Table 48 

 MECHANICAL PROPERTIES 



Iron and Iron Alloys 



III 



Composition, approximate: 



Electrolytic, C 0.0125 per cent; other impurities less than 0.05 per cent. 



Cast, gray: Graphitic, C 3.0, Si 1.3 to 2.0, Mn 0.6 to 0.9, S max. 0.1, P max. 1.2. 



A. S. T. M. Spec. A48 to 18 allows S max. 0.10, except S max. 0.12 for heavy castings. 

 Malleable: American " Black Heart," C 2.8 to 3.5, Si 0.6 to 0.8, Mn max. 0.4, S max. 0.07, P max. 0.2. 

 European " Steely Fracture," C 2.8 to 3.5, Si 0.6 to o.8, Mn 0.15, S max. 0.35, P max. 0.2. 

 Compressive Strengths [Specimens tested: 25.4 mm (1 in.) diam. cylinders 76.2 mm (3 in.) long]. 

 Electrolytic iron 56.5 kg/mm 2 or 80,000 lb/in 2 . 



Gray and malleable cajSt iron 56.5 to 84.5 kg/mm 2 or 80,000 to 120,000 lb/in 2 . 

 Wrought iron, approximately equal to tensile yield point (slightly above P-limit). 

 Density: 



Electrolytic iron 7.8 g/cm 3 or 487 lb/ft 3 Malleable iron see page 653 



Cast iron 7.2 g/cm 3 or 449 lb/ft 3 Wrought iron 7.85 g/cm 3 or 490 lb/ft 3 



Ductility: — Normal Erichsen values for good trade quality sheets, 0.4 mm (0.0156 in.) 



Thickness, soft annealed. Depth. 



mm in. 



Sheet metal hoop iron, polished 9.5 0.374 



Charcoal iron tinned sheet 7.5 o.2gs 



Second quality tinned sheet 6.7 0.264 



Modulus of elasticity in tension and compression: 

 Electrolytic iron ... . 17,500 kg/mm 2 or 25,000,000 lb/in 2 Malleable iron. . . see page 653 



Cast iron 10,500 kg/mm 2 or 15,000,000 lb/in 2 Wrought iron. . . . 17,500 kg/mm 2 or 25,000,000 lb/in 2 



Modulus of elasticity in shear: 



Electrolytic iron 7030 kg/mm 2 or 10,000,000 lb/in 2 Cast iron 8450 kg/mm 2 or 12,000,000 lb/io 2 



Wrought iron 7030 kg/mm 2 or 10,000,000 lb/in 2 



Scleroscope hardness values shown are as determined with the Shore Universal hammer. 

 Strength in Shear: 

 Electrolytic (remelt) Commercial wrought 



P-limit 8.4 kg/mm 2 or 12,000 lb/in 2 P-limit 21. 1 kg/mm 2 or 30,000 lb/in 2 



Ultimate strength 21. 1 kg/mm 2 or 30,000 lb/in 2 Ultimate strength. . 35.0 kg/ mm 2 or 50,000 lb/in 2 



Transverse strength, from flexure formula: 

 Gray cast iron 



Modulus of rupture, 33.0 kg/mm 2 or 47,000 lb/in 2 



"Arbitration Bar," 31.8 mm (ij in.) diameter, or 304.8 mm (12 in.) span; minimum central load at rup- 

 ture 1130 to 1500 kg (2500 to 3300 lb.); minimum central deflectionat rupture 2.5 mm (0.1 in.), (A. S. T. 

 M. Spec. A 48-18). 

 * Properties of Swedish iron (impurities less than 1 per cent) approximate those of electrolytic iron, 

 t These two values of B. h. n. only are as determined at 500 kg pressure. 

 X U. S. Navy specifies minimum tensile strength of 14.1 kg/ mm 2 or 20,000 lb/in 2 . 



|| From T. D. Yensen, University of Illinois, Engr. Exp. Station, Bulletin No. 83, 1915 (shows Si 4.40 as alloy of 

 maximum strength). 



f From T. D. Yensen, University of Illinois, Engr. Exp. Station, Bulletin No. 95, 191 7. 

 Smithsonian Tables. 



