Experimental Investigation of Structural Performance of Welded Interfaces Between Steel Castings and Steel Hollow Structural Sections

Abstract

This paper presents research examining the performance of different weld details between cast steel components and round hollow structural sections (HSS). The research, performed at the University of Arizona (UA) and overseen by the Steel Founder’s Society of America (SFSA), involves industry partnership with the American Institute of Steel Construction (AISC) and the American Welding Society (AWS). The research program investigates several cast welded interface details, including partial joint penetration (PJP) welds for modular cast nodes accepting an assortment of HSS thicknesses; and complete joint penetration (CJP) welds for matching casting and tube thickness. Essential weld variables in the study include root gap, groove angle, joint geometry, and backing bar treatment. Casting variables include machined or as-cast surfaces and an integrated backing bar configuration. The specimen is a double ended A8630 casting, welded on either side to round A500C HSS 6x½ sections. HSS stubs were first welded to castings to perform PQR qualification, including Radiographic (RT), Ultrasonic (UT), tension and side bend tests. Full-scale specimens were then subjected to monotonic and fatigue four-point bending tests that creates a pure moment condition on the welded interface. The weld and heat affected zones (HAZ) of the HSS and casting were carefully instrumented with inelastic strain gages. Finite element analysis involving solid modelling of the weld interface geometry is used to relate performance to the local stress/strain state at the welds, as well as provide vital measurements for inaccessible inside diameter locations. Test results obtained include strength, ductility, and fatigue life. Good performance of several cast to weld interface details was observed. The ultimate objective of the study is to develop prequalified weld details for steel castings in tubular construction.