ASSESSMENT OF ASTM A723 STEEL FOR CONSTRUCTING IMPULSIVELY LOADED VESSELS
Abstract
An alternate material for thick, e.g. greater than ~6 inches (152 mm), non-welded Explosive containment vessels (ECVs) cover forgings was investigated. ECVs are used to partially or fully contain the detonation products of explosives. Uses of ECVs include containment of suspect luggage at airports, bomb disposal, containment of dynamic experiments, and disposal of chemical munitions. The impulsive loading and dynamic response of ECVs necessitates the use of materials with high strength and high toughness to prevent ductile exhaustion and brittle fracture. Design rules for impulsively loaded vessels (ILVs), applicable to ECVs, were introduced into Section VIII, Division 3 of the ASME BPVC Code through Code Case 2564 in 2008. In 2019, the ILV design rules were incorporated into Section VIII, Division 3, and Code Case 2564 was annulled. Section KM-4 of Section VIII, Division 3 includes approved materials for vessel fabrication; however, many of these materials either do not exhibit the requisite mechanical properties for ECV applications or lack corresponding published mechanical testing data necessary for ECV design. Another compounding factor is the new guidance in Section KM-234.1 (ASME BPVC Section VIII, Division 3, 2023), which requires Charpy V-notch (CVN) testing 60 °C (108 °F) below the Minimum Design Metal Temperature (MDMT). For many applications, this will require ECV construction materials to exhibit high toughness at low temperatures. In the present study, ASTM A723 steel forgings have been investigated as a candidate material for ECV construction. Mechanical property data from industrially produced forged disks are presented including full CVN temperature-transition curves and tensile test results. Additionally, insight is provided on the effect of tempering temperature on mechanical properties of A723 Steel.