Part 1: Axial load-controlled fatigue tests on steel specimens machined from welded assemblies of 1 1/2 in. thick plates were conducted to evaluate the through thickness (ST, Z-direction or short transverse) fatigue characteristics of a normalized steel used for the construction of offshore drilling rigs. Short transverse properties of steel are important because many welded joints require loads to be transferred through the thickness of a plate. When designing and fabricating such joints, the possibility of lamellar tearing during welding should be considered. In the series of experiments undertaken, no lamellar tearing was detected in the welded assemblies prior to final machining. Cylindrical specimens were cut from the welded assemblies and threaded at both ends so that loads could be applied parallel to the through thickness direction (normal to the rolling surface) of the test plate which was located in the center.
The steel, Grade EH 32 which conforms to American Bureau of Shipping standards, exhibited good static through thickness ductility (greater than 20% ROA). In comparison with the properties of the weld metal and the longitudinal direction of the plate, the through thickness section did not perform as well under complete load reversal (R = -1) in both high and low cycle loading.
Inspection of fracture surfaces with a scanning electron microscope clearly shows that non-metallic inclusions affect both the static and fatigue failure mechanisms in the short transverse direction. Fatigue crack initiations at the surface of flat inclusions running parallel to the rolling direction were observed in etched cross sections viewed through an optical microscope.
Simple hardness tests of plate cross sections appear to be useful indicators of the short transverse tensile and fatigue strengths, and are recommended as an economical method of evaluating the through thickness properties of steel plate.
Part 2: The objective of this report is to present a general picture of the properties of the steels used in current heavy walled nuclear reactors, based on the extensive data accumulated by the Industry Cooperative Program of the Pressure Vessel Research Committee of the Welding Research Council. These data are stored in a computer program, known as the HVYSTL program. The test specimens for this program were taken from actual production plates, forgings, and castings for nuclear contracts by utilizing nozzle cut-outs, crop ends and extra material ordered especially for this purpose. Therefore the data are representative of the properties of current nuclear reactor materials. The testing program included complete chemical analysis, tensile tests, Charpy V-notch impact tests, and drop weight NDT tests. Charpy test values consisted of absorbed energy in foot-pounds, percent shear fracture, and lateral expansion in mils for tests over the entire transition temperature range. In addition to the customary quarter thickness location, testing was also conducted on specimens from surface and center locations. These specimens were oriented both longitudinally and transversely with respect to the rolling direction of plates and tangentially and radially with respect to the surfaces of forgings.
| File Size : | 1
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| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 28 |
| Published : | 1976 |
