EP1521856B1 - Martensitic stainless steel seamless pipe and a manufacturing method thereof - Google Patents

Martensitic stainless steel seamless pipe and a manufacturing method thereof Download PDF

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EP1521856B1
EP1521856B1 EP03741248.3A EP03741248A EP1521856B1 EP 1521856 B1 EP1521856 B1 EP 1521856B1 EP 03741248 A EP03741248 A EP 03741248A EP 1521856 B1 EP1521856 B1 EP 1521856B1
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pipe
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EP1521856A1 (en
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Shigeru c/o Sumitomo Metal Industries Ltd Kidani
Mutsumi c/o Sumitomo Metal Industries Ltd TANIDA
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Nippon Steel Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with copper
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/10—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies
    • C21D8/105—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of tubular bodies of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/46—Ferrous alloys, e.g. steel alloys containing chromium with nickel with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/48—Ferrous alloys, e.g. steel alloys containing chromium with nickel with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54—Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron

Definitions

  • the present invention relates to a martensitic stainless steel seamless pipe, such as a pipe for an oil well, which ensures no generation of cracks resulting from a delayed fracture.
  • the present invention also relates to a method for manufacturing such a martensitic stainless steel pipe without any generation of inner surface defects such as internal scabs.
  • a martensitic stainless steel such as API-13% Cr which is used as a pipe for an oil well, normally includes a carbon content of about 0.2%, which needs a high yield strength of 80 ksi (552 MPa) or more and a hot workability. Due to a high C and Cr content, an as-rolled stainless steel pipe has an extreme hardness, therefore has a reduced toughness. Consequently, an as-rolled conventional martensitic stainless steel pipe might have a crack resulting from a delayed fracture in "the impact-worked portion", where an impact load or static load was worked before a heat treatment. Accordingly, it is necessary to restrict the piling height in "a rack” and/or the dropping height into a rack of the steel pipes during transportation or storage. Moreover, the stand-by time before a heat treatment after hot-rolling must be shortened.
  • Japanese Patent Unexamined Publication No. H8-120415 discloses a martensitic stainless steel having a restricted N content.
  • this patent specification only the improvement of toughness after a heat treatment is described.
  • neither the relationship between the N content and a delayed fracture in the impact-worked portions of an as-rolled steel pipe nor the measures for suppressing such inner surface defects as internal scabs due to poor hot workability resulting from the decreased N content is described. It is not practical to manufacture a seamless steel pipe without any measures to suppress internal scabs.
  • EP1099772 discloses a martensitic stainless steel for seamless steel pipes, such as oil well pipes, excellent in descaling property and machinability.
  • Japanese Patent Unexamined Publication No. H6-306551 discloses an invention, in which the hydrogen content is restricted to improve the toughness in the heat affected zone by welding of a martensitic stainless steel pipe having low carbon content. Furthermore, Japanese Patent Unexamined Publication No. H5-255734 describes an invention of dehydrogenating a martensitic stainless steel having low carbon content in order to prevent a delayed fracture. These inventions deal with a martensitic stainless steel having low carbon content. However, no description is given regarding the relationship between the hydrogen content and a delayed fracture in the impact-worked portions of an as-rolled martensitic stainless steel pipe containing such high C of about 0.2%.
  • the present inventors have attained the first objective by restricting the correlation of the contents of C (carbon), H (hydrogen), N (nitrogen) and S (sulfur) in addition to specifying the contents of various elements in steel properly.
  • the present inventors have attained the second object by specifying the condition to roll a steel pipe.
  • the present invention is characterized by the following martensitic stainless steel (A) and the following method (B) for manufacturing martensitic stainless steel.
  • “%” implies “mass %” regarding a content of each element.
  • “as-rolled pipe” means a pipe which is formed by a hot rolling and to which a heat treatment has not been applied yet.
  • the steel pipe has a C content of 0.18 to 0.21%, a Si content of 0.20 to 0.35%, a Cr content of 12.40 to 13.10%, a S content of 0.003% or less, and a N content of 0.035% or less, by mass.
  • the chemical composition of the martensitic stainless steel pipe according to the invention is determined as follows.
  • C provides a solid-solution hardening of an as-rolled steel pipe together with N.
  • the content of C should be 0.22% or less, and is preferably 0.21% or less, in order to suppress the delayed fracture of the impact-worked portions by the solid-solution hardening.
  • a reduced C content makes it difficult to attain the aimed mechanical strength after a heat treatment.
  • an excessive reduction in the C content causes internal scabs generated after making a steel pipe due to ⁇ -ferrite since C is an austenite-generating element.
  • the content of C should be 0.15% to 0.22%, and the content of effective solute C should satisfy the inequality (1) above. The reason for this will be explained later. It is preferable that the C content is 0.18% or more.
  • Si is added as deoxidant during steel making.
  • a content of less than 0.1% provides no effect on deoxygenating whereas more than 1.0% causes a low toughness. Accordingly, the content should be 0.1 to1.0%.
  • a preferable content is 0.75% or less in order to obtain a high toughness.
  • a more preferable content is 0.20 to 0.35%.
  • Mn is an element effective for enhancing the mechanical strength of steel, and is added as a deoxidant during steel making. In addition, it fixes the S in steel by forming MnS, and causes a good hot workability. A content of less than 0.10% provides no effect on a hot workability, whereas more than 1.00% causes a low toughness. Accordingly, the content should be 0.1 to 1.0%. It is preferable that the Mn content is 0.7% or less.
  • Cr is a basic element for enhancing a corrosion resistance of steel.
  • a content of more than 12.00% improves a corrosion resistance for a pitting, and further greatly enhances a corrosion resistance under a CO 2 environment.
  • the Cr content of more than 14.00% is apt to generate ⁇ ferrite in the process at a high temperature, causing a reduced hot workability.
  • an excessive Cr content results in high cost of production. Accordingly, the content should be 12.00% to 14.00%, and is more preferably 12.40% to 13.10%.
  • P is an impurity contained in steel.
  • An excessive P content causes a low toughness of products after a heat treatment.
  • An allowable upper limit of the P content should be 0.020%. It is preferable to minimize the P content as small as possible.
  • S is an impurity that decreases a hot workability
  • the S content should be minimized.
  • An allowable upper limit of the S content is 0.010%.
  • the S content should satisfy the inequality (5) above. It is preferable that the S content is 0.003% or less.
  • N is an austenite-stabilizing element that improves the hot workability of steel.
  • N causes a delayed fracture in the impact-worked portions of an as-rolled steel pipe.
  • the upper limit of the N content should be 0.05%.
  • the reduction in a hot workability resulting from a decreased N content is compensated by other elements, so that the N content should be minimized. It is preferable that the N content is 0.035% or less.
  • the content of O should be minimized to be 0.0060% or less.
  • the V, content should be 0.005 to 0.200%, and optionally at least one element selected from Nb:0.005 to 0.200%, Ti:0.005 to 0.200% and B:0.0005 to 0.0100% may be further contained.
  • the total amount of V, Nb, Ti, B should be 0.005 to 0.200% in case of including in addition to V, one or more kinds of these alloying elements.
  • Al can be added when deoxygenating during the steel making process and is effective for suppressing an external scab in a steel pipe.
  • an excessive Al content causes a reduced cleanness of steel and also causes clogging of an immersion nozzle in the process of a continuous casting. Accordingly, it is preferable that the Al content is 0 to 0.1%.
  • Ni is an austenite-stabilizing element and improves the hot workability of steel.
  • an excessive Ni content causes a reduced sulfide stress corrosion cracking resistance. Accordingly, the Ni content is 0 to 0.5%.
  • Cu is effective for enhancing corrosion resistance and is an austenite-stabilizing element to improve the hot workability of steel.
  • Cu has a low melting point, and an excessive Cu content causes a reduced hot workability. Accordingly, the Cu content is 0 to 0.25%.
  • Ca combines with S in steel and prevents a sulfur segregation in grain boundaries, which caused a reduced hot workability.
  • an excessive Ca content causes macro-streak-flaws. Accordingly, the Ca content is 0 to 0.0050%.
  • the present inventors studied the effect of C and N on a delayed fracture in the impact-worked portions of an as-rolled API-13% Cr steel pipe.
  • a delayed fracture test an impact load was applied to the steel pipes whose conditions will be described in "EXAMPLES”.
  • the results are shown in Fig. 1 and Tables 1 to 4, in which an effective solute carbon content (C*) and an effective solute nitrogen content (N*) were used. The reason for using C* and N* is described below.
  • C atoms combine with Cr atoms to form carbides.
  • the content of C, acting as an interstitial element, can be obtained by subtracting the content of C in the carbide from the total content of C. Accordingly, an effective solute carbon content (C*) is defined by the equation (6).
  • N an effective solute nitrogen content (N*) is defined by the equation (7).
  • N* an effective solute nitrogen content (N*) is defined by the equation (7).
  • Nb and V nitrides because of the lower precipitation temperature and a coefficient of 1/2 for Ti, B and Al nitrides because of the higher precipitation temperature.
  • Both C and N are interstitial elements in steel. If they have the same content, they provide approximately the same influence on the mechanical strength and the hardness. However, the content of C is restricted within a range of 0.18 to 0.21% in a 13% Cr martensitic stainless steel seamless pipe specified in the API-L80 grade, which is used for oil well. On the contrary, if the content of N is restricted only by "0.1% or less", then the content of N is widely selective. Usually, the N content is 0.01 to 0.05%, which is one tenth smaller than the C content. Therefore, the properties of steel were investigated on the relationship of the effective solute carbon content (C*) and ten times of the effective solute nitrogen content (N*).
  • C* effective solute carbon content
  • N* ten times of the effective solute nitrogen content
  • a delayed fracture in the impact-worked portions decreases as the content of both of C* and N* decreases.
  • the inequality (1) above is determined by applying a linear interpolation to the result.
  • An interstitial element such as C and N influences on the work hardening due to a cold working when a steel pipe is subjected to the impact work.
  • N provides pining of dislocations in order to increase the work hardening. From the experimental results, the inventors found that the work hardening and the delayed fracture due to hydrogen were suppressed remarkably when the amount of "C* + 10 N*" is restricted to 0.45 or less.
  • the delayed fracture of the impact-worked portions is influenced by the hydrogen amount and the hardness of the portions. It is necessary to reduce the effective solute carbon content (C*) and the effective solute nitrogen content (N*) and thereby reduce hardness in order to suppress the generation of cracks.
  • C* effective solute carbon content
  • N* effective solute nitrogen content
  • the amount of residual hydrogen in an as-rolled steel pipe is different from that in a heat-treated steel pipe.
  • a heat treatment temperature is substantially fixed.
  • the quenching temperature is 920 to 980 °C and the tempering temperature is 650 to 750°C.
  • Fig. 2 is a diagram showing the relationship of the amount of residual hydrogen between H1 (as-rolled) and H2 (after heat-treated) regarding the 13% Cr steel pipe used in the EXAMPLES below. For instance, at a point of the sign of ⁇ marked by "a", the amount of residual hydrogen (H1) in an as-rolled steel pipe was approximately 3 ppm, and the amount of residual hydrogen (H2) after a heat treatment was approximately 2 ppm.
  • Fig. 3 shows the result which is obtained by investigating a delayed fracture sensitivity of the impact-worked portions for an as-rolled steel pipe of a 13% Cr martensitic stainless steel having the C content of 0.19% and plotting the results on the correlation of "C* + 10N*" and H1.
  • Fig. 4 shows a result of a similar investigation and plots on the correlation of "C* + 10N*" and H2 after a heat treatment.
  • the inequalities (4) and (5) below represent the ranges of the Cr and S contents effective for suppressing an inner surface defect, which is called an internal scab.
  • the satisfaction of the inequalities (2) and (3) above makes it possible to suppress a delayed fracture in the impact-worked proportions for an as-rolled steel pipe and after a heat treatment. Nevertheless, there is a possibility that an internal scab could be generated in the process of manufacturing a steel pipe.
  • a generation of an internal scab results from a shear deformation in a circumferential direction in the process of pierce rolling with a piercing mill.
  • the shear strain causes cracks on such a portion that has a different deformation resistance in a billet as ferrite/austenite grain boundaries, segregations of sulfur and inclusions. These cracks deform and cause internal scabs in the course of rolling.
  • Cr* Cr + 4 ⁇ Si - 22 ⁇ C + 0.5 ⁇ Mn + 1.5 ⁇ Ni + 30 ⁇ N .
  • N provides a significant contribution to Cr*.
  • the Cr equivalent increases and the amount of ferrite increases, which causes an internal scab.
  • a sulfur-segregated portion also becomes an origin of generating a crack.
  • S content should be 0.010% or less, and it is preferable that S content is 0.003% or less. It is preferable that the content of oxygen (O) is 0.0060% or less in order to reduce inclusions in steel, macro-streak-flaw and the S content during steel making.
  • Fig. 5 illustrates a diagram of occurrence of internal scabs less than 2% (shown by a sign of ⁇ ) or not less than 2% (shown by a sign of ⁇ ) in the correlation of N* in abscissa and S content in ordinate.
  • This diagram leads to a recognition that restricting S content by the following inequality (5) suppresses an internal scab.
  • the criteria line is decided to be 2 % of an internal scab generation from the viewpoint of work efficiency without interrupting manufacturing. S ⁇ 0.088 N * + 0.00056.
  • the steel having the above-mentioned chemical composition and satisfying the inequalities (1), (2), (4) and (5) or inequalities (1), (3), (4) and (5) is pierce-rolled under conditions restricted by the inequality (9) with the aid of a cross roller type piercing mill.
  • feed angle and toe angle of main rollers in a piercing mill play an essential role.
  • an increase in both a feed angle and a toe angle reduces the additional shear deformation in the process of pierce rolling, and makes it possible to roll the steel without generating cracks even if it has a poor hot workability.
  • feed angle and toe angle cannot always be easily increased. In order to attain an increase in these angles, the replace of a main motor is required, and even a replace of the mill may be required. If the steel has a proper hot workability during rolling, it would be possible to choose a relatively small feed and toe angles.
  • the relationship between an index regarding a hot workability during rolling and an index suppressing an internal scab i.e. an additional shear deformation, can lead to a possible optimal manufacturing conditions of design of material of steel and conditions for pierce rolling from the viewpoint of economy in the manufacturing.
  • the present inventors researched the past experimental data to investigate the influence of feed and toe angles on the additional shear deformation, and further studied the relationship between the Cr* and the sum of "C.A. (toe angle) + F.A. (feed angle)". As a result, an explicit correlation between Cr* and "C.A. + F.A.” was found on the basis that both of feed and toe angles contribute to the same extent to an additional shear stress
  • Fig. 6 illustrates a diagram of the occurrence of both an internal scab and an external defect less than 2% (shown by ⁇ ) or not less than 2% (shown by a sign of ⁇ ) in a correlation of "C.A. + F.A.” in abscissa and Cr* in ordinate.
  • This map leads to the recognition that a boundary line of whether both an internal scab and an external defect are less than 2% (shown by ⁇ ) or not (shown by a sign of ⁇ ) can be expressed by the cubic curve.
  • a condition satisfying the following inequality (9) leads to a suppressed generation of internal scabs.
  • a manufacturing method may include a process of re-heating before finishing rolling wherein a stretch reducer is used. It is preferable, in this case, that soaking is held at a temperature of 920°C or more during re-heating.
  • a decreased soaking temperature during re-heating causes a reduced toughness of an as-rolled steel in T direction, which is perpendicular to a rolling direction, because of the incomplete recrystallization of flat grains, formed during working.
  • C and N enriched areas are generated around Nb and/or V carbides/nitrides because of the incomplete solid solution or diffusion of the carbides and/or nitrides. Then, a hardening and a brittleness take place in the areas, which cause a delayed fracture. Therefore, the lower limit of a soaking temperature during re-heating is 920°C, or more preferable 1000°C, and the upper limit of a soaking temperature is 1100°C.
  • Drop test pieces having a 250 mm length were prepared from as-rolled steel pipes.
  • a weight test element having 150 kg weight and a 90 mm curvature at its tip, was dropped from a 0.2 m height onto a test piece, which is deformed under an impact load (294J). After one week each piece was inspected as to whether or not cracks were generated. An inspection of cracks was carried out by a visual check and also by an ultrasonic test (UST). The results are listed in Tables 3 and 4.
  • Fig. 1 is a diagram showing the relationship between the generated cracks and both effective solute carbon content (C*) and effective solute nitrogen content (N*).
  • C* effective solute carbon content
  • N* effective solute nitrogen content
  • a straight line “a” implies a boundary of generating cracks.
  • the amount of residual hydrogen of an as-rolled steel pipe and the amount of the same after a heat treatment were measured using an analyzing method specified in JIS Z2614.
  • a test piece was water-quenched at the temperature of 950 °C and then tempered at 700°C.
  • the results of measurement are listed in Tables 3 and 4.
  • H ⁇ 1 - 0.003 C * + 10 ⁇ N * + 0.0016
  • H ⁇ 2 - 0.0018 C * + 10 ⁇ N * + 0.00096.
  • Table 5 shows a relationship between an internal scab generation and two parameters, Cr* and "C.A. + FA.”
  • a sign of ⁇ indicates that both an internal scab and an external scab are less than 2%
  • a sign of ⁇ indicates that either an internal scab or an external scab is not less than 2%.
  • Fig. 6 is a diagram of the results in Table 5 using the parameters, "C.A. + F.A.” and Cr*.
  • a cubic line in the diagram is expressed by the following equation (9)-1. Accordingly, the condition of suppressing an internal scab generation is to satisfy the inequality (9) above.
  • Cr * 0.00009 C . A . + F . A . 3 - 0.0035 C . A . + F . A . 2 + 0.0567 C . A . + F . A . + 8.0024.
  • Table 5 No. Cr* C.A.+F.A.
  • a 13% Cr martensitic steel seamless pipe according to the invention prevents a delayed fracture generation when it is subjected to an impact cold working during handling after manufacturing the pipe.
  • This steel pipe has an excellent corrosion resistance and is particularly available for oil well.
  • a 13% Cr martensitic seamless steel pipe can be produced without an internal scab generation according to a manufacturing method of the invention.

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EP03741248.3A 2002-07-15 2003-07-07 Martensitic stainless steel seamless pipe and a manufacturing method thereof Expired - Lifetime EP1521856B1 (en)

Applications Claiming Priority (3)

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JP2002206169 2002-07-15
JP2002206169A JP4126979B2 (ja) 2002-07-15 2002-07-15 マルテンサイト系ステンレス継目無鋼管とその製造方法
PCT/JP2003/008625 WO2004007780A1 (en) 2002-07-15 2003-07-07 Martensitic stainless steel seamless pipe and a manufacturing method thereof

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EP1521856A1 EP1521856A1 (en) 2005-04-13
EP1521856B1 true EP1521856B1 (en) 2013-08-21

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JP4273338B2 (ja) * 2004-11-26 2009-06-03 住友金属工業株式会社 マルテンサイト系ステンレス鋼管及びその製造方法
EP1867737B1 (en) * 2005-03-30 2012-03-21 Sumitomo Metal Industries, Ltd. Method for producing martensitic stainless steel
CN101394943B (zh) * 2006-03-01 2010-06-09 住友金属工业株式会社 高Cr无缝管的制造方法
CN100395479C (zh) * 2006-03-03 2008-06-18 朱国良 高性能不锈钢无缝钢管的加工工艺
JP5011770B2 (ja) * 2006-03-22 2012-08-29 住友金属工業株式会社 マルテンサイト系ステンレス鋼管の製造方法
EP2025421B1 (en) * 2006-05-26 2013-10-16 Nippon Steel & Sumitomo Metal Corporation Process for producing seamless stainless-steel pipe
JP2008221250A (ja) * 2007-03-09 2008-09-25 Sumitomo Metal Ind Ltd 継目無鋼管の製造方法
CN101532110B (zh) * 2008-09-17 2010-06-02 中国科学院金属研究所 一种消除高强韧性马氏体不锈钢中δ铁素体的方法
EP2439301B1 (en) 2009-05-07 2017-03-22 Nisshin Steel Co., Ltd. High strength stainless steel pipe
DE102012009496B4 (de) * 2012-05-14 2017-05-11 Stahlwerk Ergste Westig Gmbh Chromstahl
JP5924256B2 (ja) * 2012-06-21 2016-05-25 Ｊｆｅスチール株式会社 耐食性に優れた油井用高強度ステンレス鋼継目無管およびその製造方法
RU2530113C1 (ru) * 2013-03-05 2014-10-10 Открытое акционерное общество "Челябинский трубопрокатный завод" СПОСОБ ПРОИЗВОДСТВА БЕСШОВНЫХ ГОРЯЧЕДЕФОРМИРОВАННЫХ МЕХАНИЧЕСКИ ОБРАБОТАННЫХ ТРУБ РАЗМЕРОМ 610×36,53 мм ИЗ СТАЛИ МАРКИ 15Х5М ДЛЯ КОММУНИКАЦИЙ НЕФТЕПЕРЕРАБАТЫВАЮЩИХ ЗАВОДОВ С ПОВЫШЕННЫМИ ТРЕБОВАНИЯМИ ПО ГЕОМЕТРИЧЕСКИМ РАЗМЕРАМ
EP3705591B1 (en) * 2017-11-02 2021-03-17 Nippon Steel Corporation Piercer plug and method of manufacturing the same
CN110643894B (zh) * 2018-06-27 2021-05-14 宝山钢铁股份有限公司 具有良好的疲劳及扩孔性能的超高强热轧钢板和钢带及其制造方法
CN109536829A (zh) * 2018-11-07 2019-03-29 林州凤宝管业有限公司 一种汽车半轴套用无缝钢管及其生产方法

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EP1521856A1 (en) 2005-04-13
CN101070579A (zh) 2007-11-14
MXPA05000454A (es) 2005-03-23
WO2004007780A1 (en) 2004-01-22
CN100532617C (zh) 2009-08-26
CN1668768A (zh) 2005-09-14

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