Mechanical Properties and Corrosion Resistance of Matching GMA Welded Jointfor Martensitic Stainless Steel Line Pipe

摘要

Low carbon type 12Cr line pipes with high corrosion resistance in the C02 and H2S environmentrnhave been developed, and they have come to be widely used in field applications of flow line andrngathering line. Conventionally, duplex stainless steel and super duplex stainless steel weldingrnconsumables have been applied for girth welding of these materials. In these cases, theirrnundermatching weld joint has been pointed out. The ordinary matching type gas metal arc weldingrn(GMAW) consumables have the inevitable problem of poor toughness. That is owing to the elevationrnof oxygen content in weld metal by invasion from active gases added to the shielding gas.rnGMA welding in the pure inert shielding gas has been investigated applying new matching typernconsumables. The girth welding trial of 12Cr line pipe with the pure inert gas was finalized with thernsatisfactory result. The microstructure of weld metal shows a martensitic structure, and overmatchingrnwas confirmed. No weld crack was observed by lowering carbon and nitrogen of the weldingrnconsumable. The toughness of weld metal reveals over 100J in Charpy V-notch impact test at-40℃.rnThe corrosion resistance of matching welded joint was same as base metal. The matching weldedrnjoint shows good SSC resistance and hydrogen embrittlement resistance.