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Part 1: The Fracture Behavior of A588 Grade A and A572 Grade 50 Weldments

An experimental study was conducted on ASTM A588 Grade A and ASTM A572 Grade 50 microalloyed steels submerged arc welded with Linde 40B weld metal to determine the fracture properties of base plates, weld metal and heat-affected zones. The effects of plate orientation, heat treatment, heat input, and postweld heat treatments on heat-affected zone toughness were included in the investigation. Tensile properties were evaluated for the weld metal and base plates. Hardness tests were done on weld heat-affected zones (HAZ). Charpy impact tests were performed over a temperature range for plates, welds and heat-affected zones. The nil-ductility transition temperature was determined for the plates and the weld metal.

The weld metal tensile tests showed that the Linde 40B weld metal overmatched the baseplates in strength. Postweld heat treatment had minimal effect on either the strength or ductility of this weld metal.

Part 2: Effects of Long-Time Postweld Heat Treatment on the Properties of Constructional-Steel Weldments

Various code rules often require that welded structures such as pressure vessels, nuclear-power-plant supports, and offshore platforms be postweld-heat-treated (PWHT), depending on type and thickness of the weldment. The PWHT may be performed several times on a structure during fabrication, and the total time at elevated temperature may approach 100 hr in some situations. Because PWHT may, in some instances, result in loss in strength and degradation in toughness of the base metal, heat-affected zone (HAZ), or weld metal, the mechanical properties of the weldment may not meet customer or code specifications after PWHT.

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Published: 1988 Number of Pages: 32 File Size: 1 file , 1.3 MB