High-strength stainless steel seamless pipe for oil well pipe and manufacturing method thereof

Abstract

The present invention provides a stainless steel seamless steel pipe for oil country tubing that has a wall thickness greater than 25.4 mm, is 110 ksi (758 MPa) or higher, has a vE-10 of 40 J or higher, and has excellent corrosion resistance in a high-temperature corrosion environment. A steel raw material is heated and hot-rolled to form a seamless steel pipe. The steel raw material has the following composition: in mass %, C: 0.005-0.06%, Si: 0.05-0.5%, Mn: 0.2- 1.8%, Cr: 15.5~18.0%, Ni: 1.5~5.0%, V: 0.02~0.2%, Al: 0.002~0.05%, N: 0.01~0.15%, O: 0.006% or less, and satisfy Cr+0.65 Ni+0.60Mo+0.30W+0.55Cu-20C≥19.5, Cr+Mo+0.50W+0.30Si-43.5C-0.4Mn-Ni-0.3Cu-9N≥11.5 containing Mo: 1.0~3.5% , W: 3.0% or less, and Cu: 3.5% or less. At this time, the hot rolling is hot rolling in which the total rolling ratio in the temperature range of 1100 to 900° C. is 30% or more. After completion of the hot rolling, cooling is performed at a cooling rate higher than air cooling, and quenching and tempering treatment is further performed.

Description

technical field [0001] The present invention relates to a seamless steel tube for Oil Country Tubular Goods, in particular to a high-strength stainless steel seamless tube with excellent low-temperature toughness and excellent corrosion resistance. Background technique [0002] In recent years, in response to rising crude oil prices and the expected exhaustion of petroleum resources in the near future, undiscovered deep oil fields have been actively developed around the world. Strongly corrosive sour gas fields that have been abandoned for the time being. For such oil fields and gas fields, the depth is usually deep, and the atmosphere is also high temperature and contains CO 2 , Cl - And other harsh corrosion environment (corrosion environment). Therefore, as steel pipes for oil wells used in the exploitation of such oil fields and gas fields, steel pipes with high strength and excellent corrosion resistance are required. [0003] containing CO 2 , Cl - 13% Cr martens...

AI Technical Summary

Problems solved by technology

In the technology described in Patent Document 2, there is a problem that toughness is lowered in the case of a thick wall exceeding 25.4 mm, and the desired high toughness and high strength cannot be achieved at the same time.

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