SEAMLESS STEEL TUBE RESISTANT TO CARBON DIOXIDE CORROSION AND MANUFACTURING METHOD THEREFOR

Abstract

Disclosed in the present application is a high-strength seamless steel tube resistant to carbon dioxide corrosion. In addition to containing Fe and inevitable impurities, the seamless steel tube comprises the following chemical elements in mass percentage: C: 0.05-0.18%, Si: 0.15-0.40%, Mn: 0.25-0.50%, Cr: 4.0-6.0%, Mo: 0.08-0.35%, Al: 0.020-0.055%, Ca: 0.001-0.004%; and one or more elements selected from Ti, Nb, V, Ce, and La, wherein 0.003%?Ti+Nb+V+Ce+La?0.20%. Also disclosed in the present application is a manufacturing method for the seamless steel tube. The method comprises the following steps: (1) manufacturing a tube billet; (2) subjecting the tube billet to heating, perforating, hot rolling, and sizing to obtain a hot-rolled tube; and (3) subjecting the hot-rolled tube to a quenching and tempering heat treatment: quenching within a temperature range of 860-940? C. for 15-120 min, and then tempering within a temperature range of 520-620? C. for 30-150 min.

Claims

1. A seamless steel tube resistant to corrosion by carbon dioxide, comprising the following chemical elements in mass percentage, in addition to containing Fe and inevitable impurities: C: 0.05-0.18%, Si: 0.15-0.40%, Mn: 0.25-0.50%, Cr: 4.0-6.0%, Mo: 0.08-0.35%, Al: 0.020-0.055%, Ca: 0.001-0.004%; and one or more selected from Ti, Nb, V, Ce, and La, wherein 0.003%?Ti+Nb+V+Ce+La?0.20%.

2. The seamless steel tube according to claim 1, wherein the seamless steel tube consists of the following chemical elements in mass percentage: C: 0.05-0.18%, Si: 0.15-0.40%, Mn: 0.25-0.50%, Cr: 4.0-6.0%, Mo: 0.08-0.35%, Al: 0.020-0.055%, Ca: 0.001-0.004%; and one or more selected from Ti, Nb, V, Ce, and La, wherein 0.003%?Ti+Nb+V+Ce+La?0.20%, and the balance of Fe and inevitable impurities.

3. The seamless steel tube according to claim 1, wherein the content of the chemical elements in the seamless steel tube further satisfy at least one of the following: C: 0.09-0.15%, Si: 0.2-0.35%, Mn: 0.3-0.45%, Cr: 4.5-5.5%, Mo: 0.1-0.25%, Al: 0.025-0.045%, Ca: 0.0015-0.003%, and 0.005%?Ti+Nb+V+Ce+La?0.15%.

4. The seamless steel tube according to claim 1, wherein among the inevitable impurities, P?0.015%, S?0.008%, N?0.006%, and O?0.0035%.

5. The seamless steel tube according to claim 4, wherein among the inevitable impurities, P?0.012%, S?0.005%, N?0.0045%, and O?0.002%.

6. The seamless steel tube according to claim 1, having a tempered sorbite structure.

7. The seamless steel tube according to claim 1, wherein the properties of the seamless steel tube satisfy at least one of the following: yield strength Rp0.2?550 MPa, tensile strength Rm?670 MPa, elongation A50?15%, and impact property KV8?60 J; under the dynamic corrosion environment conditions of 60-90? C., 0.5 MPa CO.sub.2, 50,000 ppm Cl.sup.?, and 1 m/s, a weight loss corrosion rate is less than 0.08 mm/d, and a pitting corrosion rate is less than 0.2 mm/d.

8. A manufacturing method for the seamless steel tube resistant to carbon dioxide corrosion according to claim 1, wherein the manufacturing method excludes a spheroidizing annealing step and comprises the following steps: (1) manufacturing a tube billet; (2) subjecting the tube billet to heating, perforating, hot rolling, and sizing to obtain a hot-rolled tube; and (3) subjecting the hot-rolled tube to quenching and tempering heat treatment: quenching the hot-rolled tube in a temperature range of 860-940? C. and holding for 15-120 min, followed by tempering the quenching tube in a temperature range of 520-620? C. and holding for 30-150 min.

9. The manufacturing method according to claim 8, wherein in the heating step of step (2), the tube billet is heated at 1180-1280? C. and held for 120-350 min.

10. The manufacturing method according to claim 8 or 9, wherein in step (2), perforating, hot rolling, and sizing are performed in a temperature range of 1160-1260? C.

11. The seamless steel tube according to claim 2, wherein the content of the chemical elements in the seamless steel tube further satisfy at least one of the following: C: 0.09-0.15%, Si: 0.2-0.35%, Mn: 0.3-0.45%, Cr: 4.5-5.5%, Mo: 0.1-0.25%, Al: 0.025-0.045%, Ca: 0.0015-0.003%, and 0.005%?Ti+Nb+V+Ce+La?0.15%.

12. The seamless steel tube according to claim 2, wherein among the inevitable impurities, P?0.015%, S?0.008%, N?0.006%, and O?0.0035%.

13. The seamless steel tube according to claim 2, having a tempered sorbite structure.

14. The seamless steel tube according to claim 2, wherein the properties of the seamless steel tube satisfy at least one of the following: yield strength Rp0.2?550 MPa, tensile strength Rm?670 MPa, elongation A50?15%, and impact property KV8?60 J; under the dynamic corrosion environment conditions of 60-90? C., 0.5 MPa CO.sub.2, 50,000 ppm Cl.sup.?, and 1 m/s, a weight loss corrosion rate is less than 0.08 mm/d, and a pitting corrosion rate is less than 0.2 mm/d.

15. The manufacturing method according to claim 9, wherein in step (2), perforating, hot rolling, and sizing are performed in a temperature range of 1160-1260? C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG. 1 is a photograph of the microstructure of the seamless steel tube in Example 1 under an optical microscope.

DETAILED DESCRIPTION

[0065] Hereinafter, the seamless steel tube and the manufacturing method therefor according to the present disclosure will be further explained and described with reference to the specific embodiments and the accompanying drawings. However, this explanation and description are not intended to unduly limit the technical solution of the present disclosure.

Examples 1-15 and Comparative Examples 1-5

[0066] Seamless steel tubes in Examples 1-15 and Comparative Examples 1-2 and Comparative Examples 4-5 are all produced using the following steps: [0067] (1) Performing smelting and refining using electric furnace or converter smelting according to the chemical composition shown in Table 1, and then casting metal into tube billet. [0068] (2) Subjecting the tube billet to heating, perforating, hot rolling, and sizing to obtain a hot-rolled tube: heating the tube billet at 1180-1280? C. and holding for 120-350 min, and then performing high-temperature deformation such as high-temperature perforating, hot rolling, and sizing in the range of 1160-1260? C. to produce a hot-rolled tube with required sizes. [0069] (3) Subjecting the hot-rolled tube to quenching and tempering heat treatment: the hot-rolled tube is cut to the required dimensions. Then, it undergoes quenching within the temperature range of 860-940? C. with a holding time of 15-120 min (Comparative Example 3), followed by tempering within the temperature range of 520-620? C. with a holding time of 30-150 min. [0070] (4) The seamless steel tube in Comparative Example 3 is prepared using the same method as described above, with the only difference being quenching and holding at 946? C.

[0071] It should be noted that in the present disclosure, the chemical composition design and relevant manufacturing processes for the seamless steel tubes in Examples 1-15 meet the design specification requirements of the present disclosure. However, for the seamless steel tubes in Comparative Examples 1-5, there are parameters that do not meet the design requirements of the present disclosure in the chemical composition design and related manufacturing processes.

[0072] Table 1 lists the mass percentages of chemical elements in the seamless steel tubes in Examples 1-15 and the seamless steel tubes in Comparative Examples 1-5.

TABLE-US-00001 TABLE 1 (wt %, the balance being Fe and other inevitable impurities other than P, S, N, and O) Serial Ti + Nb + Number C Si Mn P S Cr Mo N O Al Ca V + Ce + La Remark Example 1 0.065 0.34 0.27 0.012 0.0037 4.26 0.32 0.002 0.0011 0.030 0.0020 0.139 Ti + V Example 2 0.104 0.21 0.38 0.012 0.0065 5.08 0.12 0.005 0.0019 0.041 0.0013 0.121 V + Ce Example 3 0.091 0.19 0.42 0.009 0.0036 5.12 0.20 0.006 0.0009 0.033 0.0034 0.094 Ti + Ce + La Example 4 0.072 0.29 0.45 0.002 0.0047 4.14 0.23 0.004 0.0023 0.031 0.0018 0.178 Ti + V + Ce Example 5 0.093 0.16 0.30 0.006 0.0052 4.86 0.32 0.001 0.0022 0.030 0.0028 0.092 Nb + V Example 6 0.092 0.38 0.26 0.006 0.0046 5.33 0.19 0.002 0.0011 0.035 0.0019 0.143 Ti + Nb + V Example 7 0.050 0.29 0.42 0.008 0.0052 4.73 0.12 0.001 0.0018 0.040 0.0014 0.199 V Example 8 0.180 0.27 0.49 0.007 0.0003 4.28 0.34 0.003 0.0026 0.051 0.0029 0.175 Nb + Ce Example 9 0.150 0.38 0.39 0.013 0.0058 5.68 0.23 0.005 0.0021 0.022 0.0029 0.095 Nb + La + Ce Example 10 0.127 0.17 0.37 0.009 0.0043 5.35 0.34 0.002 0.0016 0.035 0.0036 0.041 Ti + La Example 11 0.081 0.15 0.50 0.001 0.0040 5.89 0.25 0.004 0.0026 0.043 0.0036 0.035 Ti Example 12 0.152 0.33 0.46 0.007 0.0018 4.35 0.22 0.005 0.0031 0.039 0.0040 0.103 Ti + La Example 13 0.180 0.30 0.33 0.009 0.0079 5.43 0.13 0.002 0.0030 0.021 0.0025 0.078 Na + La Example 14 0.174 0.31 0.30 0.015 0.0019 5.14 0.33 0.003 0.0034 0.030 0.0037 0.153 V + La Example 15 0.103 0.17 0.40 0.010 0.0029 4.51 0.13 0.001 0.0025 0.051 0.0015 0.134 Ti + Nb Comparative 0.277 0.22 0.32 0.005 0.0011 2.58 0.35 0.005 0.0015 0.039 0.0022 Example 1 Comparative 0.267 0.17 0.40 0.004 0.0065 2.05 0.20 0.005 0.0036 0.042 0.0020 Example 2 Comparative 0.207 0.36 0.37 0.014 0.0019 2.00 0.37 0.003 0.0032 0.034 0.0038 Example 3 Comparative 0.321 0.26 0.38 0.003 0.0011 3.18 0.39 0.002 0.0019 0.023 0.0030 Example 4 Comparative 0.222 0.27 0.34 0.005 0.0030 3.05 0.32 0.005 0.0025 0.025 0.0032 Example 5

[0073] Table 2 lists specific process parameters of the seamless steel tubes in Examples 1-15 and Comparative Examples 1-5.

TABLE-US-00002 TABLE 2 Step (2) Perforating, Tube billet hot rolling, Step (3) heating Tube billet and sizing Quenching Quenching Tempering Tempering Serial temperature holding temperature temperature holding time temperature holding time Number (? C.) time (min) (? C.) (? C.) (min) (? C.) (min) Example 1 1249 143 1222 863 79 605 69 Example 2 1280 228 1260 936 77 618 131 Example 3 1215 347 1202 939 62 558 70 Example 4 1244 308 1234 898 67 541 57 Example 5 1250 245 1205 927 67 590 63 Example 6 1280 346 1237 940 95 526 59 Example 7 1279 287 1237 907 16 604 100 Example 8 1206 152 1197 904 95 530 41 Example 9 1234 138 1220 919 93 579 146 Example 10 1214 217 1184 894 98 559 102 Example 11 1278 155 1175 864 100 537 143 Example 12 1235 165 1173 932 114 619 94 Example 13 1233 221 1217 870 16 596 118 Example 14 1245 279 1215 923 87 608 36 Example 15 1267 148 1233 863 62 585 70 Comparative 1227 161 1189 893 45 611 87 Example 1 Comparative 1275 299 1215 910 45 614 107 Example 2 Comparative 1201 347 1188 946 67 597 133 Example 3 Comparative 1185 213 1165 906 108 601 139 Example 4 Comparative 1242 147 1198 870 85 584 112 Example 5

[0074] The seamless steel tubes in Examples 1-15 and Comparative Examples 1-5 produced after quenching and tempering heat treatment were separately sampled and subjected to various property tests to measure the mechanical properties of the seamless steel tubes in Examples 1-15 and Comparative Examples 1-5. The test results obtained are listed in Table 3.

[0075] The relevant methods for testing mechanical properties are as follows: [0076] Tensile test: The test steel pipes were subjected to a tensile test according to GB/T 228.1-2010 Metallic Materials-Tensile Testing-Part 1: Method of tensile test at room temperature to evaluate the tensile properties of the steel tubes in each example and comparative example.

[0077] Charpy V-notch impact test: the test steel tubes were subjected to an impact test according to GB/T229-2020 Metallic Materials-Charpy pendulum impact test method to evaluate the impact properties of the steel tubes in each example and comparative example.

[0078] Table 3 lists the mechanical property test results of the seamless steel tubes in Examples 1-15 and Comparative Examples 1-5.

TABLE-US-00003 TABLE 3 Serial Rp0.2 Rm A.sub.50 KV8 Number (MPa) (MPa) (%) (0? C.), J Example 1 656 733 21 198 Example 2 585 679 24 214 Example 3 851 931 18 115 Example 4 856 974 15 124 Example 5 792 975 20 189 Example 6 936 1068 15 61 Example 7 756 841 17 195 Example 8 878 1132 15 97 Example 9 806 1072 15 74 Example 10 850 971 17 158 Example 11 870 943 18 177 Example 12 936 1132 16 62 Example 13 793 978 19 121 Example 14 622 724 20 184 Example 15 793 902 18 163 Comparative 622 731 21 120 Example 1 Comparative 756 841 20 115 Example 2 Comparative 936 1128 15 58 Example 3 Comparative 832 896 15 97 Example 4 Comparative 1020 1159 14 35 Example 5

[0079] Accordingly, after the mechanical properties of the above-described seamless steel tubes in Examples 1-15 and Comparative Examples 1-5 were tested, the corrosion resistance, particularly resistance to CO.sub.2 corrosion, of the seamless steel tubes in each example and comparative example was further tested. This involves sampling from the seamless steel tubes in Examples 1-15 and Comparative Examples 1-5 and conducting corrosion tests. The samples from Examples 1-15 and Comparative Examples 1-5 were subjected to corrosion tests in an autoclave system under the dynamic corrosion environment conditions of 60-90? C., 0.5 MPa CO.sub.2, 50,000 ppm Cl.sup.?, and 1 m/s to obtain the weight loss corrosion rate and the pitting corrosion rate of Examples 1-15 and Comparative Examples 1-5. The test results of the relevant corrosion tests are listed in Table 4 below.

[0080] Table 4 lists the results of the CO.sub.2 corrosion resistance test of the seamless steel tubes in Examples 1-15 and the seamless steel tubes in Comparative Examples 1-5.

TABLE-US-00004 TABLE 4 Weight loss Pitting corrosion rate corrosion rate Serial Number (mm/d) (mm/d) Example 1 0.072 0.142 Example 2 0.052 0 Example 3 0.042 0 Example 4 0.079 0.133 Example 5 0.039 0 Example 6 0.038 0 Example 7 0.041 0 Example 8 0.062 0.131 Example 9 0.034 0 Example 10 0.043 0 Example 11 0.023 0 Example 12 0.061 0.121 Example 13 0.032 0 Example 14 0.059 0.117 Example 15 0.066 0.152 Comparative Example 1 0.165 0.266 Comparative Example 2 0.234 0.298 Comparative Example 3 0.261 0.377 Comparative Example 4 0.136 0.272 Comparative Example 5 0.169 0.293

[0081] It can be seen from Table 3 and Table 4 that the seamless steel tubes in Examples 1-15 of the present disclosure have not only excellent mechanical properties but also good resistance to CO.sub.2 corrosion. The yield strength of the seamless steel tubes in Examples 1-15 is between 585 MPa and 936 MPa, the tensile strength is between 679 MPa and 1132 MPa, the elongation A50 is greater than or equal to 15%, and the impact property KV8 is between 61 J and 214 J. Accordingly, the seamless steel tubes in each example has a weight loss corrosion rate of less than 0.079 mm/d and a pitting corrosion rate of less than 0.152 mm/d, under the dynamic corrosion environment conditions of 60-90? C., 0.5 MPa CO.sub.2, 50,000 ppm Cl.sup.?, and 1 m/s.

[0082] In contrast to the seamless steel tubes in Examples 1-15, the seamless steel tubes in Comparative Examples 1-5 show significant fluctuations in mechanical properties, and their the weight loss corrosion rate (at least 0.136 mm/d) and the pitting corrosion rate (at least 0.266 mm/d) are higher than those of Examples 1-15, indicating poorer resistance to CO.sub.2 corrosion for the seamless steel tubes in Comparative Examples 1-5.

[0083] FIG. 1 is a photograph of the microstructure of the high-strength seamless steel tube in Example 1 under an optical microscope.

[0084] As shown in FIG. 1, the microstructure of the high-strength seamless steel tube in Example 1 is a tempered sorbite structure.

[0085] In conclusion, it can be seen that the seamless steel tube resistant to carbon dioxide corrosion can be obtained by reasonable chemical composition design preferably combined with optimized manufacturing processes. The seamless steel tube has high strength, good processability, and resistance to carbon dioxide corrosion, making it suitable for applications in oil and gas development and helping prevent perforation failures. It holds significant promise and practical value.

[0086] Furthermore, the combinations of technical features described herein are not limited to the combinations specified in the claims or the specific embodiments herein. All technical features described herein may be freely combined or combined in any way unless contradicted by each other.

[0087] It should also be noted that only specific embodiments of the present disclosure have been illustrated above. It is obvious that the present disclosure is not limited to the above embodiments, and there may be various similar variations. All variations that may be derived directly or conceived by those skilled in the art from the present disclosure of the present disclosure are intended to fall within the scope of the present disclosure.