Tension Test Specimen for Gray iron and Ductile Iron Castings

Tensile strength is the most important physical property for inspecting gray iron and ductile iron castings. Tension test specimen is also called as tensile bar, or tensile test bar. 

Although there are some standards that stipulating the dimensions of tension test specimen, however, it is difficult for casting buyers to send the requirements for test bars to their suppliers. Sometimes, the buyers need their suppliers to provide some test bars, and entrust the third party to perform the test, so they need to know what kinds of test bars commonly used.

The followings are the drawings for gray iron and ductile iron castings. Because of the difference of materials, the test specimen of grey cast iron is different with that of ductile cast iron. Briefly, the gray iron tensile bar is larger than ductile iron tensile bar. Therefore, in order to make the test machine to hold the test bar more firm, a simple screw thread, normally 1mm tooth space, will be necessary.

The test specimen of gray iron is diameter 20mm +/-0.1, the ductile iron bar is diameter 14mm +/-0.1. As for the other dimensions, please see the following drawings.

Ductile Iron Tensile Test Bar

Gray Iron Tensile Test Bar

The above tension test specimens are made during production with the castings, but not cut from the castings. If you want to cut a specimen directly from the castings, then you may need smaller tensile bars, such as diameters 5mm, 7mm, or 10mm.