High Strength, High-Temperature Corrosion Resistant Martensitic Stainless Steel and Manufacturing Method Therefor

Abstract

Disclosed is a high strength, high-temperature corrosion resistant martensitic stainless steel characterized by comprising the following chemical elements in percentages by mass: 0<C≤0.05%, 0.1-0.2% of Si, 0.20-1.0% of Mn, 11.0-14.0% of Cr, 4.0-6.0% of Ni, 1.5-2.5% of Mo, 0.001%-0.10% of N, 0.03-0.2% of V, 0.01-0.1% of Nb, 0.01-0.04% of Al, and the balance being Fe and inevitable impurities. In addition, also disclosed are tubing and casing manufactured from the above-mentioned high strength, high-temperature corrosion resistant martensitic stainless steel, and a method for manufacturing the tubing and the casing. The high strength, high-temperature corrosion resistant martensitic stainless steel of the present disclosure has an excellent high temperature corrosion resistance to carbon dioxide and chloride ions, as well as excellent low-temperature impact toughness and a high-temperature strength degradation resistance.

Claims

1. A high strength, high-temperature corrosion resistant martensitic stainless steel, comprising the following chemical elements in percentages by mass: 0<C≤0.05%, 0.1-0.2% of Si, 0.20-1.0% of Mn, 11.0-14.0% of Cr, 4.0-6.0% of Ni, 1.5-2.5% of Mo, 0.001%-0.10% of N, 0.03-0.2% of V, 0.01-0.1% of Nb, and 0.01-0.04% of Al.

2. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 1, comprising the following chemical elements in percentages by mass: 0<C≤0.05%, 0.1-0.2% of Si, 0.20-1.0% of Mn, 11.0-14.0% of Cr, 4.0-6.0% of Ni, 1.5-2.5% of Mo, 0.001%-0.10% of N, 0.03-0.2% of V, 0.01-0.1% of Nb, 0.01-0.04% of Al, and the balance being Fe and inevitable impurity elements.

3. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 1, wherein the content, in percentage by mass, of the chemical elements satisfies: (V+Nb):(C+N)=2:1-8:1.

4. The high strength, high temperature corrosion resistant martensitic stainless steel of claim 1, further comprising at least one of Ti, Zr and Re, wherein the content, in percentage by mass, of any one of Ti, Zr and Re is 0.2% or less; and Ti+Zr+Re≤0.3%.

5. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 2, wherein the inevitable impurity elements comprise at least S, P and O, wherein the content, in percentage by mass, of P, S and O satisfies at least one of: P≤0.03%, S≤0.01%, and O≤0.004%.

6. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 1, wherein the content, in percentage by mass, of the chemical elements satisfies at least one of: 0.003-0.05% of C; 0.20-0.5% of Mn; 11.5-13.5% of Cr; 4.5-5.5% of Ni; and 1.8-2.3% of Mo.

7. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 1, wherein the stainless steel has at least one of the following properties: a yield strength greater than or equal to 862 MPa at room temperature; a yield strength greater than or equal to 800 MPa at 180° C.; an impact energy at −20° C. greater than or equal to 140 J; and a uniform corrosion rate smaller than or equal to 0.125 mm/a in an environment containing CO.sub.2 and high Cl.sup.− concentration at 180° C.

8. Tubing and casing manufactured from the high strength, high-temperature corrosion resistant martensitic stainless steel of claim 1.

9. A method for manufacturing the tubing and the casing of claim 8, comprising the steps of: (1) manufacturing a pipe blank; (2) manufacturing a seamless pipe from the pipe blank, and then cooling the seamless pipe to room temperature; (3) quenching by heating the seamless pipe to a temperature of Ac3 to 1050° C., and performing heat preservation for t×(0.5-3) min; and then cooling the seamless pipe at a cooling rate of 2-40° C./s to a temperature of T1, and performing heat preservation for t×(0.5-1.5) min, wherein T1=Ms−80° C., wherein Ms is a temperature at which martensite transformation starts; (4) first tempering by heating the seamless pipe to a temperature of T2 for tempering treatment and performing heat preservation for t×(3-7) min, then cooling the seamless pipe to 100° C. or less at a cooling rate of 5-30° C./s, wherein T2 ranges from 500° C. to Ac3; and (5) second tempering by heating the seamless pipe to a temperature of T3 for second tempering treatment and performing heat preservation for t×(3-7) min, then cooling the seamless pipe to 100° C. or less at a cooling rate of 5-30° C./s, wherein T3=T2−40° C.; wherein t denotes a wall thickness in mm.

10. The method for manufacturing the tubing and the casing of claim 9, wherein in the step (3), heating the seamless pipe to a temperature of Ac3 to 1000° C.

11. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 2, wherein the content, in percentage by mass, of the chemical elements satisfies: (V+Nb):(C+N)=2:1-8:1.

12. The high strength, high temperature corrosion resistant martensitic stainless steel of claim 2, further comprising at least one of Ti, Zr and Re, wherein the content, in percentage by mass, of any one of Ti, Zr and Re is 0.2% or less; and Ti+Zr+Re≤0.3%.

13. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 2, wherein the content, in percentage by mass, of the chemical elements satisfies at least one of: 0.003-0.05% of C; 0.20-0.5% of Mn; 11.5-13.5% of Cr; 4.5-5.5% of Ni; and 1.8-2.3% of Mo.

14. The high strength, high-temperature corrosion resistant martensitic stainless steel of claim 2, wherein the stainless steel has at least one of the following properties: a yield strength greater than or equal to 862 MPa at room temperature; a yield strength greater than or equal to 800 MPa at 180° C.; an impact energy at −20° C. greater than or equal to 140 J; and a uniform corrosion rate smaller than or equal to 0.125 mm/a in an environment containing CO.sub.2 and high Cl.sup.− concentration at 180° C.

Description

DETAILED DESCRIPTION

[0060] The high strength, high-temperature corrosion resistant martensitic stainless steel and the manufacturing method therefor according to the present disclosure will be further explained and illustrated below in connection with the specific examples, which, however, do not unduly limit the technical solution of the present invention.

Examples 1-15 and Comparative Examples 1-7

[0061] Table 1 lists the mass percentage of chemical elements in high strength, high-temperature corrosion resistant martensitic stainless steel of Examples 1-15 and stainless steel of Comparative Examples 1-7.

TABLE-US-00001 TABLE 1 (%, the balance is Fe and other inevitable impurities other than P, S and O) Chemical element (V + Nb):(C + Grade C Si Mn Cr Ni Mo N V Nb Al P S O Ti Zr Re N) Example 1 A1 0.038 0.17 0.42 13.61 5.29 1.81 0.044 0.095 0.077 0.03 0.002 0.003 0.002 — 0.09 — 2.1 Example 2 A2 0.002 0.19 0.88 13.88 4.25 2.46 0.087 0.188 0.082 0.03 0.008 0.006 0.001 0.15 — — 3.0 Example 3 A3 0.014 0.16 0.79 12.65 5.59 2.26 0.056 0.047 0.091 0.02 0.026 0.008 0.001 — — 0.13 2.0 Example 4 A4 0.021 0.19 0.49 12.32 5.18 1.97 0.080 0.171 0.086 0.03 0.021 0.001 0.002 — — 0.18 2.5 Example 5 A5 0.044 0.18 0.61 13.47 4.52 1.75 0.028 0.187 0.066 0.04 0.011 0.005 0.003 — — 0.18 3.5 Example 6 A6 0.004 0.11 0.52 11.88 4.01 2.34 0.020 0.031 0.068 0.02 0.015 0.003 0.002 — 0.06 — 4.1 Example 7 A7 0.008 0.16 0.38 11.77 4.70 1.56 0.081 0.165 0.042 0.02 0.027 0.009 0.003 0.19 — — 2.3 Example 8 A8 0.010 0.16 0.37 13.72 4.89 2.20 0.025 0.048 0.077 0.03 0.011 0.001 0.003 — — 0.14 3.6 Example 9 A9 0.018 0.14 0.82 11.10 5.52 1.68 0.011 0.126 0.087 0.03 0.028 0.007 0.001 — — 0.16 7.3 Example 10 A10 0.018 0.16 0.74 13.80 4.73 1.83 0.013 0.062 0.068 0.03 0.016 0.005 0.002 — 0.09 — 4.2 Example 11 A11 0.023 0.16 0.45 13.04 4.39 2.20 0.011 0.121 0.071 0.04 0.005 0.002 0.001 0.15 — — 5.6 Example 12 A12 0.046 0.16 0.25 12.94 4.23 2.49 0.008 0.186 0.021 0.01 0.010 0.006 0.001 — — 0.16 3.8 Example 13 A13 0.033 0.12 0.32 11.56 5.27 1.83 0.084 0.148 0.086 0.02 0.004 0.003 0.002 — 0.09 — 2.0 Example 14 A14 0.043 0.18 0.23 11.27 4.85 1.64 0.037 0.102 0.063 0.04 0.019 0.004 0.003 — — 0.18 2.1 Example 15 A15 0.013 0.17 0.60 11.38 4.68 2.40 0.047 0.194 0.018 0.03 0.008 0.001 0.002 — 0.06 — 3.5 Comparative B1 0.005 0.17 0.77 14.9 4.33 2.45 0.003 0.192 0.039 0.02 0.003 0.003 0.002 — — — 28.9 Example 1 Comparative B2 0.004 0.15 0.43 13.68 4.32 1.42 0.048 — 0.018 0.04 0.025 0.006 0.001 — — — 0.35 Example 2 Comparative B3 0.049 0.15 0.91 12.86 3.91 2.34 0.089 0.058 — 0.04 0.016 0.003 0.001 — — — 0.42 Example 3 Comparative B1 0.005 0.17 0.77 14.9 4.33 2.45 0.003 0.192 0.039 0.02 0.003 0.003 0.002 — — — 28.9 Example 4 Comparative B2 0.004 0.15 0.43 13.68 4.32 1.42 0.048 — 0.018 0.04 0.025 0.006 0.001 — — — 0.35 Example 5 Comparative B3 0.049 0.15 0.91 12.86 3.91 2.34 0.089 0.058 — 0.04 0.016 0.003 0.001 — — — 0.42 Example 6

[0062] Tubings manufactured from the high strength, high-temperature corrosion resistant martensitic stainless steel of Examples 1-15 and tubings manufactured from the stainless steel of Comparative examples 1-3 were manufactured by the following steps:

[0063] (1) a pipe blank was manufactured;

[0064] (2) a seamless pipe with an outer diameter of 88.9 mm and a wall thickness of 7.34 mm was manufactured from the pipe blank, and then cooled to room temperature;

[0065] (3) quenching: the seamless pipe was heated to a temperature of Ac3 to 1050° C., preferably Ac3 to 1000° C., and heat preservation was performed for t×(0.5-3) min, denoted by the first heat preservation time; and the seamless pipe was subsequently cooled at a cooling rate of 2-40° C./s to a temperature of T1, and heat preservation was performed for t×(0.5-1.5) min, denoted by the second heat preservation time, wherein T1=Ms−80° C., wherein Ms is the temperature at which martensite transformation starts;

[0066] (4) first tempering: the seamless pipe was heated to a temperature of T2 again for tempering treatment and heat preservation was performed for t×(3-7) min, denoted by the third heat preservation time, followed by cooling to 100° C. or less at a cooling rate of 5-30° C./s, wherein T2 ranges from 500° C. to Ac3; and

[0067] (5) second tempering: second tempering treatment was performed at a temperature of T3 and heat preservation was performed for t×(3-7) min, denoted by the fourth heat preservation time, followed by cooling to 100° C. or less at a cooling rate of 5-30° C./s, wherein T3=T2−40° C.;

[0068] wherein t denotes a wall thickness in mm.

[0069] It should be noted that, with reference to Table 1, grades of the stainless steel of Comparative Examples 4-6 respectively correspond to grades of Comparative Examples 1-3, namely B1-B3. For the stainless steel pipes of Comparative Examples 4-6, only the conventional heat treatment method was used, that is, the seamless pipe was heated at 1000° C. for 30 min, air-cooled to room temperature, and then subjected to once tempering heat treatment at 600° C. and heat preserved for 40 min.

[0070] Tables 2-1 and 2-2 list the specific process parameters for each step of the manufacturing method of Examples 1-15 and Comparative Examples 1-3.

TABLE-US-00002 TABLE 2-1 Step (3) Wall Heating First heat Cooling Second heat Ac3 Ms thickness t temperature preservation rate T1 preservation (° C.) (° C.) (mm) (° C.) time (min) (° C./s) (° C.) Time (min) Example 1 855 238 7.34 880 20 5 158 4 Example 2 892 250 7.34 900 15 7 170 4 Example 3 879 240 7.34 880 20 10 160 8 Example 4 872 260 7.34 900 15 30 180 8 Example 5 862 246 7.34 880 20 15 166 10 Example 6 891 289 7.34 900 15 22 209 10 Example 7 877 287 7.34 940 10 40 207 8 Example 8 892 254 7.34 960 4 30 174 8 Example 9 858 262 7.34 880 20 15 182 7 Example 10 876 244 7.34 880 20 10 170 7 Example 11 889 264 7.34 900 15 22 184 5 Example 12 888 262 7.34 920 12 15 182 5 Example 13 856 268 7.34 940 10 20 188 8 Example 14 854 279 7.34 880 20 25 199 8 Example 15 899 277 7.34 960 4 3 197 4 Comparative 915 238 7.34 940 10 5 194 7 Example 1 Comparative 883 272 7.34 900 15 9 188 8 Example 2 Comparative 886 248 7.34 880 20 10 149 10 Example 3 Comparative 915 238 7.34 1000 30 Air cooling, not Example 4 controlled Comparative 883 272 7.34 1000 30 Air cooling, not Example 5 controlled Comparative 886 248 7.34 1000 30 Air cooling, not Example 6 controlled

TABLE-US-00003 TABLE 2-2 Step (4) Step (5) Third heat Cooling Cooling Fourth heat Cooling Cooling T2 preservation rate temperature T3 preservation rate temperature (° C.) time (min) (° C./s) (° C.) (° C.) Time (min) (° C./s) (° C.) Example 1 600 50 5 25 560 25 5 25 Example 2 600 40 5 50 560 30 5 25 Example 3 600 40 5 60 560 35 5 25 Example 4 610 40 5 25 570 35 5 25 Example 5 610 30 5 25 570 50 10 25 Example 6 610 30 5 40 570 40 10 25 Example 7 610 40 10 50 570 40 10 25 Example 8 620 25 10 25 580 50 15 25 Example 9 620 25 10 70 580 50 15 25 Example 10 620 30 10 25 580 35 15 25 Example 11 610 40 10 80 570 35 20 25 Example 12 610 30 30 25 570 25 20 25 Example 13 620 30 30 60 580 35 30 25 Example 14 620 25 10 25 580 25 30 25 Example 15 620 25 10 30 580 35 10 25 Comparative 600 40 10 25 560 35 10 25 Example 1 Comparative 600 30 10 50 560 45 10 25 Example 2 Comparative 610 25 10 25 570 35 10 25 Example 3 Comparative 600 40 Air cooling, not 25 Example 4 controlled Comparative 600 40 Air cooling, not 25 Example 5 controlled Comparative 600 40 Air cooling, not 25 Example 6 controlled

[0071] The related properties such as yield strength YS and tensile strength TS and impact toughness of the tubings manufactured from the high strength, high-temperature corrosion resistant martensitic stainless steel of Examples 1-15 and from the stainless steel of Comparative examples 1-7 were tested to obtain test data for evaluating their properties, respectively, and the specific test items and test methods are as follows:

[0072] 1) Yield strength and tensile strength test: the manufactured steel pipes were processed into API arc specimens, and yield strength test data was obtained by taking an average after testing according to the ISO 6892 standard.

[0073] 2) High temperature yield strength test: the manufactured steel pipes were processed into near-arc specimens and subjected to a high temperature tensile test according to the ISO 6892 standard and the yield strength was obtained by taking an average.

[0074] 3) Charpy V-notch impact absorbing energy (i.e., impact toughness) test: V-notch impact specimens with a volume of 5*10*55 (mm) were taken from steel pipes, and an average was taken after testing according to the GB/T 229 standard and converted to that of a full size of 10*10*55 (mm) according to the API 5CT standard, wherein a test temperature is −20° C.

[0075] 4) Corrosion test in the presence of CO.sub.2 and Cl.sup.− at a high temperature: test specimens were immersed in liquid in an autoclave at a temperature of 180° C. with a CO.sub.2 partial pressure of 6 MPa, a Cl.sup.− concentration of 100000 mg/L and a liquid flow rate of 1 m/s. The test duration was 240 h. The uniform corrosion rate was calculated by comparing the weights of the test specimens before and after the test.

[0076] Table 3 lists the relevant performance parameters for the tubings manufactured from Examples 1-15 and Comparative Examples 1-7.

TABLE-US-00004 TABLE 3 Yield Impact Uniform Strength strength at toughness corrosion YS TS 180° C. at rate (MPa) (MPa) (MPa) −20° C. (J) (mm/a) Example 1 882 912 810 163 0.051 Example 2 963 1002 848 143 0.086 Example 3 908 956 800 161 0.079 Example 4 948 981 843 151 0.062 Example 5 981 1015 861 157 0.094 Example 6 962 995 848 153 0.019 Example 7 993 1025 878 149 0.085 Example 8 970 1001 850 165 0.062 Example 9 989 1037 879 145 0.115 Example 10 934 965 834 163 0.080 Example 11 924 964 831 166 0.100 Example 12 872 902 808 145 0.072 Example 13 996 1043 877 149 0.080 Example 14 905 947 820 162 0.109 Example 15 875 921 810 153 0.090 Comparative 926 964 814 114 0.173 Example 1 Comparative 929 973 817 102 0.166 Example 2 Comparative 930 970 818 108 0.185 Example 3 Comparative 872 915 747 97 0.121 Example 4 Comparative 905 937 760 88 0.138 Example 5 Comparative 882 917 755 86 0.143 Example 6

[0077] As can be seen from Table 3, in Examples 1-15 of the present disclosure, the yield strength YS is 862 MPa or above, meeting 125 ksi requirements, and the yield strength at 180° C. is greater than or equal to 810 MPa; the impact toughness at −20° C. is greater than or equal to 143 J; and the uniform corrosion rate is smaller than or equal to 0.115 mm/a in the environments containing CO.sub.2 and high Cl.sup.− concentration at 180° C. It can be seen that Examples 1-15 of the present disclosure have the advantage of better comprehensive performance compared with Comparative Examples 1-3 and Comparative Examples 4-6. The components in Comparative Examples 1-3 are outside the scope of the present disclosure, wherein the content of Cr element in Comparative Example 1, the content of Mo element in Comparative Example 2, and the content of Ni element in Comparative Example 3 are outside the scope of the present disclosure, and (V+Nb):(C+N) is outside the range of 2:1 to 8:1, resulting in an average corrosion rate of 0.125 mm/a or above and low toughness. In Comparative Examples 4-6, in addition to that the components are outside the scope of the present disclosure, the quenching method and the tempering method are outside the scope of the manufacturing method of the present disclosure, the toughness is further reduced, and the yield strength at high temperature is low. Therefore, compared with the comparative examples, the tubings manufactured from Examples 1-15 of the present disclosure have the significant advantages of excellent high temperature corrosion resistance to carbon dioxide and chloride ions, as well as excellent low-temperature impact toughness and high-temperature strength degradation resistance.

[0078] It should be noted that the above-mentioned examples are merely illustrations of specific examples of the present invention. Obviously, the present invention is not limited to the above examples, but has many similar variations or modifications. All variations or modifications that can be directly derived or easily thought of by those skilled in the art from the contents disclosed in the present disclosure are intended to be within the protection scope of the present invention.