REF: S 752-13B A514 contains 8 compositional grades. 6 of these 8 Grades specify a boron addition range. For boron to be effective as a hardenability agent, it is conventional practice to add titanium to protect the boron from forming BN. Of the 6 Grades requiring boron additions, only two (Grades B and E) have required titanium ranges. Grade B has a 0.04% Ti maximum, and Grade E has a 0.10% Ti maximum. Three Grades (F. H, and P) have no titanium range specified, and one (Grade S) has a footnote limiting Ti additions at 0.06%. To be effective in removing free nitrogen from the steel composition, the Ti addition should be, at a minimum, stoichiometric to the nitrogen content. [Ti:N] = [3.4:1] To be safe, many steelmakers require a higher Ti:N ratio aim, for example, a 5:1 ratio of Ti:N. The 0.04% maximum Ti restriction unique to Grade B unduly restricts the steelmakers ability to safely meet the desired Ti:N ratio. As a result, the boron effectiveness can be compromised by this exceptionally restrictive Ti requirement of Grade B. Proposal: Change the Ti range of Grade B in Table 1 of A514/A514M to 0.01-0.10%, to be the same as Grade E.
Keywordsalloy; bridges; high-yield-strength; plates; quenched; steel; structural steel; tempered; welded construction ;
Ballot Item Approved as A514/A514M-2014 and Pending Publication