Steel material, and oil-well steel pipe for expansion

A technology of steel and steel pipes, applied in the field of oil well steel pipes for pipe expansion, can solve the problems of unfavorable economy, wider excavation area, large excavation cost and construction period, etc., and achieves excellent pipe expansion, high uniform elongation, and excellent SSC resistance. Effect

Inactive Publication Date: 2017-08-18
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, conventionally, when excavation was required to a high depth, the number of times of inserting the shell increased, so the excavation area in the outer diameter direction of the oil well in the surface layer of the formation became wider, and the excavation cost and construction period were huge, which was economically disadvantageous.

Method used

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  • Steel material, and oil-well steel pipe for expansion
  • Steel material, and oil-well steel pipe for expansion
  • Steel material, and oil-well steel pipe for expansion

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0149]In a 50 kg vacuum furnace, 23 kinds of steels, A to P and AA to AG having the chemical compositions shown in Table 1, were melted and cast into steel ingots. Each steel ingot was heated at 1180° C. for 3 hours, then forged, and cut by electric discharge cutting. Thereafter, soaking was performed at 1150° C. for 1 hour and hot rolling was performed to form a plate material with a thickness of 20 mm, and then solution heat treatment was performed at 1100° C. for 1 hour to obtain test materials (test numbers 1 to 23). In addition, the test materials produced in the same manner as test numbers 1 to 23 were further subjected to cold working with a working degree of 10% after the solution heat treatment to obtain test materials with improved strength (test numbers 24 to 46).

[0150] [Table 1]

[0151]

[0152] After examining the mechanical properties and metallographic structure of the above-mentioned test materials (Test Nos. 1 to 46), each test material was subjected t...

Embodiment 2

[0176] Using steels K, L, O, and AF prepared in Example 1, the influence of aging heat treatment after solution treatment was investigated. The conditions of the solution heat treatment were the same as in Example 1, and the conditions of the subsequent aging heat treatment were 800° C. for 1 hour. In addition, the method of the evaluation test is the same as that of Example 1.

[0177] As for the metallographic structure after the above-mentioned aging heat treatment, similarly to Example 1, the test materials before and after cold working with a working degree of 25% were investigated using a ferrite measuring instrument. As a result, for the test material before cold working, the BCC structure structure was not detected in any sample, and it was an austenite single phase. Therefore, in the table, only the volume amount of the structure having the BCC structure of the cold-worked test material is shown in volume % in the form of the BCC ratio. These results are shown in Ta...

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Abstract

This steel material has a chemical composition which includes, in mass%, 0.6-1.8% of C, 0.05-1.00% of Si, over 25.0% but not more than 45.0% of Mn, 0.003-0.06% of Al, not more than 0.03% of P, not more than 0.03% of S, 0.5-3.0% of Cu, not more than 0.10% of N, 0-2.0% of V, 0-3.0% of Cr, 0-3.0% of Mo, 0-1.5% of Ni, 0-0.5% of Nb, 0-0.5% of Ta, 0-0.5% of Ti, 0-0.5% of Zr, 0-0.005% of Ca, 0-0.005% of Mg, 0-0.01% of REM, and 0-0.015% of B, the remainder comprising Fe and impurities, and which satisfies [0.6<C-0.18V<1.44]. The steel material has: a metallographic structure which comprises an austenite single phase; a yield strength of at least 241 MPa; and a uniform elongation of at least 40%.

Description

technical field [0001] The present invention relates to steel materials and oil well steel pipes for pipe expansion, in particular to steel pipes having high pipe expandability and containing hydrogen sulfide (H 2 S) Steel materials excellent in sulfide stress crack resistance used in oil wells and natural gas well environments, etc., and oil well steel pipes for pipe expansion using the same. Background technique [0002] In the excavation of oil wells and natural gas wells (hereinafter, oil wells and natural gas wells are collectively referred to as "oil wells"), the following method is generally adopted: after the excavation hole reaches a specified depth, the shell is inserted and buried to prevent the pit wall from collapsing. Furthermore, the work of sequentially inserting casings with smaller outer diameters while digging is repeated further. Therefore, conventionally, when digging to a high depth is required, the number of times of casing insertion increases, so tha...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D8/02C22C38/58
CPCC21D8/0205C21D8/0226C21D8/0236C21D8/0263C21D9/46C21D2211/001C22C38/001C22C38/002C22C38/005C22C38/02C22C38/04C22C38/06C22C38/08C22C38/12C22C38/14C22C38/16C22C38/20C22C38/22C22C38/32C22C38/38C21D8/02C22C38/58
Inventor 小林宪司富尾悠索
Owner NIPPON STEEL CORP
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