Effects of Preheat on Weldments of NICOP Steel.
NAVAL POSTGRADUATE SCHOOL MONTEREY CA
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Shielded metal arc weldments of Armco Steel Corporations NICOP class 3, 19mm 34 inch plate, conforming to ASTM A710 grade A, were studied to provide information concerning the microstructure in the heat affected zone HAZ of weldments fabricated with and without preheat. Microhardness, scanning electron microscopy and transmission electron microscopy were used to determine the effect of preheating on the microstructure. Similar microstructures in the preheat and non-preheat samples were observed. The microstructures were polygonal and acicular ferrite in the base and baseHAZ regions and increasing amounts of bainite and auto tempered martensite islands near the fusion line. From the point of view of microstructure, NICOP appears to be weldable without preheating.
- Properties of Metals and Alloys
- Fabrication Metallurgy