Sl'KCIKK ATIONS FOR (1KAY-IKO.N CASTINGS. 



489 



Tensile Test. Where specified, this shall not run lesa than: 



Light castings 18,000 Ib. per sq. in. 



Medium castings 21,000 " 



Heavy castings 24,000 " 



5. Arbitration Bar. The quality of the iron going into castings under specification shall be 

 determined l>y nic.ins of the " Arbitration Bar." This is a bar ij in. in diameter and 15 in. long. 

 It sli.ill he prepared as stated further on and tested transversely. The tensile test is not recom- 

 mended, l)iii iii i MM' it is called for, the bar as shown in Fig. i, and turned up from any of the broken 

 pieces ot ill transverse test shall be used. The expense of the tensile test shall fall on the pur- 

 chaser. 



6. Number of Test Bars. Two sets of two bars shall be cast from each heat, one set from the 

 first and the other set from the last iron going into the castings. Where the heat exceeds twenty 

 tons an adtlit ional set of two bars shall be cast for each twenty tons or fraction thereof above this 

 amount. In case of a change of mixture during the heat, one set of two bars shall also be cast 

 for every mixture other than the regular one. Each set of two bars is to go into a single mold. 

 The bars shall not be rumbled or othetwise treated, being simply brushed off before testing. 



,"... ...^ 



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FIG. i. ARBITRATION TEST BAR. TENSILE TEST PIECE. 



7. Method of Testing. The transverse test shall be made on all the bars cast, with supports 

 12 in. apart, load applied at the middle, and the deflection at rupture noted. One bar of every 

 two of e ich set made must fulfil the requirements to permit acceptance of the castings represented. 



8. Mold for Test Bar. The mold for the bars is shown in Fig. 2. The bottom of the bar is 

 ^g in. smaller in diameter than the top, to allow for draft and for the strain of pouring. The 

 pattern shall not be rapped before withdrawing. The flask is to be rammed up with green molding 

 sand, a little damper than usual, well mixed and put through a No. 8 sieve, with a mixture of one 

 to'twelve bituminous facing. The mold shall be rammed evenly and fairly hard, thoroughly dried 

 and not cast until it is cold. The test bar shall not be removed from the mold until cold enough 

 to be handled. 



9. Speed of Testing. The rate of application of the load shall be from 20 to 40 seconds for a 

 deflection of o.io in. 



10. Samples for Analysis. Borings from the broken pieces of the " Arbitration Bar " shall 

 be used for the sulphur determinations. One determination for each mold made shall be 

 required. In case of dispute, the standards of the American Foundrymen's Association shall be 

 used for comparison. 



11. Finish. Castings shall be true to pattern, free from cracks, flaws and excessive shrinkage. 

 In other respects they shall conform to whatever points may be specially agreed upon. 



12. Inspection. The inspector shall have reasonable facilities afforded him by the manu- 

 facturer to satisfy him that the finished material is furnished in accordance with these specifications. 

 All tests and inspections shall, as far as possible, be made at the place of manufacture prior to 

 shipment. 



WROUGHT IRON. Wrought iron is made in a reverberatory furnace from pig iron or from 

 molten metal taken directly from the blast furnace. The hearth of the reverberatory furnace is 

 fettled with high grade iron ore or mill scale, which acts as an oxidizing agent for reducing the 

 impurities. The puddling process may be divided into four stages: First or melting down stage, 

 occupying about 30 minutes, during which the silicon and manganese are oxidized and a consider- 



