KR970015761A

KR970015761A - Yield strength 50kgf / mm² grade steel with excellent resistance to hydrogen organic cracking and hydrogen sulfide stress corrosion cracking

Info

Publication number: KR970015761A
Application number: KR1019950031684A
Authority: KR
Inventors: 주세돈; 박찬엽
Original assignee: 김종진; 포항종합제철 주식회사
Priority date: 1995-09-25
Filing date: 1995-09-25
Publication date: 1997-04-28
Also published as: KR100256350B1

Abstract

본 발명은 유정등지에서 생산되는 원유 및 천연가스를 정제시설까지 운송할때 쓰이는 라인파이프용 강재의 제조방법에 관한 것으로, 제강공정 중 Cu 및 Ni을 첨가하지 않고 진공탈가스(RH) 처리중에 Ca을 첨가하여 강의 성분을 적정범위로 조성하고 이와같이 조성된 강의 열간 압연조건 및 냉각조건을 적절히 제어하므로서, HIC 및 SSCC 저항성의 우수하고 항복강도가 50kgf/㎟급인 라인파이프용 강재를 제조할 수 있는 방법을 제공하고자 하는데, 그 목적이 있다.The present invention relates to a method for producing a line pipe steel used for transporting crude oil and natural gas produced in oil wells to a refining facility, and does not add Cu and Ni during the steelmaking process, but does not add Ca and Ni during vacuum degassing (RH) treatment. A method for producing line pipes having excellent yield strength and 50kgf / mm2 yield strength, by controlling the hot rolling and cooling conditions of the steel formed in such a manner that the composition of the steel is added to the proper range by adding the It is intended to provide a purpose.

상기한 목적달성을 위한 본 발명은 항복강도 50kgf/㎟급 라인파이프용 강재를 제조하는 방법에 있어서, 상기 강재의 제강공정중 Cu 및 Ni을 첨가하지 않고, 구상화처리(PI)된 용강의 진공탈가스 처리(RH) 공정 중 Ca을 첨가하여 강을 중량%로, C : 0.05∼0.12%, Si :0.5% 이하, Mn : 0.6∼1.5%, Al : 0.01∼0.1%, Ti : 0.005∼0.03%, Nb : 0.01∼0.05%, V : 0.01∼0.1%, S : 0.002% 이하, P : 0.02% 이하, N : 10∼100ppmm, O : 0.01∼0.05%, Ca : 10∼100ppm, 나머지 Fe 및 기타 불가피한 불순원소로 조성하는 단계; 상기와 같이 조성되는 강의 슬라브를 1050∼1300℃의 온도범위에서 가열한 후 재결정 영역에서 열간압연하고, 60∼80%의 압하량범위로 재결정온도 이하의 미재결정 영역에서 열간 압연하여 Ar₃±30℃의 온도범위에서 종료하는 열간압연 단계; 및 상온까지 공냉하는 냉각단계를 포함하여 이루어지는 수소유기균열 및 황화수소응력부식 균열 저항성이 우수한 항복강도 50kgf/㎟급 강재의 제조방법에 관한 것을 그 요지로 한다.The present invention for achieving the above object is a method for producing a steel sheet for yield strength 50kgf / ㎜ class line pipe, vacuum degassing of the molten steel that is spheroidized (PI) without adding Cu and Ni during the steelmaking process of the steel In the gas treatment (RH) step, Ca is added to the steel by weight, C: 0.05 to 0.12%, Si: 0.5% or less, Mn: 0.6 to 1.5%, Al: 0.01 to 0.1%, Ti: 0.005 to 0.03% , Nb: 0.01% to 0.05%, V: 0.01% to 0.1%, S: 0.002% or less, P: 0.02% or less, N: 10 to 100ppmm, O: 0.01 to 0.05%, Ca: 10 to 100ppm, remaining Fe and others Forming an inevitable impurity element; The slab of the steel formed as described above is heated at a temperature range of 1050 to 1300 ° C., and then hot rolled in a recrystallization region, and hot rolled in an unrecrystallized region below a recrystallization temperature in a rolling reduction range of 60 to 80% to give Ar ₃ ± 30. Hot rolling step of finishing in the temperature range of ℃; And a method for producing a yield strength of 50 kgf / mm 2 grade steel having excellent resistance to hydrogen organic cracking and hydrogen sulfide stress corrosion cracking, including a cooling step of air cooling to room temperature.

Description

Yield strength 50kgf / ㎠ grade steel with excellent resistance to hydrogen organic cracking and hydrogen sulfide stress corrosion cracking

본 내용은 요부공개 건이므로 전문내용을 수록하지 않았음Since this is an open matter, no full text was included.

제1도는 발명강과 비교강의 SSCC 저항성을 파단수명 응력비의 관계로 나타낸 그래프,1 is a graph showing the SSCC resistance of the inventive steel and the comparative steel as a relationship between the fracture life stress ratio,

제2도는 발명강과 비교강의 HAZ부의 SSCC 저항성을 파단수명-응력비의 관계로 나타낸 그래프.2 is a graph showing the SSCC resistance of the HAZ portion of the inventive steel and the comparative steel in terms of fracture life-stress ratio.

Claims

In the method of manufacturing a yield strength 50kgf / mm2 line pipe steel, Ca in the vacuum degassing (RH) process of molten steel that is spheroidized (PI) without adding Cu and Ni during the steelmaking process of the steel Steel by weight%, C: 0.05 to 0.12%, Si: 0.5% or less, Mn: 0.6 to 1.5%, Al: 0.01 to 0.1%, Ti: 0.005 to 0.03%, Nb: 0.01 to 0.05%, V 0.01 to 0.1%, S: 0.002% or less, P: 0.02% or less, N: 10 to 100 ppm, O: 0.01 to 0.05%, Ca: 10 to 100 ppm, remaining Fe and other inevitable impurities; The slab of the steel formed as described above is heated at a temperature range of 1050 to 1300 ° C., and then hot rolled in a recrystallization region, and hot rolled in an unrecrystallized region below a recrystallization temperature in a rolling reduction range of 60 to 80% to give Ar ₃ ± 30. Hot rolling step of finishing in the temperature range of ℃; And a method for producing a yield strength of 50 kgf / mm 2 grade steel having excellent resistance to hydrogen organic cracking and hydrogen sulfide stress corrosion cracking, including a cooling step of air cooling to room temperature.

※ Note: The disclosure is based on the initial application.