CN111893399A

CN111893399A - High-strength container plate with excellent low-temperature toughness and manufacturing method thereof

Info

Publication number: CN111893399A
Application number: CN202010690127.6A
Authority: CN
Inventors: 谢章龙; 吴俊平; 方磊; 席连云; 张丙军; 李庆春
Original assignee: Nanjing Iron and Steel Co Ltd
Current assignee: Nanjing Iron and Steel Co Ltd
Priority date: 2020-07-17
Filing date: 2020-07-17
Publication date: 2020-11-06
Also published as: WO2022011936A1

Abstract

The invention discloses a high-strength container plate with excellent low-temperature toughness and a manufacturing method thereof, relating to the technical field of steel production, wherein the high-strength container plate comprises the following chemical components in percentage by mass: c: 0.07 to 0.11%, Si: 0.10-0.30%, Mn: 1.30% -1.60%, Ni: 0.40% -0.80%, Mo: 0.05% -0.12%, V: 0.02% -0.05%, Alt: 0.02 to 0.05 percent of the total weight of the alloy, less than or equal to 0.008 percent of P, less than or equal to 0.002 percent of S, and the balance of Fe and inevitable impurities. The strength of the material is upgraded by adding a small amount of alloy, the alloy cost is low, accurate control is easy to realize, the use temperature is lower, the strength is obviously improved, and the material consumption for building the storage tank can be reduced.

Description

High-strength container plate with excellent low-temperature toughness and manufacturing method thereof

Technical Field

The invention relates to the technical field of steel production, in particular to a high-strength container plate with excellent low-temperature toughness and a manufacturing method thereof.

Background

With the high parametric development of steel for the low-temperature container in the chemical industry, certain low-strength mature marks such as 09MnNiDR and the like are difficult to meet the large-scale development requirement of low-temperature spherical tanks such as ethylene and the like, and the method has the advantages that on the basis of ensuring the low-temperature toughness of materials, the material strength is greatly improved so as to reduce the thickness of steel, the toughness risk of a large-thickness steel plate welding joint is reduced, the construction amount and welding seams are reduced, the construction efficiency of equipment is improved, and the material cost is reduced.

In the research and development aspect of domestic high-strength low-temperature steel, Chinese patent with publication number CN110724878A proposes 0.5Ni low-temperature steel and a manufacturing method thereof, B element is added, two-stage controlled rolling, normalizing and tempering process heat treatment is adopted, the lowest use temperature can be reduced to-80 ℃, but the actual yield strength is about 400MPa, and the tensile strength is only about 520 MPa. Chinese patent publication No. CN106467951B proposes a low-temperature steel with high strength, high toughness and low yield ratio for-70 ℃ and a manufacturing method thereof, wherein any one or more of Mo is less than or equal to 0.10, Nb is less than or equal to 0.05, Ti is less than or equal to 0.025 and Ca is less than or equal to 0.005 is added, so that the use requirement of-70 ℃ can be met, but the actual yield strength is less than 400 MPa. Chinese patent with publication number CN108893681A proposes a high-strength high-toughness pressure vessel steel plate and a preparation method thereof, wherein a V-Ni-N alloy system is adopted to improve low-temperature fracture toughness and reduce ductile-brittle transition temperature, and the obtained steel can show good low-temperature high-strength high toughness by utilizing heterogeneous core micro-dispersion effect formed by introducing Mg and Al, N and V component regulation and control means, the yield strength is more than or equal to 480MPa, the tensile strength is 640-740 MPa, the yield ratio is less than or equal to 0.85, the elongation is more than or equal to 21 percent, and the steel plate transversely stretches at 60 ℃ below zero to KV₂Not less than 80J, the ferrite grain size reaches 10.5-13.5 grade, and the lowest use temperature is metThe degree is only-60 ℃.

In conclusion, no report related to low-temperature C-Mn steel with the use temperature of-80 ℃ and the yield strength of more than or equal to 460MPa and the tensile strength of more than or equal to 570MPa exists in the prior art.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-strength container plate with excellent low-temperature toughness, which comprises the following chemical components in percentage by mass: c: 0.07 to 0.11%, Si: 0.10-0.30%, Mn: 1.30% -1.60%, Ni: 0.40% -0.80%, Mo: 0.05% -0.12%, V: 0.02% -0.05%, Alt: 0.02 to 0.05 percent of the total weight of the alloy, less than or equal to 0.008 percent of P, less than or equal to 0.002 percent of S, and the balance of Fe and inevitable impurities.

The technical effects are as follows: according to the invention, the strength of the material is upgraded by adding a small amount of alloy Mo and V, the alloy cost is low, accurate control is easy to realize, the use temperature is lower, the strength is obviously improved, and the material consumption for constructing the storage tank can be reduced.

The technical scheme of the invention is further defined as follows:

the high-strength container plate with excellent low-temperature toughness comprises the following chemical components in percentage by mass: c: 0.07 to 0.08 percent of Si: 0.10-0.21%, Mn: 1.30% -1.55%, Ni: 0.40% -0.47%, Mo: 0.05% -0.07%, V: 0.02% -0.045%, Alt: 0.02-0.038%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, and the balance is Fe and inevitable impurities.

The high-strength container plate with excellent low-temperature toughness comprises the following chemical components in percentage by mass: c: 0.09% -0.10%, Si: 0.15-0.24%, Mn: 1.32% -1.47%, Ni: 0.50% -0.65%, Mo: 0.08-0.11%, V: 0.029% -0.035%, Alt: 0.030-0.044%, P: 0.004-0.005%, S: 0.0007 to 0.002 percent of the total weight of the alloy, and the balance of Fe and inevitable impurities.

The high-strength container plate with excellent low-temperature toughness is characterized in that the thickness of the steel plate is 10-50 mm.

Another object of the present invention is to provide a method for manufacturing a high-strength vessel plate having excellent low-temperature toughness, comprising the steps of continuously casting steel: adopting molten iron pretreatment, converter top and bottom combined blowing smelting, LF + RH refining, and carrying out component control according to component design requirements to produce a blank with the thickness of 260 mm;

heating the plate blank: heating the plate blank to 1130-1160 ℃, wherein the total time in the furnace is more than or equal to 220min, the heat preservation time in the soaking section is 30-60 min, and the temperature uniformity of the whole plate blank is less than or equal to 10 ℃;

rolling and cooling control: removing scale by using high-pressure water after the plate blank is taken out of the furnace, wherein the pressure of the descaling water is more than or equal to 18MPa, controlling rolling in two stages, rolling in an austenite recrystallization region in the first stage, performing finish rolling in an austenite non-recrystallization region in the second stage, and controlling cooling after rolling;

and (3) heat treatment: and performing heat treatment by adopting an off-line quenching and tempering process.

The manufacturing method of the high-strength container plate with excellent low-temperature toughness comprises the following steps of: pretreating molten iron, wherein the content of S in the molten iron is less than 0.002wt%, carrying out converter steelmaking, carrying out deep desulfurization and deoxidation in an LF furnace, adjusting alloy components to reach a target range and controlling superheat degree, degassing in an RH furnace, wherein the vacuum degree is less than or equal to 0.3torr, feeding pure calcium wires for calcium treatment after RH refining, keeping the static stirring time for more than or equal to 15min after wire feeding, continuously casting into blanks with the thickness of 260mm, and carrying out heap cooling treatment on the casting blanks for more than or equal to 48 hours.

The manufacturing method of the high-strength container plate with excellent low-temperature toughness adopts controlled rolling and controlled cooling in the hot rolling process: rolling in an austenite recrystallization region at the first stage, wherein the accumulated reduction of rough rolling is 55-85%, and finish rolling in an austenite non-recrystallization region at the second stage, wherein the accumulated reduction of finish rolling is 50-80%, and the final rolling temperature is 820-860 ℃; and cooling the rolled steel plate by adopting laminar flow, and controlling the temperature of red return to be 600-640 ℃.

The manufacturing method of the high-strength container plate with excellent low-temperature toughness comprises the steps of performing off-line quenching and tempering on the heat treatment, wherein the quenching temperature is 880-910 ℃, the quenching cooling speed is more than or equal to 15 ℃/s, directly quenching to room temperature, heating an off-line quenched steel plate to 600-640 ℃, and tempering for 40-75min to obtain a tempered sorbite structure.

The invention has the beneficial effects that:

(1) the invention has the following design ideas:

c: the steel contains carbon in an increased amount, the yield point and the tensile strength are increased, the tensile strength is increased by about 90MPa and the yield strength is increased by about 40-50 MPa when the carbon content is increased by 0.1%, but the plasticity and the impact property are reduced, the toughness-brittleness transition temperature is increased, the low-temperature toughness of HAZ is harmful, and the strength is ensured during design;

ni: can form alpha and gamma phase solid solutions with Fe, can be infinitely solid-dissolved in gamma phase, can expand gamma phase region, is an austenite forming and stabilizing element, can ensure that screw dislocation is not easy to decompose, ensures the occurrence of cross slip, and improves the plastic deformation performance of the material; ni is also a noble metal element, and the addition amount is reduced as much as possible on the premise of ensuring the performance;

mn: the austenite stabilizing element, which is also a matrix strengthening element, can improve the strength through solid solution strengthening and precipitation strengthening, and when the content is below 1.8 percent, the steel can still keep higher plasticity and toughness when the strength of the steel is improved;

si: deoxidizing elements can be dissolved into ferrite to generate a solid solution strengthening effect, so that the strength and the hardness of the ferrite are improved, but the plasticity and the toughness are reduced to some extent, and the low-temperature toughness of a welding Heat Affected Zone (HAZ) is not facilitated;

mo: the hardenability can be improved, so that the strength is improved, the tempering stability of the steel is improved, and when the steel coexists with chromium or manganese and the like, the tempering brittleness caused by other elements can be reduced or inhibited, but Mo is also a precious metal, and the alloy cost can be obviously improved when the addition amount of Mo is too much; v: the strong carbonitride forming element can improve the strength of steel by refining crystal grains and separating out carbide, when V, Cr and Mo exist simultaneously, complex carbide can be formed in the tempering process to reduce the ductility and toughness of a welding joint, and the V content is strictly controlled for ensuring the ductility and toughness or eliminating stress to avoid cracks;

s and P: s is easy to form a precipitate MnS with Mn, so that the low-temperature toughness is reduced, P is easy to segregate in a grain boundary, the crack propagation resistance of the grain boundary is reduced, and the low-temperature toughness is deteriorated;

al: the main deoxidizing elements in the steel are beneficial to refining crystal grains, and when the content of Al is higher, the inclusion in the steel is increased easily, so that the toughness of the steel is not favorable;

(2) in the invention, the steel plate obtained by adopting off-line quenching and tempering heat treatment has uniform structure performance and good shape control;

(3) the invention obviously improves the low-temperature toughness and strength on the basis of the existing low-temperature C-Mn steel, develops a brand new low-temperature C-Mn steel, can replace the 0.5Ni steel grades at home and abroad such as 09MnNiDR and the like to be used for building low-temperature spherical tanks or storage tanks such as ethylene and the like, and realizes the upgrading of the low-temperature C-Mn steel material.

Drawings

FIG. 1 is a photograph of a tempered structure of a 50mm steel sheet 1/4 thickness corroded by a 4% nital solution.

Detailed Description

The following examples provide a high strength container plate with excellent low temperature toughness and a manufacturing method thereof, wherein the chemical components are shown in table 1, the smelting and rolling process parameters are shown in table 2, the heat treatment process parameters are shown in table 3, and the specific steps are as follows:

steel making and continuous casting: steel making and continuous casting: pretreating molten iron, wherein the content of S in the molten iron is less than 0.002wt%, carrying out converter steelmaking, carrying out deep desulfurization and deoxidation in an LF (ladle furnace), adjusting alloy components to reach a target range and controlling superheat degree, degassing in an RH (relative humidity) furnace, wherein the vacuum degree is less than or equal to 0.3torr, feeding a pure calcium wire for calcium treatment after RH refining, keeping the static stirring time for more than or equal to 15min after wire feeding, continuously casting into a blank with the thickness of 260mm, carrying out dump cooling treatment on a casting blank, and keeping the dump cooling time for more than or equal to 48 hours;

rolling and cooling control: removing scale by using high-pressure water after the plate blank is taken out of the furnace, wherein the pressure of the descaling water is more than or equal to 18MPa, controlling rolling in two stages, rolling in an austenite recrystallization region in the first stage, wherein the accumulated reduction of rough rolling is 55-85%, and finish rolling is carried out in an austenite non-recrystallization region in the second stage, wherein the accumulated reduction of finish rolling is 50-80%, and the finish rolling temperature is 820-860 ℃; cooling the rolled steel plate by adopting laminar flow, and controlling the temperature of red return to be 600-640 ℃;

and (3) heat treatment: and (3) carrying out heat treatment by adopting an off-line quenching and tempering process, wherein the quenching temperature is 880-910 ℃, the quenching cooling speed is more than or equal to 15 ℃/s, directly quenching to room temperature, heating an off-line quenching steel plate to 600-640 ℃, and tempering for 40-75min to obtain a tempered sorbite structure.

TABLE 1

Examples of the invention	C(％)	Mn(％)	Si(％)	S(％)	P(％)	Ni(％)	Mo(％)	V(％)	Al(％)
										Example 1	0.08	1.55	0.21	0.001	0.005	0.47	0.07	0.045	0.038
Example 2	0.10	1.47	0.15	0.0007	0.004	0.50	0.08	0.029	0.044
										Example 3	0.09	1.32	0.24	0.002	0.005	0.65	0.11	0.035	0.030

TABLE 2

TABLE 3

Steel sample	Quenching temperature	Quenching heat preservation time min	Cooling rate in DEG C/s	Tempering temperature of DEG C	Tempering and heat preservation time min
						A	908	30	50	632	47
B	898	40	30	622	55
						C	895	45	18	613	62
D	885	50	16	605	70

The mechanical properties of the products of the examples are shown in table 4,

TABLE 4

Meanwhile, as can be seen from figure 1, the structure obtained by the product is a tempered sorbite structure with the position of the batten kept, has excellent toughness, and can obtain good comprehensive mechanical property, the Charpy impact energy is more than or equal to 150J at the low temperature of-80 ℃, the yield strength is more than or equal to 460MPa, and the tensile strength is more than or equal to 570 MPa. On the basis of the existing 0.5Ni steel, the strength is obviously improved, the wall thickness of the material for constructing the low-temperature spherical tank or the storage tank is reduced, the construction period is shortened, and the cost is saved.

In addition to the above embodiments, the present invention may have other embodiments. All technical solutions formed by adopting equivalent substitutions or equivalent transformations fall within the protection scope of the claims of the present invention.

Claims

1. A high strength container panel having excellent low temperature toughness characterized by: the chemical components and the mass percentage are as follows: c: 0.07 to 0.11%, Si: 0.10-0.30%, Mn: 1.30% -1.60%, Ni: 0.40% -0.80%, Mo: 0.05% -0.12%, V: 0.02% -0.05%, Alt: 0.02 to 0.05 percent of the total weight of the alloy, less than or equal to 0.008 percent of P, less than or equal to 0.002 percent of S, and the balance of Fe and inevitable impurities.

2. The high-strength container plate having excellent low-temperature toughness as claimed in claim 1, wherein: the chemical components and the mass percentage are as follows: c: 0.07 to 0.08 percent of Si: 0.10-0.21%, Mn: 1.30% -1.55%, Ni: 0.40% -0.47%, Mo: 0.05% -0.07%, V: 0.02% -0.045%, Alt: 0.02-0.038%, P is less than or equal to 0.005%, S is less than or equal to 0.001%, and the balance is Fe and inevitable impurities.

3. The high-strength container plate having excellent low-temperature toughness as claimed in claim 1, wherein: c: 0.09% -0.10%, Si: 0.15-0.24%, Mn: 1.32% -1.47%, Ni: 0.50% -0.65%, Mo: 0.08-0.11%, V: 0.029% -0.035%, Alt: 0.030-0.044%, P: 0.004-0.005%, S: 0.0007 to 0.002 percent of the total weight of the alloy, and the balance of Fe and inevitable impurities.

4. The high-strength container plate having excellent low-temperature toughness as claimed in claim 1, wherein: the thickness of the steel plate is 10-50 mm.

5. The method for manufacturing a high-strength container plate having excellent low-temperature toughness as claimed in any one of claims 1 to 4, wherein: comprises that

Steel making and continuous casting: adopting molten iron pretreatment, converter top and bottom combined blowing smelting, LF + RH refining, and carrying out component control according to component design requirements to produce a blank with the thickness of 260 mm;

6. The method of manufacturing a high-strength container plate having excellent low-temperature toughness as claimed in claim 5, wherein: steel making and continuous casting: pretreating molten iron, wherein the content of S in the molten iron is less than 0.002wt%, carrying out converter steelmaking, carrying out deep desulfurization and deoxidation in an LF furnace, adjusting alloy components to reach a target range and controlling superheat degree, degassing in an RH furnace, wherein the vacuum degree is less than or equal to 0.3torr, feeding pure calcium wires for calcium treatment after RH refining, keeping the static stirring time for more than or equal to 15min after wire feeding, continuously casting into blanks with the thickness of 260mm, and carrying out heap cooling treatment on the casting blanks for more than or equal to 48 hours.

7. The method of manufacturing a high-strength container plate having excellent low-temperature toughness as claimed in claim 5, wherein: the hot rolling process adopts controlled rolling and controlled cooling: rolling in an austenite recrystallization region at the first stage, wherein the accumulated reduction of rough rolling is 55-85%, and finish rolling in an austenite non-recrystallization region at the second stage, wherein the accumulated reduction of finish rolling is 50-80%, and the final rolling temperature is 820-860 ℃; and cooling the rolled steel plate by adopting laminar flow, and controlling the temperature of red return to be 600-640 ℃.

8. The method of manufacturing a high-strength container plate having excellent low-temperature toughness as claimed in claim 5, wherein: and (3) performing off-line quenching and tempering on the heat treatment, wherein the quenching temperature is 880-910 ℃, the quenching cooling speed is more than or equal to 15 ℃/s, directly quenching to room temperature, heating the off-line quenched steel plate to 600-640 ℃, and tempering for 40-75min to obtain the tempered sorbite structure.