11784 B3BM A				
11791 B!			25,600	Discard,
11791 Bj			28,100 26,000	
11791 B¡					After annealing at 650° F.
11791 Bo			' 42, 400	
11794 B¡			82,500	Discard,
11794 Bl		47,000	42,100	
11794 B's		25, 700		
11837 B3		55,500 36,100 29,300 25,800 . 20,200	17,400	665° F.
11837 B3			45,000	
12485 B~ BI ״.			
12485 B7 BM				
12485 B- BJ—A			
12485 B7 BM A	26i 300 23,300		Annealed at 600° F.
12485 B7 BO A 				Annealed at 450° F.
20691 B3		34,100	43,200	
20691 Hi 		45,000	15,400