508 



ENGINEERING MATERIALS. 



CHAP. XV. 



TENSILE PROPERTIES. 



(b) The yield point shall be determined by the drop of the beam of the testing machine. 



9. Modifications in Elongation, (a) For plain and deformed bars over f in. in thickness 

 or diameter, a deduction of I from the percentages of elongation specified in Section 8 (a) shall be 

 made for each increase of f in. in thickness or diameter above f in. 



(b) For plain and deformed bars under ^ in. in thickness or diameter, a deduction of i from 

 the percentages of elongation specified in Section 8 (a) shall be made for each decrease of - in. in 

 thickness or diameter below y^ in. 



10. Bend Tests. The test specimen shall bend cold around a pin without cracking on the 

 outside of the bent portion, as follows: 



BEND TEST REQUIREMENTS. 



EXPLANATORY NOTE: d = the diameter of pin about which the specimen is bent; 

 t = the thickness or diameter of the specimen. 



11. Test Specimens, (a) Tension and bend test specimens for plain and deformed bars 

 shall be taken from the finished bars, and shall be of the full thickness or diameter of material as 

 rolled; except that the specimens for deformed bars may be machined for a length of at least 9 in., 

 if deemed necessary by the manufacturer to obtain uniform cross-section. 



(b) Tension and bend test specimens for cold-twisted bars shall be taken from the finished 

 bars, without further treatment; except as specified in Section 2 (b). 



12. Number of Tests, (a) One tension and one bend test shall be made from each melt of 

 open-hearth steel, and from each melt, or lot of ten tons, of Bessemer steel; except that if material 

 from one melt differs f in. or more in thickness or diameter, one tension and one bend test shall be 

 made from both the thickest and the thinnest material rolled. 



(b) If any test specimen shows defective machining or develops flaws, or if a tension test 

 specimen breaks outside the middle third of the gage length, it may be discarded and another 

 specimen substituted. 



IV. PERMISSIBLE VARIATIONS IN WEIGHT. 



13. Permissible Variations. The weight of any lot of bars shall not vary more than 5 per 

 cent from the theoretical weight of that lot. 



1 See Section 9. 



