TOOL STEEL FOR THE UNITED STATES NAVY. 



By LBWis Hobart Kenney, B. S., M. E., Member. 



INTRODUCTION. 



Previous to 1909 each navy yard prepared requisitions for the purchase 

 of tool steels for its own purposes. The requisitions specified either that 

 proprietary material be purchased or that the award of contract be based on 

 information obtained by a test of some description on samples submitted by 

 the bidders. But by this method there could be no uniformity in the speci- 

 fications of the navy yards, so in order to centralize the purchasing and to 

 standardize the tool steels, a tool steel board, in 1909, recommended that 

 the Philadelphia Navy Yard be the purchasing station; and it prepared 

 specifications for one "high speed" and for three grades of carbon tool steel. 

 The specifications are given in Appendix A. 



The chemical composition of this "high speed" tool steel differed from 

 that of any of the commercial tool steels, but the chemical composition of 

 each grade of carbon tool steel corresponded to that of commercial tool 

 steels. The three grades of carbon tool steel varied principally in the carbon 

 content, in order to adapt them to the purposes for which such tool steels 

 are generally used. The contracts were awarded under these specifications 

 to the lowest responsible bidders for tool steel of a chemical composition 

 within the specification limits. The specifications required, as a part of the 

 inspection for acceptance of the material, physical tests in addition to chemi- 

 cal analyses; but these physical tests never gave satisfactory or decisive 

 results, and proved conclusively that it was advisable to revise the specified 

 chemical compositions. The specifications did not provide a means for 

 ascertaining the relative merits of the tool steels offered by the bidders or 

 for learning if there were tool steels superior to those within the hmits of 

 the chemical compositions specified. 



In order to overcome the above objections, it was considered advisable 

 to revise the specifications given in Appendix A. Such specifications should 

 require the bidders to submit samples of the tool steels which they offer. 

 The samples should be manufactured into tools and subjected to physical 

 tests devised to investigate their relative merits. The data thus obtained 

 should form the basis for recommending the award of contract. The chemi- 

 cal compositions should be given with maximum and minimum limits, in 

 order to indicate to the bidder the kind of tool steel required, but as the 



