EP4624619A1

EP4624619A1 - Glass lined steel having yield strength of 345mpa or above, and manufacturing method therefor

Info

Publication number: EP4624619A1
Application number: EP24741250.5A
Authority: EP
Inventors: Quanshe SUN; Shuangcheng WANG; Jiao WEI; Xiaoyong TAO
Original assignee: Baoshan Iron and Steel Co Ltd
Current assignee: Baoshan Iron and Steel Co Ltd
Priority date: 2023-01-10
Filing date: 2024-01-09
Publication date: 2025-10-01
Also published as: WO2024149253A1; EP4624619A4; CN118326248A

Abstract

The present disclosure provides a steel for glass lining with a yield strength of 345 MPa or more, comprising the following chemical elements in percentage by mass: C: 0.08 ~ 0.14%; Si: 0.16 ~ 0.30%, Mn: 0.80 ~ 1.20%, S: 0.001 ~ 0.015%, P≤0.02%, Al: 0.005 ~ 0.035%, RE: 0.0005 ~ 0.006%, Ti: 0.05 ~ 0.09%, V: 0.01 ~ 0.03%, 0<N≤0.004%, O: 0.001 ~ 0.005%, and at least one of Cu, Cr, Ni and Mo elements, wherein: 0<Cu≤0.08%, 0<Cr≤0.08%, 0<Ni≤0.04%, 0< Mo≤0.04%.

Description

TECHNICAL FIELD

The present disclosure relates to a steel and a manufacturing method therefore, in particular to a steel for glass lining and a manufacturing method therefor.

BACKGROUND

Steel for glass lining is a key material for manufacturing glass lined equipment. It determines the strength and toughness of the overall structure of the glass lined equipment, and to a large extent determines the quality of the glass lining and the service life of the overall equipment. Glass lining process is mainly used for manufacturing glass-lined containers requiring high corrosion resistance and high wear resistance. The most commonly used substrate material for the glass lining process is steel plate. Throughout the entire life cycle from manufacture to service, the glass-lined equipment manufactured with steel plate as the substrate, such as glass-lined reactors and glass-lined storage tanks, makes full use of the advantages such as easy forming, high strength and easy welding of the steel plate and gives full play to the advantages such as high corrosion resistance and high wear resistance of the glass layer. Such properties are in line with the development direction of carbon reduction, energy saving, and environmental friendliness, and thus glass-lined equipment is widely used in the pharmaceutical, chemical and other industries.
The properties of steel plates required for manufacturing glass-lined containers mainly include enamelability for glass lining, mechanical properties and weldability, wherein the steel plates do not occur fish-scaling during single-sided enameling and have a high yield strength are the most basic performance required during the manufacture and service of glass-lined containers.
Currently, glass-lined containers are generally made of Q245R steel plate. However, on one hand, due to the wide range and fluctuation of the steel composition (e.g., the main components of Q245R in GB 713 are the following: C ≤ 0.20%, Si ≤ 0.35%, Mn: 0.50 ~ 1.10%), fish-scaling may occur occasionally during enameling due to insufficient hydrogen traps in the steel; on the other hand, since the microstructure of the steel is mainly pearlite and ferrite, the higher the pearlite content, the more gases such as CO are produced during the enameling and firing process. These gases gather into bubbles or large bubbles in the glass layer, which will seriously damage the corrosion resistance and surface quality thereof.
Furthermore, in order to improve the pressure resistance of glass-lined containers and meet the requirements of thinning and light weight of glass-lined containers, some technical solutions use the Q345R steel plate with higher strength. However, the Q345R steel plate has higher carbon and pearlite contents than those of the Q245R steel plate, so the harm of bubble production will be more prominent. At the same time, the silicon and manganese contents are also high, which is very unfavorable for improving the enameling performance and glass layer quality.
Therefore, it is expected to obtain a steel for glass lining with a yield strength of 345 MPa or more, which not only meet various performance requirements such as mechanical performance, but also achieve thinning and light weight of glass-lined containers.

SUMMARY

One of the objectives of the present disclosure is to provide a steel for glass lining with a yield strength of 345 MPa or more, which not only satisfies the requirements of forming, welding and enameling for making glass-lined containers, but also achieve thinning or lightening of glass-lined containers. The steel can also reduce the number of enameling and firing times, improve the processing efficiency, reduce energy consumption and the use of glaze, and improve the quality of the glass lining layer when performing the glass lining process.
In order to achieve the above objective, the present disclosure provides a steel for glass lining with a yield strength of 345 MPa or more, comprising, in addition to Fe and inevitable impurities, the following chemical elements in mass%:

C: 0.08 ~ 0.14%,
Si: 0.16 ~ 0.30%,
Mn: 0.80 ~ 1.20%,
S: 0.001 ~ 0.015%,
Al: 0.005 ~ 0.035%,
RE: 0.0005 ~ 0.006%,
Ti: 0.05 ~ 0.09%,
V: 0.01 ~ 0.03%,
0 < N ≤ 0.004%,
O: 0.001 ~ 0.005%.

The present disclosure further provides a steel for glass lining with a yield strength of 345 MPa or more, comprising the following chemical elements in mass%:

C: 0.08 ~ 0.14%,
Si: 0.16 ~ 0.30%,
Mn: 0.80 ~ 1.20%,
S: 0.001 ~ 0.015%,
Al: 0.005 ~ 0.035%,
RE: 0.0005 ~ 0.006%,
Ti: 0.05 ~ 0.09%,
V: 0.01 ~ 0.03%,
0 < N ≤ 0.004%,
O: 0.001 ~ 0.005%, and
the balance being Fe and inevitable impurities.

Preferably, the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure further comprises at least one of the following chemical elements: $0 < Cu \leq 0.08 %,$ $0 < Cr \leq 0.08 %,$ $0 < Ni \leq 0.04 %,$ $0 < Mo \leq 0.04 % .$
Preferably, the inevitable impurities of the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure comprise P, and the content of P satisfies: P ≤ 0.02%.
In the present disclosure, carbon, silicon and manganese are used as basic strengthening elements when designing the composition. Carbon, silicon and manganese are the main strengthening elements that enable the yield strength of steel plate to reach 345MPa or more. The forms of carbon existed in the steel include pearlite, carbide precipitation and solid solution carbon.
The present disclosure adds an appropriate amount of vanadium on the basis of adding an appropriate amount of alloying element titanium, and the vanadium forms vanadium carbonitride or vanadium carbide in the steel. By controlling the hot rolling and cooling process, fine and dispersedly distributed vanadium carbonitride or vanadium carbide is precipitated, especially the precipitation phase at the ferrite grain boundary can significantly improve the strength of the steel.
In addition, the present disclosure adds a very small amount of rare earth elements on the basis of adding an appropriate amount of alloying element titanium, which is conducive to improving the continuous castability during continuous casting of the steel.
Specifically, in the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure, the design principles of each chemical element are as follows:
C: C is an element that effectively improves the strength of the steel plate. By controlling the hot processing process and the cooling process, the form of carbon existed in the steel are pearlite, carbide, solid solution, etc., and the cooling rate is controlled to prevent them from transforming into bainite, martensite and other structures. On one hand, the pearlite and carbide precipitated in the steel has a strengthening effect, and an appropriate amount of pearlite structure is conducive to stabilizing the strength of the steel before and after glass lining firing; on the other hand, during the enameling, the pearlite and precipitated carbide become traps for capturing hydrogen in the steel, which supplements the anti-fishscaling performance of the steel plate. However, during enameling and high-temperature firing, pearlite decomposes and produces CO gas, which is likely to resulting to bubble defects in the glass layer or on the surface, affecting the quality and practical performance of the glass layer. Therefore, in the present disclosure, the pearlite content in the steel is reduced by controlling the carbon content in the steel and adding alloying elements that form strong carbide, and preventing it from transforming into bainite, martensite and other structures through process control such as cooling rate. Compared with Q345R steel plate (see GB 713-2014 ) in which carbon mainly exists in the form of pearlite (due to no addition or very small addition of alloy elements that form carbides such as titanium, vanadium), the carbon content in the present disclosure (C: 0.08-0.14%) is not only lower than Q345R, but also lower than conventional Q245R having a carbon content of 0.20% (see GB 713-2014 ). In addition, in the present disclosure, strong carbide forming elements such as titanium and vanadium are also added, which can significantly reduce the content of pearlite because part of the carbon will exist in the form of carbide.
Si: Si is a strengthening element, but excessive silicon content will impair the adhesion between the glass layer and the steel plate. In the glass lining process, if the number of enameling times of the ground glaze is reduced to once or the ground glaze is omitted, the adhesion between the steel plate and the cover glaze needs to be improved. In the steel for glass lining described in the present disclosure, the Si element content in mass percentage is controlled at a relatively low level, i.e., 0.16 ~ 0.30%.
Mn and Al: Mn is a strengthening element, and the purpose of adding manganese to a steel is to improve the strength of the steel. However, the addition of too much manganese will not only increase the alloy cost, but also increase bubble defects with the increase of the manganese content, which will damage the quality of the glass layer. Therefore, in the present disclosure, the manganese content is controlled to 0.80 ~ 1.20%. In addition, manganese and aluminum are both deoxidizing elements, and the addition of manganese and aluminum can both reduce the oxygen content in steel. On this basis, Al is controlled to 0.005-0.035% in the present disclosure.
RE, O and S: Rare earth elements (RE) are mainly cerium, lanthanum or a mixture of cerium and lanthanum, they easily form rare earth oxides or oxysulfides with oxygen and/or sulfur in steel. Because these inclusions have high formation temperature and usually begin to form in molten steel, therefore, the quantity and form of these compounds are relatively stable in the steel and are less influenced by subsequent hot processing. Thus, they are relatively stable and reliable hydrogen traps when manufacturing glass lining and can replace part of titanium to reduce the amount of titanium added to steel. On this basis, the contents of rare earth elements, oxygen and sulfur are controlled to: RE: 0.0005-0.006%, O: 0.001-0.005%, S: 0.001-0.015%.
V: V is a strong carbide and nitride forming element. Vanadium forms compounds such as VN, VC or V (CN) in the steel. In the present technical solution, in titanium-added steel, since the contents of titanium and nitrogen are controlled so that titanium preferentially forms titanium nitride inclusions with nitrogen, vanadium mainly forms V (CN) or VC. During the reheating process of the continuously casted slab, because the solubility of VC or V (CN) compounds of V is high, that is to say, they can be dissolved within an appropriate reheating time at a conventional reheating temperature, thus, on one hand, in the subsequent hot rolling process, it is easy to precipitate particles with more dispersed distribution and smaller size, achieving refinement and homogenization, which can not only improve the hydrogen trap effect of these particles, but also prevent the growth of ferrite grains. In other words, compared with titanium, vanadium has lower precipitation temperature and is more affected by hot processing. Thererfore the precipitation of vanadium can be reversely controlled by reasonably controlling the hot rolling temperature, rolling process and cooling process, achieving the improvement effects of vanadium precipitation on strength and hydrogen storage traps. On the other hand, the titanium nitride formed by adding titanium can prevent the growth of austenite grains during heating. Based on the characteristics in terms of precipitation strengthening and improving the hydrogen storage capacity provided by the formed particles such as VC or V (CN), the amount of V added in the present disclosure is V: 0.01-0.03%.
Ti and N: N is very easy to form titanium nitride inclusions with Ti in preference to V in steel, and the higher the contents of titanium and nitrogen, the greater the solubility products of nitrogen and titanium, the higher the formation temperature of titanium nitride and the larger the diameter of the formed particles. Titanium nitride particles are beneficial hydrogen traps in steel, but large particles of titanium nitride inclusions weaken the hydrogen trap effect, harming plasticity and toughness seriously. Therefore, in the present disclosure, the formation of coarse titanium nitride inclusions is avoided by controlling nitrogen and titanium to relatively low contents of 0 < N ≤ 0.004% and Ti 0.05 ~ 0.09%, so as to optimize the effect of titanium nitride on hydrogen storage and plasticity and toughness.
Cu, Ni, Cr and Mo: They are all residual elements in steel, so the inventors do not intentionally add these elements. A very small amount of Cu, Ni, Cr and Mo is beneficial to the adhesion between the steel plate and the glass layer, but when the contents are too high, the adhesion between the steel plate and the glass layer will be hindered. Therefore, when these elements are present in steel, their contents are controlled as follows: 0 < Cu ≤ 0.08%, 0 < Cr ≤ 0.08%, 0 < Ni ≤ 0.04%, 0 < Mo ≤ 0.04%.
Preferably, the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure has a microstructure of ferrite + dispersed pearlite, and does not comprise martensite structure or bainite structure.
The term "dispersed" means that the pearlite in the steel is basically discontinuous or not in a band shape. Specifically, the continuous pearlite structure has a maximum length of not more than 50 µm, preferably not more than 30 µm.
Preferably, the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure has inclusions including rare earth oxides and rare earth oxysulfides.
Preferably, the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure has a yield strength of ≥ 345 MPa, a tensile strength of ≥ 450 MPa, a total elongation A₅₀ of ≥ 27%, and a Charpy impact energy Akv at 0°C of ≥ 120 J.
Preferably, the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure has a thickness of 8-40 mm.
Another objective of the present disclosure is to provide a method for manufacturing a steel for glass lining with a yield strength of 345 MPa or more. The manufacturing method is short in process and has simple process operation, easy-to-control process parameters and high production efficiency.
Based on the above objective, the present disclosure provides a method for manufacturing a steel for glass lining with a yield strength of 345 MPa or more, comprising the following steps in sequence:

(1) smelting, refining and continuous casting to obtain a slab;
(2) heating;
(3) hot rolling;
(4) air cooling or water cooling.

Preferably, in the method for manufacturing a steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure, the rolled steel plate can be directly air-cooled to room temperature, or water-cooled to the required final cooling temperature and then air-cooled to room temperature. Step of forced cooling or heat treatment is not required. Therefore, the method is short in process, and has simple manufacturing process, high production efficiency, and low manufacturing cost.
In the method for manufacturing a steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure, the purpose of smelting and refining is to ensure the basic composition of the molten steel, removing impurity elements and harmful gases in the steel, and adding alloying elements such as manganese, aluminum, silicon, then alloying elements such as titanium and vanadium are added and undergo sufficient homogenizing and chemical composition adjustment. Finally, rare earth alloying elements including cerium, lanthanum and mixture thereof are added in the form of alloys or by wire feeding. In addition, continuous casting can effectively ensure uniform composition within the slab and good surface quality of the slab. The continuously casted slab can have a thickness varying from 200 mm to 350 mm based on the thickness of the finished steel plate.
Preferably, in step (2) of the manufacturing method according to the present disclosure, the heating temperature is controlled to be 1100 ~ 1200°C.
In step (2), the slab is reheated at a heating temperature which is controlled to 1100 ~ 1200°C. During the heating process, as the temperature of the slab increases to enter the austenization region, the structure in the steel will transform into austenite, then the transformation and homogenization of the austenite structure is completed under sufficient heating and holding conditions. The rare earth inclusions, titanium nitride and sulfide (manganese titanium) formed in the continuously casted slab are basically unaffected within this heating temperature range, in other words, they are rarely dissolved during heating, while vanadium compounds are dissolved almost completely.
Preferably, in step (3) of the manufacturing method according to the present disclosure, the finishing temperature of the hot rolling is controlled to 820-900°C.
In the hot rolling process according to the present disclosure, the finishing temperature of the hot rolling is controlled within a relatively high temperature range of 820-900°C. This is because: within this temperature range, the microstructure of the rolled steel completes phase transformation and fully recrystallize, forming pearlite and ferrite structures. During the rolling and cooling process, the solid-dissolved vanadium precipitates into VC and V (CN) particles, while the state of inclusions such as rare earth compounds and titanium nitride generated during the continuous casting process is relatively stable and rarely affected by the hot rolling reheating and rolling process.
Preferably, in step (4) of the manufacturing method according to the present disclosure, when water cooling is adopted for cooling, the cooling rate is controlled to ≤ 50°C/s, and the final cooling temperature is controlled to 550 ~ 750°C.
The steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure can be obtained by the above steps (1) - (4) without additional heat treatment. The obtained steel plate can be further processed and manufactured into glass-lined products such as single-sided glass-lined containers through cutting, forming, welding, surface treatment, enameling, firing. During the enameling process, one or two times of ground glaze sprayings in combination with multiple times of cover glaze sprayings is allowed; alternatively, multiple times of cover glaze sprayings without ground glaze is also possible. The firing temperature can be 860 ~ 930°C.
The steel for glass lining with a yield strength of 345 MPa or more and the manufacturing method thereof according to the present disclosure have the following beneficial effects:
In the present disclosure, the addition of alloying elements such as titanium, vanadium, and a small amount of rare earth elements allows the steel to have sufficient hydrogen traps that are rarely affected by subsequent processing and can be stably controlled, and can prevent the blockage of the tap during continuous casting to achieve smooth continuous castability. This further allows the steel to be enameled with ground glaze only once or directly enameled with cover glaze without ground glaze during the processing of glass-lined products, so that the number of enameling or firing times is reduced.
Compared with Q245R or Q345R steel, in the present disclosure, the strength of the steel plate is improved by strengthening mechanisms such as solid solution strengthening provided by alloying elements silicon, manganese and vanadium, as well as precipitation strengthening provided by titanium and vanadium, while the carbon content of the steel plate is reduced, which is beneficial to improving the plasticity and toughness, weldability and anti-bubbling of the glass lining of the steel plate. The reduction of carbon content in steel can significantly delay the transformation of pearlite and ferrite to austenite and prevent the growth of austenite grains during the heating process of glass lining firing.
Compared with Q245R steel plate, the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure has a reduced thickness. When it is used for glass-lined pressure containers, the wall thickness of the container can be reduced by 10% or more, achieving lightweight.
Since the pearlite content in the steel for glass lining with a yield strength of 345 MPa or more according to the present disclosure is significantly less than that in the commonly used Q245R or Q345R steel plates, the quality of the glass glaze layer can be significantly improved.
The manufacturing method described in the present disclosure adopts a controlled rolling process. The rolled steel plate does not need heat treatment. The manufacturing method is short in process and has high production efficiency and low manufacturing cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a metallographic structure photograph of the steel for glass lining with a yield strength of 345 MPa or more in Example 3 of the present disclosure under an optical microscope.
FIG. 2 is a precipitation phase photograph of the steel for glass lining with a yield strength of 345 MPa or more in Example 3 of the present disclosure under a transmission electron microscope.

DETAILED DESCRIPTION

The steel for glass lining with a yield strength of 345 MPa or more and manufacturing method thereof described in the present disclosure will be further explained and illustrated with reference to the specific examples. However, the explanations and illustrations do not constitute an undue limitation on the technical solutions of the present disclosure.

Examples 1-7

The steel for glass lining with a yield strength of 345 MPa or more in Examples 1-7 was prepared by the following steps:

(1) smelting and refining;
(2) continuous casting to obtain a slab with a thickness of 200-350 mm;
(3) heating: controlling the heating temperature to 1100-1200°C;
(3) hot rolling: performing several rolling passes and controlling the finishing temperature of the hot rolling to 820-900°C;
(4) air cooling or water cooling: when water cooling was adopted, the cooling rate was controlled to ≤ 50°C/s, the final cooling temperature was controlled to 550-750°C, and then air cooling or stack cooling was performed to room temperature; when air cooling was adopted, the final cooling temperature was room temperature.

Table 1 lists the mass percentage of each chemical element in the steel for glass lining with a yield strength of 345 MPa or more in Examples 1-7.

Table 1. (wt%, the balance is Fe and inevitable impurities except for P)

Examples	C	Si	Mn	P	S	Al	Ti	N	O	V	RE	Cu	Cr	Ni	Mo
1	0.090	0.25	0.95	0.011	0.008	0.015	0.09	0.0040	0.002	0.010	0.0005	0.08	0.04	0.007	0.040
2	0.140	0.20	1.01	0.009	0.005	0.023	0.07	0.0033	0.005	0.018	0.0020	0.06	0.08	0.005	0.006
3	0.090	0.21	0.95	0.005	0.001	0.005	0.08	0.0030	0.004	0.025	0.0010	0.04	0.04	0	0.005
4	0.120	0.16	0.80	0.015	0.010	0.025	0.05	0.0015	0.003	0.030	0.0060	0	0	0	0
5	0.080	0.30	1.20	0.020	0.015	0.035	0.09	0.0035	0.001	0.015	0.0020	0.05	0	0.012	0.014
6	0.085	0.19	0.85	0.013	0.014	0.029	0.08	0.0013	0.002	0.015	0.0015	0.04	0.06	0.008	0.004
7	0.100	0.23	0.90	0.015	0.003	0.010	0.05	0.0030	0.005	0.020	0.0010	0.06	0.07	0.012	0.014

Table 2 lists the specific process parameters in the above process steps for the steel for glass lining with a yield strength of 345 MPa or more in Examples 1-7.

Table 2

Examples	Thickness of slab (mm)	Thickness of steel plate (mm)	Step (3)	Step (4)	Step (4)
Examples	Thickness of slab (mm)	Thickness of steel plate (mm)	Heating temperature (°C)	Finishing temperature of hot rolling (°C)	Cooling manner	Cooling rate (°C/s)	Final cooling temperature (°C)
1	250	35	1150	880	Water cooling	35	580
2	200	10	1100	850	Air cooling	-	Room temperature
3	200	16	1120	860	Air cooling	-	Room temperature
4	250	40	1180	900	Water cooling	30	650
5	200	18	1200	860	Air cooling	-	Room temperature
6	230	8	1160	845	Air cooling	-	Room temperature
7	350	25	1180	900	Water cooling	20	750

FIG. 1 is a metallographic structure photograph of the steel for glass lining with a yield strength of 345 MPa or more in Example 3 of the present disclosure under an optical microscope. It can be seen from FIG. 1 that the steel plate for glass lining has a microstructure of ferrite + a small amount of pearlite (white is ferrite, black is pearlite), wherein the pearlite is dispersedly distributed rather than distributed as a band and has a maximum length of not more than 30 µm. The microstructure does not comprise martensite or bainite structure.
FIG. 2 is a precipitation phase photograph of the steel for glass lining with a yield strength of 345 MPa or more in Example 3 of the present disclosure under a transmission electron microscope. V (CN) that distributes along the ferrite grain boundary (black structure) can be seen from FIG. 2.
The tensile specimens and impact specimens of the steel plates for glass lining in Examples 1-7 were sampled and prepared according to the principle of sampling along 1/4 thickness and transversely as described in GB/T 2975 , in which:
The tensile specimens were processed into circular tensile specimens, 3 pieces per group. The yield strength, tensile strength and total elongation were tested respectively according to the tensile test method at room temperature of GB/T 228 , and the average value was taken; the impact specimens were processed into Charpy impact specimens, and the notch shape of the specimens was KV2, 3 pieces per group. The impact value at 0°C was tested according to the impact test method of GB/T 229 , and the average value was taken. The test results obtained are listed in Table 3.

Table 3 lists the mechanical performance test results of the steel for glass lining with a yield strength of 345 MPa or more in Examples 1-7.

Table 3

Examples	Tensile performance			Impact performance
Examples	Yield strength Rp0.2 or ReL (MPa)	Tensile strength Rm (MPa)	Total elongation A₅₀ (%)	Impact energy at 0°C KV2 (j)
1	436	494	28	342
2	413	484	30	124
3	375	461	32	318
4	421	478	27	236
5	384	454	32	156
6	433	485	29	176
7	440	499	31	282

It can be seen from Table 3 that the steel for glass lining with a yield strength of 345 MPa or more in Examples 1-7 has a yield strength of ≥ 375 MPa, a tensile strength of ≥ 454 MPa, a total elongation A₅₀ of ≥ 27%, and a Charpy impact energy at 0°C Akv of ≥ 124 J. It can be seen that the steel for glass lining with a yield strength of 345 MPa or more has high strength and low-temperature toughness.
It should be noted that the combination of the technical features of the present disclosure is not limited to the combinations described in the claims or the specific embodiments of the present disclosure, and all the technical features described in the present disclosure can be freely combined in any way unless contradicted with each other.
It should also be noted that the embodiments demonstrated above are only specific examples of the present disclosure. It is obvious that the present disclosure is not limited to the above embodiments, and various similar changes or modifications can be made. Such changes or modifications can be directly obtainable or easily conceivable for those skilled in the art from the disclosure in the present disclosure, and all of which fall within the scope of the present disclosure.

Claims

A steel for glass lining with a yield strength of 345 MPa or more, comprising, in addition to Fe and inevitable impurities, the following chemical elements in mass%:
C: 0.08 ~ 0.14%,

Si: 0.16 ~ 0.30%,

Mn: 0.80 ~ 1.20%,

S: 0.001 ~ 0.015%,

Al: 0.005 ~ 0.035%,

RE: 0.0005 ~ 0.006%,

Ti: 0.05 ~ 0.09%,

V: 0.01 ~ 0.03%,

0<N≤0.004%,

O: 0.001 ~ 0.005%.
The steel for glass lining according to claim 1, wherein the steel for glass lining comprises the following chemical elements in mass%:
C: 0.08 ~ 0.14%,

Si: 0.16 ~ 0.30%,

Mn: 0.80 ~ 1.20%,

S: 0.001 ~ 0.015%,

Al: 0.005 ~ 0.035%,

RE: 0.0005 ~ 0.006%,

Ti: 0.05 ~ 0.09%,

V: 0.01 ~ 0.03%,

0<N≤0.004%,

O: 0.001 ~ 0.005%, and

the balance being Fe and inevitable impurities.
The steel for glass lining according to claim 1 or 2, wherein the steel for glass lining further comprises at least one of the following chemical elements: $0 < Cu \leq 0.08 %,$ $0 < Cr \leq 0.08 %,$ $0 < Ni \leq 0.04 %,$ $0 < Mo \leq 0.04 % .$
The steel for glass lining according to claim 1 or 2, wherein the inevitable impurities comprise P, and the content of P satsifies: P≤0.02%.
The steel for glass lining according to claim 1 or 2, wherein the steel for glass lining has a microstructure of ferrite + dispersed pearlite.
The steel for glass lining according to claim 5, wherein the pearlite structure has a maximum length of not more than 50µm.
The steel for glass lining according to claim 5, wherein the microstructure of the steel for glass lining does not comprise martensite or bainite.
The steel for glass lining according to claim 1 or 2, wherein the steel for glass lining has inclusions including rare earth oxides and rare earth oxysulfides.
The steel for glass lining according to claim 1 or 2, wherein the steel for glass lining has a precipitation phase at ferrite grain boundaries, and the precipitate phase is vanadium carbonitride or vanadium carbide.
The steel for glass lining according to claim 1 or 2, wherein the steel for glass lining has a yield strength of ≥345MPa, a tensile strength of ≥450MPa, a total elongation A₅₀ of ≥27%, and a Charpy impact energy at 0°C Akv of ≥120J.
The steel for glass lining according to claim 1 or 2, wherein the steel for glass lining has a thickness of 8 ~ 40mm.
A method for manufacturing the steel for glass lining with a yield strength of 345 MPa or more according to any one of claims 1 to 11, wherein the method comprises the following steps in sequence:
(1) smelting, refining and continuous casting to obtain a slab;

(2) heating;

(3) hot rolling;

(4) air cooling or water cooling.
The method according to claim 12, wherein in step (2), the heating is performed at a temperature of 1100 ~ 1200°C.
The method according to claim 12, wherein in step (3), a finishing temperature of the hot rolling is 820 ~ 900°C.
The method according to claim 12, wherein in step (4), water cooling is adopted for cooling at a cooling rate of ≤50°C/s with a final cooling temperature of 550 ~ 750°C; or, in step (4), air cooling is adopted for cooling with a final cooling temperature of room temperature.
The method according to claim 12, wherein the method does not comprise a step of forced cooling or heat treatment.