948 REPORT—1890. 
2. On Aluminium Bronze for Artillery and Small Arms. 
By J. H. J. Dacecmr, F.C.8., F.C, 
As early as 1859-60, guns were cast in aluminium bronze by the French and 
Bavarian Governments, and favourably reported upon by the authorities; but the 
high price of aluminium at that time prevented its use for guns. 
The cost of aluminium bronze in 1860 was 4s. 11d. per lb. ; to-day it is on the 
market at 1s. 4d. per lb. 
The results of mechanical and physical tests point to the fitness of this alloy 
for artillery and small arms under the altered condition of explosives, the recent 
trials of artillery—using the smokeless powder—by the German authorities proving 
that steel guns were seriously injured by the new ammunition, and a return to 
bronze for guns is adyocated by their artillerists; but in the properties essential. 
to good gun-metal, aluminium bronze surpasses the ‘steel bronze’ or the tin 
bronze used in the Uchatius system of gun fabrication. The following table gives 
comparative tests of this alloy and aluminium bronze :— 
genie. Elastic limit} Elastic ex- | Ultimate Heals 
Alloy te ie rer pounds per / tension per |elongation oe Hardness 
sq. inch sq-inch /|unit length] per cent. per cent. 
Steel bronze (Sn 8: 43,200 5,672 00004 40 — 5: 
Cu 92°) cast in 
chilled mould 
Steel bronze from} 60,350 15,620 0:00306 16°5 44 20°(?) 
bore of gun (man- 
drelled). 
No.3 Al. bronze: Al.| 69,800 21,500 0:00133 32°8 32:1 13°46 
75, Si 0°75, Cu 
91°75, cast in 
chilled mould 
No. 1 Al. bronze: Al. | 114,514 —_ — 0°45 — —_— 
10: Si 1:0 Cu 89 
U.S. Ordnance .| 109,823 79,894 — 0:05 — 21:17 
Office tests . .| 111,400 84,000 — 650 — —_ 
probable 
Gun steel bs ; 98,134 57,796 — 16- — — 
Compression test of 
No. 1 Al. bronze 
at Watertown Ar- 
senal, 160,400 lbs. 
Tests have shown that aluminium bronze maintains its strength through a high 
range of temperature, being heated up to 500° F. without injury to its strength. 
No liquation or separation of the metals takes place, as is the case with tin bronze ; 
neither does it alter in composition or quality even after repeated remeltings, and 
so obsolete and unserviceable guns would still retain their value as scrap metal, 
and could readily be utilised for new ordnance. Its low melting point—1,600° 
to 1,700° F.—would be favourable to good results, using the Rodman method of 
cooling the casting from the inside. 
Its resistance to corrosion, its non-liability to crystallise under repeated shocks, 
as shown by a needle in a Springfield rifle bearing 11,000 discharges without 
being injured, would make it valuable for rifles and small arms. These alloys, 
having a tensile strength of 114,000 to 72,000 Ibs, per sq. inch, and elongation from 
nil to 40 per cent., and elastic limit from 20,000 to 80,000 lbs. per sq. inch, 
values likely to be increased by a process similar to those of Dean or Uchatius, 
would give us a gun which would probably stand the severest test service. 
The cost of a finished gun (at the present price of aluminium and copper) 
would be about 196/. per ton. 
