WO2014048337A1

WO2014048337A1 - High-frequency straight welded pipe and manufacturing method thereof

Info

Publication number: WO2014048337A1
Application number: PCT/CN2013/084267
Authority: WO
Inventors: 王怡然; 沈建兰; 崔俊; 谷中莹; 吴文辉
Original assignee: 宝山钢铁股份有限公司
Priority date: 2012-09-29
Filing date: 2013-09-26
Publication date: 2014-04-03
Also published as: SA515360196B1; CN102912253B; CN102912253A; AU2013324845B2; CA2885696A1; AU2013324845A1; CA2885696C

Abstract

The present invention discloses a high-frequency straight welded pipe. The high-frequency straight welded pipe comprises the following chemical element percentages by mass: 0.042-0.056% of C, 0.18-0.22% of Si, 0.75-0.95% of Mn, 0.0064-0.015% of P, 0.0006-0.002% of S, 0.012-0.018% of Ti, 0.001-0.002% of V, 0.026-0.038% of Al, 0.080-0.13% of Ni, 0.020-0.029% of Nb, 0.125-0.135% of Cu, 0.018-0.03% of Cr, 0.004-0.008% of Mo, 0-0.0005% of B, 0.001-0.003% of Ca, and the balance of Fe and other inevitable impurities. Meanwhile, further disclosed is a manufacturing method for the high-frequency straight welded pipe.

Description

High-frequency straight seam welded pipe and manufacturing method thereof

Technical field

The present invention relates to a steel pipe and a method of manufacturing the same, and more particularly to a high frequency welded pipe and a method of manufacturing the same. Background technique

In the field of oil and gas production and transportation, high-frequency straight seam welded pipe (HFW) is widely used due to its low manufacturing cost, high dimensional accuracy and easy control of the length of the fixed length. It is mainly used for oil and gas on land and seabed. The transportation of pulp has a broad application prospect.

As global demand for oil and natural gas continues to grow, the conditions for the exploitation of oil and gas wells are deteriorating and complex. Due to the development of some oil and gas fields with high levels of 11 and S and severe corrosive environments, it is urgent to develop and produce steel pipes for oil and gas transportation pipes under such acidic working conditions. At present, there are hundreds of high-frequency straight seam welded pipe (HFW) units in China, but most manufacturers can only rely on large steel mills to supply coil materials, mainly producing conventional steel grade steel pipes. There is no corresponding manufacturer in China for high-grade steel pipe with excellent performance against HIC (hydrogen induced crack). For the L360MCS steel grade high-frequency straight seam welded pipe with anti-HIC performance and its manufacturing process, there is still a gap in China. Summary of the invention

The object of the present invention is to provide a high-frequency straight seam welded pipe which has good anti-HIC performance and can achieve L360MCS steel grade performance, has high yield strength, tensile strength and impact. Toughness and weldability.

In order to achieve the above object, the present invention provides a high frequency straight seam welded pipe having a chemical element mass percentage of:

C: 0·042~0·056%;

Si: 0·18~0·22%;

Μη: 0·75~0·95%;

Ρ: 0·0064~0·015%; S: 0·0006 0·002%;

Ti: 0·012 0·018%;

V 0.001 0.002%;

Al: 0·026 0·038%;

Ni: 0·080 0·13%;

Nb: 0·020 0·029%;

Cu: 0.125 0.135%;

Cr: 0·018 0·03%;

Mo: 0.004—0.008%

B: 0 05%;

Ca: 0.001 0·003%;

The balance is Fe and other unavoidable impurities.

The composition principle of the main chemical elements in the high-frequency straight seam welded pipe according to the present invention is as follows: C: C is the main solid solution strengthening element of pipeline steel. The researchers have shown through a large number of experiments that the sensitivity of hydrogen induced cracking (HIC) of strip steel increases with the increase of C content in strip, so the appropriate control of C content is acceptable and does not affect the lower limit of strip strength. The scope is necessary. The content of C is appropriately lowered by this component, and is reduced from about 0.07 wt% to 0.056 wt% or less. Therefore, in the technical solution of the present invention, C is controlled to 0.042 0.056 wt%.

S: In low-sulfur steel, the crack length ratio decreases and MnS appears on the fracture fracture, which indicates that the reduction of N S in the strip can effectively control crack formation. However, if the content of S is lowered to a very low level, the occurrence of cracks in the strip steel cannot be avoided, so it is not necessary to blindly pursue the reduction of the S content. The inventors have found through a large number of experiments that controlling the mass percentage of S to 0.0006 0.002% can not only meet the corrosion resistance requirements but also prevent the occurrence of cracks in the steel strip.

Ca: Ca treatment has an important influence on the resistance to hydrogen induced cracking (HIC) of the strip. In the present invention, by adding appropriate Ca to the composition, CaS precipitated at the final solidification position is changed into spherical inclusions after rolling, thereby improving the hydrogen-induced cracking (HIC) performance of the steel strip. However, the content control of Ca has a correlation with the S content. Therefore, the technical solution of the present invention controls the content of Ca to 0.001 0.003 wt%.

Cu: Of the many alloying elements, only copper is advantageous against hydrogen induced cracking (HIC) properties. Adding a certain amount of copper to the pipeline steel, the hydrogen induced crack sensitivity is significantly reduced, mainly copper promotes blunt The formation of the film reduces the intrusion of hydrogen and hinders the formation of hydrogen induced cracks. In the technical solution of the present invention, the resistance to hydrogen induced cracking (HIC) is improved by adding a certain amount of copper. Therefore, the Cu content is controlled to be 0.125 to 0.135 wt%.

Mn: The effect of Mn on the hydrogen induced cracking resistance of pipeline steel is mainly reflected in the influence of Mn on the phase transformation process of strip steel. When the Mn content exceeds 1.0 wt%, the sensitivity of hydrogen induced cracking (HIC) increases. Therefore, in the technical solution of the present invention, the Mn content is set to 0.75 to 0.95 wt%.

Correspondingly, the present invention also provides a method for manufacturing the above-mentioned high-frequency straight seam welded pipe, comprising the following steps: in the waste pipe forming step, controlling the amount of extrusion to be 2 to 3% of the outer diameter of the welded pipe;

In the welding step, the welding speed is controlled to be 18~20m/min _;

After the post-weld heat treatment, the weld is subjected to normalizing heat treatment at a temperature of 930 to 970 ° C. After normalizing, the weld is air-cooled to below 380 ° C, and then water-cooled to lower the temperature of the weld to below 80 ° C.

Further, in the waste pipe forming step of the method for producing a high-frequency straight seam welded pipe of the present invention, the opening angle is controlled to be 3 to 4.2°.

In the technical solution of the present invention, the amount of extrusion before and after welding is controlled to be 2 to 3% of the outer diameter of the welded pipe, and the amount of extrusion refers to the difference between the circumference of the waste pipe before extrusion and the circumference after extrusion. In the molten state, the molten pool at the weld is exposed to the air, and the oxidation reaction is prone to occur. The oxidation reaction product is closely related to the chemical composition of the strip. Therefore, it is necessary to use a large amount of extrusion to extrude the produced high melting point product onto the surface of the strip weld and remove it by deburring. However, the amount of extrusion below 2% is prone to defects such as cold welding, which makes it impossible to remove the inclusions in the strip from the surface of the weld, thereby affecting the strip to set the welding speed to 18 to 20 m/min. The reason is that the welding speed is usually inversely proportional to the welding power, and the faster welding speed easily offsets the high welding power and the large amount of extrusion, which is easy to discharge the inclusions, resulting in a decrease in the discharge inclusion effect. Therefore, for the present technical solution, the inventors controlled the welding speed to 18 to 20 m/min.

The manufacturing method of the high-frequency straight seam welded pipe according to the present invention is based on the high-frequency straight seam induction welding (HFW) manufacturing method, and the high-frequency welding forming and welding parameters are set by appropriately adjusting the extrusion amount and the molding process. Control the subsequent heat treatment technical parameters to produce high-frequency straight seam welded pipes that meet HIC resistance, tensile properties, impact toughness and microstructure requirements.

Compared with the prior art, the high-frequency straight seam welded pipe of the invention has good anti-HIC performance, and achieves L360MCS steel grade performance, has high yield strength, tensile strength, impact toughness. Sex and welding performance, suitable as a conveying pipe for harsh working environments with high H or S content or acid corrosion. detailed description

Example 1-6

The high frequency straight seam welded pipe of the present invention is manufactured according to the following steps:

After the unwinding, the head and the tail of the coil are cut off to form a flush cut 3° in the transverse direction of the coil, and the tail of the previous coil and the head of the next coil are rolled by carbon dioxide gas shielded welding. Welded together; high-frequency straight seam welded pipe is produced by steel strip, and the edge width of the strip and the perpendicularity of the edge of the board are precisely controlled by the edge milling method; the strip forming method is used to form the strip into a waste pipe, and the pressing amount is controlled as a welded pipe. 2~3% of the outer diameter; control opening angle is 3~4.2°; when welding, the welding speed is controlled to 18~20m/min; after welding, the weld is subjected to normalizing heat treatment, and the normalizing heat treatment temperature is 930~970° C. After normalizing, the weld is air cooled to below 380 °C, then water cooled to reduce the temperature of the weld to below 80 °C. The high-frequency straight seam welded pipe obtained by the above process has a wall thickness of 6.4 mm to 9.5 mm and a pipe diameter of 219.7 mm to 406.4 mm.

Table 1 shows the chemical distribution ratios of the high-frequency straight seam welded pipes in Examples 1-6.

Table 1 (The balance is Fe and other unavoidable impurities, wt%)

Table 2 shows the detailed process parameters for manufacturing high frequency straight seam welded pipes in Examples 1-6. Table 2

Table 3 shows the performance parameters of each of the high frequency straight seam welded pipes in Examples 1-6.

table 3

It can be seen from Table 3 that the high-frequency straight seam welded pipe of the present invention has good mechanical properties and has anti-HIC performance, as follows: welded pipe body yield strength 399Mpa, tensile strength 505^^&, elongation 24%, welded pipe The tensile strength of the weld is 475Mpa, which indicates that the high-frequency straight seam welded pipe meets the high strength requirements and has high tensile strength. The impact toughness of the welded pipe body is the minimum value of the Charpy impact work. 119J, mean value 127J, impact toughness of welded pipe weld Charpy impact value of single value 139J, average value of 145J, indicating that the high frequency straight seam welded pipe has better toughness and welding performance; as evaluation of strip material Three parameters of the resistance to hydrogen induced cracking (HIC) performance: crack sensitivity (CSR:), crack length ratio (CLR) and crack thickness ratio (CTR), all shown in Table 3 are 0%, indicating The high frequency straight seam welded pipe has good resistance to hydrogen induced cracking (HIC). It is to be noted that the above is only the specific embodiment of the present invention, and it is obvious that the present invention is not limited to the above embodiment, and there are many similar variations. All modifications that are directly derived or conceived by those skilled in the art from the disclosure of the present invention should fall within the scope of the present invention.

Claims

Claim

A high-frequency straight seam welded pipe characterized in that the chemical element mass percentage thereof is:

C: 0·042 0·056%;

Si: 0·18 0·22%;

Μη: 0·75 0·95%;

Ρ: 0·0064 0·015%;

S: 0·0006 0·002%;

Ti: 0·012 0·018%;

V 0.001 0.002%;

Α1: 0·026 0·038%;

Ni: 0·080 0·13%;

Nb: 0·020 0·029%;

Cu: 0.125 0.135%;

Cr: 0·018 0·03%;

Μο: 0.004—0.008%

Β: 0 05%;

Ca: 0.001 0·003%;

The balance is Fe and other unavoidable impurities.

2. The method of manufacturing a high frequency straight seam welded pipe according to claim 1, wherein:

In the waste pipe forming step, the amount of extrusion is controlled to be 2 3% of the outer diameter of the welded pipe.

In the welding step, the welding speed is controlled to be 18 20 m/min _;

After the post-weld heat treatment, the weld is subjected to normalizing heat treatment at a temperature of 930 970 °C. After normalizing, the weld is air-cooled to below 380 °C, and then water-cooled to reduce the temperature of the weld to below 80 °C.

3. The method of manufacturing a high-frequency straight seam welded pipe according to claim 2, wherein in the waste pipe forming step, the control opening angle is 3 4.2°.