STEEL FOR GLASS LINING AND PRODUCTION METHOD THEREFOR

Abstract

Steel for glass lining, comprising the following chemical elements in mass percent: C: 0.015-0.060%, Si: 0.01-0.50%, Mn: 0.20-1.5%, P: 0.005-0.10%, Al: 0.010-0.070%, Ti: 0.10-0.30%, and the balance of Fe and other inevitable impurities. The microstructure of the steel for glass lining is a ferrite or a combination of a ferrite and a cementite. In addition, also disclosed is a production method for steel for glass lining, comprising the steps of (1) smelting, refining, and continuous casting to obtain a slab; (2) heating, the heating temperature being 1050-1250° C.; (3) hot rolling, the final temperature of hot rolling being controlled to be 800-920° C.; (4) cooling; and (5) thermal treatment. The steel for glass lining has excellent machinability and low temperature toughness, and also has excellent lining performance.

Claims

1. A steel for glass lining, comprising the following chemical elements in mass percentages: C: 0.015-0.060%; Si: 0.01-0.50%; Mn: 0.20-1.5%; P: 0.005-0.10%; Al: 0.010-0.070%; Ti: 0.10-0.30%; a balance of Fe and other unavoidable impurities; wherein a microstructure of the steel for glass lining is ferrite, or ferrite+cementite.

2. The steel for glass lining according to claim 1, further comprising at least one of the following elements: Cu≤0.50%; Cr≤0.50%; Ni≤0.50%; Mo≤0.50%; wherein the following relationship is satisfied: Cu+Cr+Ni+Mo≤1.0%.

3. The steel for glass lining according to claim 1, wherein the following relationship is satisfied: Ti/C≥3.0.

4. The steel for glass lining according to claim 1, wherein the unavoidable impurity elements include S and N, wherein: S≤0.03%; and/or N≤0.008%.

5. The steel for glass lining according to claim 4, wherein the chemical elements further satisfy: Ti.sub.eff/C≥4.0, wherein Ti.sub.eff=Ti−1.5×S−3.43×N.

6. The steel for glass lining according to claim 1, further comprising at least one of Nb: 0.005-0.10%, V: 0.005-0.05%, and B: 0.0005-0.005%.

7. The steel for glass lining according to claim 6, wherein when Nb and V elements are present, the chemical elements satisfy: Ti+(48/93)Nb+(48/51)V≥4 C.

8. The steel for glass lining according to claim 1, further comprising at least one of Ca: 0.001-0.005% and Mg: 0.0005-0.005%.

9. The steel for glass lining according to claim 1, wherein the mass percentages of the chemical elements further satisfy at least one of: C: 0.02-0.05%; Si: 0.10-0.40%, Mn: 0.50-1.2%; P: 0.005-0.08%.

10. The steel for glass lining according to claim 9, wherein the mass percentage of C is 0.035-0.045%.

11. The steel for glass lining according to claim 1, wherein its properties satisfy at least one of: yield strength: 205-345 MPa; elongation: A50≥30%; Charpy impact energy at −40° C.: Akv≥34 J; and yield ratio≤0.8.

12. A method for manufacturing the steel for glass lining according to claim 1, comprising steps: (1) Smelting, refining, and continuous casting to obtain a slab; (2) Heating: heating temperature: 1050-1250° C.; (3) Hot rolling: controlling a final temperature of hot rolling at 800-920° C.; (4) Cooling; and optionally (5) heat treatment.

13. The method according to claim 12, wherein in step (4), air cooling or water cooling is utilized for the cooling.

14. The method according to claim 13, wherein in step (4), air cooling is utilized for the cooling, wherein a single steel plate is cooled with air, or a stack of steel plates are cooled with air, finally cooling to room temperature; or water cooling is utilized for the cooling, wherein a final cooling temperature of the water cooling is 650-750° C., and a cooling rate is not greater than 50° C./s, followed by air cooling to room temperature.

15. The method according to claim 12, wherein in step (5), a temperature for the heat treatment is 880-980° C., and a hold time in the heat treatment is 30 minutes to 3 hours.

16. The steel for glass lining according to claim 1, wherein the ferrite is comprised of uniform equiaxed grains having an average grain diameter of not greater than 40 μm.

17. The steel for glass lining according to claim 3, wherein the following relationship is satisfied: Ti/C≥4.0.

18. The steel for glass lining according to claim 11, wherein the properties of the steel for glass lining further satisfy at least one of: tensile strength: 400-440 MPa; Charpy impact energy at 0° C.: Akv≥120 J; and Charpy impact energy at −20° C.: Akv≥100 J.

19. The method according to claim 12, wherein the steel for glass lining further comprises at least one of the following elements: Cu≤0.50%, Cr≤0.50%, Ni≤0.50%, Mo≤0.50%, wherein the following relationship is satisfied: Cu+Cr+Ni+Mo≤1.0%; and/or further comprises at least one of Nb: 0.005-0.10%, V: 0.005-0.05%, and B: 0.0005-0.005%; and/or further comprises at least one of Ca: 0.001-0.005% and Mg: 0.0005-0.005%.

20. The method according to claim 12, wherein in the steel for glass lining, the following relationship is satisfied: Ti/C≥3.0, and/or the chemical elements satisfy: Ti.sub.eff/C≥4.0, wherein Ti.sub.eff=Ti−1.5×S−3.43×N.

Description

DESCRIPTION OF THE DRAWINGS

[0075] FIG. 1 shows the microstructure morphology of the steel for glass lining according to the present disclosure in a hot-rolled state in Example 2.

[0076] FIG. 2 shows the microstructure morphology of the steel for glass lining according to the present disclosure after the hot-rolled plate was subjected to 5 runs of simulated high-temperature firing in Example 2.

[0077] The scale in FIGS. 1 and 2 is 100 microns.

DETAILED DESCRIPTION

[0078] The steel for glass lining according to the present disclosure and the method of manufacturing the same will be further explained and illustrated with reference to the specific examples and the accompanying drawings of the specification. Nonetheless, the explanation and illustration are not intended to unduly limit the technical solution of the present disclosure.

Examples 1-6

[0079] The steel for glass lining according to the present disclosure was obtained with the following steps:

[0080] (1) Smelting, refining, and continuous casting to obtain a slab.

[0081] (2) Heating: heating temperature: 1050-1250° C.

[0082] (3) Hot rolling: controlling a final temperature of hot rolling at 800-920° C.

[0083] (4) Cooling: Air cooling or water cooling was utilized. When air cooling was utilized, the steel plate was cooled to room temperature. When water cooling was utilized, the final cooling temperature of the water cooling process was controlled at 650-750° C. The cooling rate was not greater than 50° C./s. Then, the steel plate was cooled in air to room temperature.

[0084] The method in the Examples may further comprise the step of:

[0085] (5) Heat treatment: heat treatment temperature: 880-980° C.; hold time: 30 minutes to 3 hours.

[0086] Table 1 lists the mass percentages of the various chemical elements in the steel for glass lining in Examples 1-6.

TABLE-US-00001 TABLE 1 wt % Chemical Ingredients Ex. C Si Mn P S Al N Ti Cu Cr Ni 1 0.032 0.22 0.96 0.009 0.001 0.033 0.005 0.17 0.015 0.010 — 2 0.033 0.20 0.94 0.090 0.028 0.031 0.008 0.15 0.020 0.025 — 3 0.049 0.21 0.93 0.008 0.030 0.010 0.0055 0.25 0.055 — — 4 0.034 0.22 0.20 0.010 0.001 0.060 0.003 0.19 0.010 0.044 0.012 5 0.055 0.015 0.95 0.010 0.003 0.024 0.004 0.18 — 0.050 0.007 6 0.019 0.35 1.50 0.030 0.005 0.035 0.004 0.10 0.070 0.020 — wt % Chemical Ingredients Cu + Cr + Ni + Mo Ex. Mo Nb V B Ca Mg Ti/C Ti.sub.eff/C (%) 1 0.015 — — 0.001 — — 5.31 4.73 0.04 2 — — — — — — 4.55 2.44 0.05 3 0.010 0.005 0.015 — — — 5.10 3.80 0.07 4 — — 0.035 — — — 5.59 5.24 0.07 5 — 0.015 0.008 — 0.0015 — 3.27 2.94 0.06 6 — 0.05 — 0.0015 — 0.002 5.26 4.15 0.09

[0087] Table 2 lists the specific process parameters of the steps of the manufacturing method in Examples 1-6.

TABLE-US-00002 TABLE 2 Heating Finish Rolling Temperature Temperature Thickness Heat Treatment Ex. (° C.) (° C.) (mm) Post-rolling Cooling Temperature 1 1150 870 20 Air cooling to room temperatures NA 2 1100 820 20 Air cooling to room temperatures NA 3 1250 800 16 Water cooling to 650° C., Holding at 910° C. for average cooling rate 1 hour 45° C./s 4 1200 830 20 Air cooling to room temperatures NA 5 1200 830 10 Air cooling to room temperatures NA 6 1250 910 22 Water cooling to 700° C., Holding at 930° C. for average cooling rate 1 hour 35° C./s

[0088] Table 3 lists the relevant process parameters of the steel for glass lining of Examples 1-6.

TABLE-US-00003 TABLE 3 Impact Test Properties Tensile Test Properties Akv, Akv, Akv, Rp.sub.0.2 R.sub.m A50 R.sub.p0.2/ 0° C. −20°C. −40° C. No. (MPa) (MPa) (%) R.sub.m (J) (J) (J) Enameling Performance Ex. 1 265 409 38 0.648 293 297 288 Single-side enameling, no fish-scaling Ex. 2 285 419 36 0.680 146 112 95 Double-side enameling, no fish-scaling Ex. 3 300 412 37 0.728 124 103 86 Double-side enameling, no fish-scaling Ex. 4 245 416 42 0.589 341 345 353 Single-side enameling, no fish-scaling Ex. 5 312 435 36 0.717 225 187 156 Single-side enameling, no fish-scaling Ex. 6 278 410 44 0.678 356 348 361 Single-side enameling, no fish-scaling

[0089] As it can be seen from Table 3, the steels for glass lining in Examples 1-6 exhibit excellent properties: yield strength 245-312 MPa, elongation A50≥36%, Charpy impact energy at −40° C. Akv≥86 J, and yield ratio R.sub.p0.2/R.sub.m≤0.8, indicating that the steel plates have excellent plasticity and a suitably controlled range of yield strength (that is, the yield strength fluctuates in a small range between different steel plates). When these steels for glass lining are used to make glass-lined containers, no matter in the process of stamping them into end caps or rolling them into can bodies, or in various punching processes, they not only meet the plasticity requirements of various processing and shaping processes, but also do not cause processing difficulties or significant springback due to excessively high strength or hardness of steel plates. In addition, they can reduce the number of times of stamping and rolling.

[0090] In addition, as it can be seen from the impact test toughness in Table 3, the impact energies of the steels for glass lining obtained with different compositions and processing techniques are all higher than 100 J at 0° C. and −20° C., and the impact energies at −40° C. are also higher than the standard requirement of 34 J. They fully meet the requirements of making glass-lined devices at a temperature of −20° C. or lower. They are obviously superior to the steel for glass lining used nowadays. This shows that the above steels for glass lining have excellent processability and low-temperature toughness.

[0091] Each of the above steel plates was sawed into a block sample of 150 mm×150 mm in size. Then, both sides of the sample were polished and shot blasted. The surfaces were cleaned with alcohol for enameling. A vitreous glaze (in which the quartz component was about 71% of the glaze) was used for the enameling. A single-side or double-side wet spraying process was utilized. One base glaze and two top glazes were applied. The firing temperature for the base glaze was 890-920° C., and the firing temperature for the two top glazes was 870-900° C. After the enameling was finished, the samples were let stand at room temperature for a week to observe whether there was fish-scaling on the surfaces. By utilizing the above glaze for glass lining and the above firing process, no fish-scaling was observed. Under the conditions for applying the base glaze and the top glazes, the adherence level reached Class I for all the samples. The tests show that the steel plates according to the present disclosure have good fish-scaling resistance and adherence, fully meeting the processing requirements of manufacturing glass-lined devices such as, inter alia, reactors, storage tanks.

[0092] FIG. 1 shows the microstructure morphology of the steel for glass lining according to the present disclosure in a hot-rolled state in Example 2. As it can be seen from FIG. 1, the microstructure of the steel for glass lining in this example was mainly composed of ferrite under an optical microscope when the steel was in a hot-rolled state. The grains were in a shape of uniform equiaxed grains having an average grain diameter of not greater than 40 μm. When an as-delivered steel plate has such a microstructure, the microstructure will exhibit a hereditary nature. That's to say, the fine and uniform microstructure state still remains after processing, forming and several times of high-temperature firing. Thus, the performances of the glass-lined devices in the service state are improved.

[0093] FIG. 2 shows the microstructure morphology of the steel for glass lining according to the present disclosure after the hot-rolled plate was subjected to 5 runs of simulated high-temperature firing in Example 2. The specific heat treatment process was: 900° C.×10 min+air cooling (1 time).fwdarw.940° C.×10 min+air cooling (1 time).fwdarw.870° C.×10 min+air cooling (3 times). As it can be seen from FIG. 2, the microstructure of the steel for glass lining in this example was still an equiaxed ferrite structure after 5 times of simulated high-temperature firing. Although the grain size was slightly larger than that in the hot-rolled state, it was still fine and uniform.

[0094] It should be noted that the examples set forth above are only specific examples according to the present disclosure. Obviously, the present disclosure is not limited to the above Examples. Similar variations or modifications made thereto can be directly derived or easily contemplated from the present disclosure by those skilled in the art. They all fall in the protection scope of the present disclosure.