US 12,240,066 B2
Weld joints involving dissimilar metals and methods for forming same
William Randal Bunker, Conroe, TX (US); Helna George, Houston, TX (US); and Rajagopala N. Pillai, Pasadena, TX (US)
Assigned to National Oilwell Varco. L.P., Houston, TX (US)
Appl. No. 17/427,568
Filed by National Oilwell DHT, L.P., Conroe, TX (US)
PCT Filed Feb. 11, 2020, PCT No. PCT/US2020/017704
§ 371(c)(1), (2) Date Jul. 30, 2021,
PCT Pub. No. WO2020/172005, PCT Pub. Date Aug. 27, 2020.
Claims priority of provisional application 62/808,422, filed on Feb. 21, 2019.
Prior Publication US 2022/0143734 A1, May 12, 2022
Int. Cl. B23K 9/23 (2006.01); B23K 9/028 (2006.01); B23K 103/04 (2006.01); C21D 9/50 (2006.01); E21B 17/042 (2006.01)
CPC B23K 9/23 (2013.01) [B23K 9/0282 (2013.01); C21D 9/50 (2013.01); B23K 2103/05 (2018.08); E21B 17/042 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A method of welding to join a high-strength low alloy steel first member to a stainless steel second member, the method comprising:
buttering a first joint surface on the b-strength low alloy steel first member, wherein buttering comprises:
preheating the first joint surface;
welding a border layer of weld material to the first joint surface; and
heat treating the border layer and the first joint surface after welding the border layer; and
forming a weld between the alloy steel first member and the stainless steel second member after heat treating the border layer and the first joint surface, the forming comprising:
preheating the border layer and preheating a second joint surface on the stainless steel second member; and
adding a body of weld material between the border layer and the second joint surface.