High-strength and high-toughness perforating gun tube and manufacturing method therefor

Abstract

A high-strength and high-toughness tube for perforating gun, having a formulation of chemical elements in percentage by mass as follows: C: 0.15%-0.22%, Si: 0.1%-0.4%, Mn: 0.5%-1%, Cr: 0.3%-0.7%, Mo: 0.3%-0.7%, Nb: 0.01%-0.04%, V: 0.1%-0.2%, Ti: 0.02%-0.05%, B: 0.0015%-0.005%, Al: 0.01%-0.05%, Ca: 0.001%-0.004%, N≤0.008%, and the balance of Fe and other inevitable impurities. Accordingly, further disclosed is a method for manufacturing a high-strength and high-toughness tube for perforating gun. The high-strength and high-toughness tube for perforating gun of the present invention has high strength, good toughness and uniform circumferential strength, and is suitable for application in the field of petroleum exploration and exploitation.

Claims

1. A high-strength and high-toughness tube for a perforating gun, comprising the following chemical elements by mass percentages: C: 0.15%-0.22%, Si: 0.1%-0.4%, Mn: 0.5%-1%, Cr: 0.3%-0.7%, Mo: 0.3%-0.7%, Nb: 0.01%-0.04%, V: 0.1%-0.16%, Ti: 0.02%-0.05%, B: 0.0015%-0.005%, Al: 0.01%-0.05%, Ca: 0.001%-0.004%, N≤0.008%, and the balance of Fe and other inevitable impurities.

2. The high-strength and high-toughness tube for a perforating gun according to claim 1, wherein the tube for perforating gun further satisfies: 0<(Ti-3.4N)<0.025%.

3. The high-strength and high-toughness tube for a perforating gun according to claim 1, wherein the tube for perforating gun further satisfies: Ca/S≥1.5.

4. The high-strength and high-toughness tube for a perforating gun according to claim 1, wherein the tube for perforating gun has a microstructure of tempered sorbite.

5. The high-strength and high-toughness tube for a perforating gun according to claim 1, wherein the tube for perforating gun has a grain size level of 9 or more, and MnS inclusion level in the high-strength and high-toughness tube for perforating gun is 0.5 or less.

6. The high-strength and high-toughness tube for tube for a perforating gun according to claim 1, wherein the tube for perforating gun has a yield strength of 896˜1103 MPa, a tensile strength of 965 MPa or more, and a transverse Charpy impact energy at 0° C. of 130 J or more, and the yield strength of the high-strength and high-toughness tube for perforating gun has a range of 60 MPa or less, and the tensile strength of high-strength and high-toughness tube for perforating gun has a range of 60 MPa or less.

7. The high-strength and high-toughness tube for a perforating gun according to claim 1, wherein the tube for perforating gun has a yield strength of 965˜1173 MPa, a tensile strength of 1034 MPa or more, and a transverse Charpy impact energy at 0° C. of 130 J or more, and the yield strength of the high-strength and high-toughness tube for perforating gun has a range of 60 MPa or less, and the tensile strength of the high-strength and high-toughness tube for perforating gun has a range of 60 MPa or less.

8. The high-strength and high-toughness tube for a perforating gun according to claim 1, wherein the tube for perforating gun has a yield strength of 1069˜1276 MPa, a tensile strength of 1138 MPa or more, and a transverse Charpy impact energy at 0° C. of 120 J or more, and the yield strength of the high-strength and high-toughness tube for perforating gun has a range of 60 MPa or less, and the tensile strength of the high-strength and high-toughness tube for perforating gun has a range of 60 MPa or less.

9. A manufacturing method for the high-strength and high-toughness tube for a perforating gun according to claim 1, comprising the steps of: (1) smelting; (2) casting: casting into a round billet, an electromagnetic stirring process under a current of 600˜650 A and a frequency of 8˜20 Hz is used in the casting process to reduce dendrite segregation of tube blank, and superheating degree of liquid steel in the casting process is controlled to be less than 30° C.; (3) rolling; (4) heat treatment; and (5) hot-sizing.

10. The manufacturing method according to claim 9, wherein in the step (3), the tube blank is soaked at 1200˜1240° C., and then pierced at a temperature of 1180˜1240° C.; rolling temperature is controlled at 950˜1000° C.; the temperature of a reheating furnace is 950˜1000° C.; stretch reducing temperature is 900˜950° C.

11. The manufacturing method according to claim 9, wherein in the step (4), quenching is performed at first, wherein the quenching temperature is 880˜920° C., and holding time is 30˜60 min; tempering is then performed, wherein the tempering temperature is 550˜650° C., and holding time is 50˜80 min.

12. The manufacturing method according to claim 9, wherein in the step (5), the temperature of the hot-sizing is 500˜550° C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the microstructure of the high-strength and high-toughness tube for perforating gun of Example 5.

(2) FIG. 2 shows the microstructure of a conventional tube for perforating gun of Comparative Example 2.

(3) FIG. 3 shows the microstructure of a conventional tube for perforating gun of Comparative Example 5.

DETAILED DESCRIPTION

(4) The high-strength and high-toughness tube for perforating gun and manufacturing method thereof of the present invention will be further explained and illustrated below with reference to the accompanying drawings and specific Examples. However, the explanations and illustrations do not unduly limit the technical solutions of the present invention.

Examples 1-5 and Comparative Examples 1-5

(5) The high-strength and high-toughness tubes for perforating gun of Examples 1-5 and the conventional tubes for perforating gun of Comparative Examples 1-5 were obtained by the following steps:

(6) (1) smelting: the initial smelting is carried out in an electric furnace, wherein the mass percentage of each chemical element was controlled according to Table 1; after primary smelting, external refining, vacuum degassing and argon stirring were carried out; then, inclusion denaturation were carried out by Ca treatment to reduce the content of inclusions;

(7) (2) casting: casting into a round billet, using electromagnetic stirring process in the casting process, the current in electromagnetic stirring was 600˜650A and the frequency was 8˜20 Hz to reduce the dendrite segregation of tube blank, and the superheating degree of liquid steel in the casting process is controlled to less than 30° C.;

(8) (3) rolling: the tube blank was soaked at 1200˜1240° C., and then perforated at a temperature of 1180˜1240° C.; the rolling temperature was controlled to 950˜1000° C.; the temperature of the reheating furnace was 950˜1000° C.; the stretch reducing temperature is 900˜950° C.;

(9) (4) heat treatment: first, quenching was performed at a quenching temperature of 880˜920° C., and the holding time was 30˜60 min; then, tempering was performed at a tempering temperature of 550˜650° C., and the holding time was 50˜80 min;

(10) (5) hot-sizing: the temperature of hot-sizing was 500˜550° C.

(11) Table 1 lists the mass percentages of chemical elements of high-strength and high-toughness tubes for perforating gun of Examples 1-5 and conventional tubes for perforating gun of Comparative Examples 1-5.

(12) TABLE-US-00001 TABLE 1 (wt %, the balance is Fe and other inevitable impurities other than P and S) C Si Mn Cr Mo Nb V Ti B Al Ca P S N Ti − 3.4 * N Ca/S Example 1 0.15 0.2 0.5 0.3 0.5 0.01 0.1 0.02 0.0015 0.01 0.002 0.009 0.0012 0.004   0.0064 1.7 Example 2 0.17 0.1 0.7 0.4 0.6 0.02 0.12 0.03 0.002 0.04 0.0015 0.01 0.001 0.005   0.013 1.5 Example 3 0.19 0.3 0.9 0.5 0.7 0.01 0.14 0.04 0.003 0.05 0.002 0.01 0.003 0.006   0.0196 1.7 Example 4 0.21 0.4 1 0.6 0.3 0.01 0.16 0.05 0.004 0.03 0.0035 0.012 0.002 0.008   0.0228 1.75 Example 5 0.22 0.25 1.5 0.7 0.4 0.04 0.2 0.04 0.005 0.02 0.004 0.013 0.002 0.007   0.0162 2 Comparative 0.08 0.2 0.5 0.3 0.5 0.01 0.05 0.02 0.0015 0.01 0.002 0.009 0.0012 0.004   0.0064 1.7 Example 1 Comparative 0.28 0.1 0.7 1.2 0.6 0.02 0.12 0.03 0.002 0.04 0.0015 0.01 0.001 0.005   0.013 1.5 Example 2 Comparative 0.2 0.1 0.7 0.5 0.6 0.02 0.12 0 0 0.04 0.0015 0.01 0.001 0.005 −0.017 1.5 Example 3 Comparative 0.19 0.3 0.9 0.5 0.7 0.01 0.14 0.02 0.003 0.05 0.005 0.01 0.003 0.007 −0.0038 1.7 Example 4 Comparative 0.19 0.3 0.9 0.5 0.9 0.01 0.14 0.03 0.003 0.05 0.002 0.01 0.003 0.007   0.0062 0.7 Example 5

(13) Table 2 lists the specific process parameters of the manufacturing methods of the Examples and the Comparative Examples.

(14) TABLE-US-00002 TABLE 2 tube blank Electromagnetic Reheating soaking stirring Perforating Finishing furnace temperature current Frequency temperature temperature temperature (° C.) (A) (Hz) (° C.) (° C.) (° C.) Example 1 1220 600 8 1180 950 960 Example 2 1230 610 10 1190 960 970 Example 3 1240 620 12 1220 970 980 Example 4 1200 630 15 1230 990 965 Example 5 1210 640 18 1240 1000 1000 Comparative 1230 630 15 1220 970 980 Example 1 Comparative 1240 630 15 1230 990 965 Example 2 Comparative 1200 630 15 1240 1000 1000 Example 3 Comparative 1200 630 15 1180 960 1000 Example 4 Comparative 1220 630 15 1190 970 980 Example 5 Stretch hot- reducing Quenching Holding Tempering Holding sizing temperature temperature time temperature time temperature (° C.) (° C.) (min) (° C.) (min) (° C.) Example 1 900 880 50 550 50 500 Example 2 910 890 30 580 60 510 Example 3 920 900 60 630 60 520 Example 4 930 910 60 650 80 530 Example 5 950 920 40 610 70 550 Comparative 920 930 40 620 70 530 Example 1 Comparative 930 930 60 620 60 520 Example 2 Comparative 950 940 40 620 60 530 Example 3 Comparative 950 930 60 620 60 530 Example 4 Comparative 920 930 60 620 60 530 Example 5

(15) The performance tests were carried out using samples of high-strength and high-toughness tubes for perforating gun of Examples 1-5 and conventional tubes for perforating gun of Comparative Examples 1-5. The results obtained by the test are listed in Table 3.

(16) Table 3 lists the results obtained by the test of high-strength and high-toughness tubes for perforating gun of Examples 1-5 and conventional tubes for perforating gun of Comparative Examples 1-5.

(17) TABLE-US-00003 TABLE 3 Transverse Range of Range of impact yield tensile Yield strength Tensile strength Elongation energy, 0° C. strength strength (MPa) (MPa) (%) (J) (MPa) (MPa) Example 1 980 1040 25 145 50 40 Example 2 1040 1160 21 135 40 50 Example 3 1080 1190 19 132 50 50 Example 4 1100 1180 20 138 40 40 Example 5 1120 1200 18 128 40 50 Comparative 820 900 25 120 40 50 Example 1 Comparative 960 1100 18 70 90 80 Example 2 Comparative 950 1050 22 82 80 80 Example 3 Comparative 1000 1100 18 79 50 60 Example 4 Comparative 1100 1100 18 73 50 50 Example 5

(18) As can be seen from Table 3, the yield strength, tensile strength and transverse impact energy of the Examples of the present application are significantly higher than that of the Comparative Examples, indicating that the Examples of the present application has high strength and good toughness. In addition, the ranges of yield strength of the Examples are 60 MPa or less, and the ranges of tensile strength of the Examples are also 60 MPa or less, indicating that the Examples have uniform circumferential strength.

(19) As can be seen from Tables 1 to 3, the mass percentages of C and V of Comparative Example 1 are lower than the range of elemental masses defined by the present invention, resulting in low hardenability and low strength after heat treatment. The mass percentages of C and Cr elements in Comparative Example 2 are too high, resulting in significant banded structure segregation. Therefore, the transverse impact energy of Comparative Example 2 is significantly decreased, and the range of yield strength and the range of tensile strength are large. Comparative Example 3 did not contain B and Ti elements, resulting in a decrease in transverse impact energy, a large range of yield strength and a large range of tensile strength. In Comparative Example 4, the mass percentage of Ca is too high, resulting in the formation of coarse non-metallic inclusions, which increases the brittleness and reduces the transverse impact energy of Comparative Example 4. In addition, in Comparative Example 4, Ti-3.4*N≤0, and thus BN is easily formed after heat treatment, which is not conducive to the improvement of strength and toughness of Comparative Example 4. In Comparative Example 5, the Mo content is high and the Ca/S ratio is less than 1.5, resulting in the formation of coarse MnS inclusions and carbides of Mo in Comparative Example 5, which reduces the transverse impact toughness.

(20) FIG. 1 shows the microstructure of the high-strength and high-toughness tube for perforating gun of Example 5. As shown in FIG. 1, the microstructure of Example 5 is tempered sorbite and free of banded structure segregation, and MnS inclusions is in a level of 0.5 or less.

(21) FIG. 2 shows the microstructure of a conventional tube for perforating gun of Comparative Example 2. As shown in FIG. 2, in Comparative Example 2, the banded structure segregation is significant due to the high mass percentages of the C and Cr elements.

(22) FIG. 3 shows the microstructure of a conventional tube for perforating gun of Comparative Example 5. As shown in FIG. 3, in Comparative Example 5, coarse MnS inclusions are formed.

(23) It should be noted that the above are merely illustrative of specific Examples of the invention. It is obvious that the present invention is not limited to the above Examples, but has many similar variations. All modifications that are directly derived or associated by those skilled in the art are intended to be within the scope of the present invention.