78 The N.Z. Journal of Science and Technology. [Mar. 
Sulphur is the cause of brittleness and cracking, and is the most 
objectionable element common in steel castings : 008 per cent, is the 
maximum allowable. 
Manganese renders steel hard and brittle, and an excess should be 
avoided. As, however, it reduces the bad effect of sulphur it should be 
present to the extent of, say, ten times the sulphur percentage up to a 
maximum of 1 per cent. 
Aluminium is an excellent deoxidizer, and therefore makes for sound 
castings free from gas-holes. About 0*02 per cent, should be added as 
ferro-aluminium just before pouring or when in the ladle. 
Titanium is a deoxidizer, and also burns out the nitrogen. It therefore 
makes for sound castings, but also seems to improve the strength and 
ductility of the metal. About 0*01 per cent, should be added as ferro- 
titanium at the same time as the aluminium. 
Tensile strength increases with the carbon, so that if it is too high 
it is an indication that too much carbon is present, and brittleness and 
unreliability may be looked for. Under New Zealand conditions particularly 
it is wise to look for a steel of moderate strength, and to remember that 
the mere strength is no criterion of quality. The best steel for resisting 
shocks goes about 28 tons per square inch, and a minimum of 26 tons may 
safely be insisted on. But it is more important to specify a maximum, and 
32 tons per square inch should be the limit. The following table shows 
representative foreign specifications and analyses. 
Representative Analyses for Steel Castings. 
(The percentages marked * are maximums.) 
Source. 
Carbon. 
Silicon. 
Manganes ■. 
Sulphur. 
Phosphorus. 
1 
Tensile 
Strengtli: 
Tons per 
Square Inch. 
Percentage of 
Elongation 
in 2 in. 
Specification— 
British Standards Committee . . 
, # 
, , 
. . 
•07* 
•07* 
26 (min.) 
• • 
Am. Soc. for Testing Materials, 
1914— 
Ordinary castings . . 
•30* 
• • 
. . 
• . 
•06* 
. . 
. . 
Special castings—Hard 
) 
( 
35 (min.) 
15 
,, Medium . . 
. . 
•05* 
•05* \ 
31 „ 
18 
,, Soft 
1 
/ 
1 
27 „ 
22 
U.S. Navy, 1917— 
Grade A—-Wearing parts only 
. . 
•05* 
•05* 
35 (min.) 
17 
,, B—Subject to shocks 
. . 
. . 
. . 
•05* 
•06* 
27 
22 
,, C—Fittings not need- 
ing strength 
• . 
. . 
. . 
•07* 
•06* 
. . 
Natal Government . . 
, , 
. . 
. . 
, , 
• • 
28-32 
. . 
Caledonian Railway . . 
. # 
. , 
. , 
32 (max.) 
. , 
Average practice, Milwaukee con- 
verter castings 
•20 
•20 
•14 
•04 
•04 
25-29 
• . 
,, American r a i 1- 
way castings 
•27 
•25 
•57 
•03 
•05 
26-35 
• • 
Crucible casting made at Knapp’s 
•75 
•30 
•33 
•02-09 
•02-06 
• * 
To recapitulate : Unless steel can be regularly cast to approach the 
following specification it is idle to hope for success :— 
Analysis. —Carbon, 0-15 to 0-30 per cent. ; silicon, 0*10 to 0*30 per 
cent.; manganese, 0T0 to 0-80 per cent.; sulphur, 0*03 to 0*08 per 
cent. ; phosphorus, 0*03 to 0*08 per cent. 
Tensile Strength. —26-32 tons per square inch. 
Elongation .—Not less than 15 per cent, on 2 in. (British standard 
specimen to be used.) 
