The most recent wording of 3.6.2 of E290-13 (The surfaces of the supports and plunger shall be harder than the material tested.) has met with the criticism that, in bending, the loads are such that even supports and plungers softer than the test piece will not reach yield and flatten. No flattening has been observed by users who test thin armor plate that is harder than the supports or plunger meeting 3.6.2 of E290-09, i.e., 20 HRC. For them, complying with 3.6.2 of E290-13 would be onerous, unnecessary, and costly.
Keywordsbend; crack; ductility; flattened bend; forming limit; fracture; free bend; guided bend; mandrel; pin; plunger; roller ;
Ballot Item Approved as E290-2014 and Pending Publication