Exxonmobil Research and Engineering Company

Exxonmobil Upstream Research Company

Nathan Eugene Nissley

Douglas Paul Fairchild

Steven Jeffrey Ford

Mario Luis Macia

Hyun-Woo Jin

Amit Kumar

Adnan Ozekcin

Raghavan Ayer

Nicholas E Biery

Weld metals and methods for welding ferritic steels are provided. The weld metals have high strength and high ductile tearing resistance and are suitable for use in strain based pipelines. The weld metal contains retained austenite and has a cellular microstructure with cell walls containing lath martensite and cell interiors containing degenerate upper bainite. The weld metals are comprised of between 0.02 and 0.12 wt % carbon, between 7.50 and 14.50 wt % nickel, not greater than about 1.00 wt % manganese, not greater than about 0.30 wt % silicon, not greater than about 150 ppm oxygen, not greater than about 100 ppm sulfur, not greater than about 75 ppm phosphorus, and the balance essentially iron. Other elements may be added to enhance the properties of the weld metal. The weld metals are applied using a power source with current waveform control which produces a smooth, controlled welding arc and weld pool in the absence of COor oxygen in the shielding gas.

High toughness weld metals with superior ductile tearing resistance

Provided are butt welds and methods of making such butt welds using a combination of fusion root welding and friction stir welding to yield welds with decreased propensity for dropout during friction stir welding without the need for a back-up support plate. In one form of the present disclosure, the butt weld includes: two or more abutting structural steel components beveled on faying surfaces on one side of the components to form a suitably shaped fusion root weld groove and unbeveled on faying surfaces on the opposite side of the components and interconnected with a first fusion root weld on the beveled side of the components and a second friction stir weld on the unbeveled side of the components, wherein the first fusion root weld has a width ranging from 7 mm to 30 mm, a penetration depth ranging from 2 mm to 20 mm, and an overfill ranging from 2 mm to 5 mm, and wherein the stir zone of the second friction stir weld penetrates the first fusion root weld. The butt welds and methods of making find application in joining linepipe for oil and gas production.

Butt weld and method of making using fusion and friction stir welding

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Houston, TX, United States of America

Nathan Eugene Nissley