CN112267075A - Precipitation type reinforced alloy and preparation method thereof - Google Patents
Precipitation type reinforced alloy and preparation method thereof Download PDFInfo
- Publication number
- CN112267075A CN112267075A CN202011156140.XA CN202011156140A CN112267075A CN 112267075 A CN112267075 A CN 112267075A CN 202011156140 A CN202011156140 A CN 202011156140A CN 112267075 A CN112267075 A CN 112267075A
- Authority
- CN
- China
- Prior art keywords
- alloy steel
- precipitation
- low carbon
- carbon alloy
- rolling
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
- C21D8/0226—Hot rolling
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
- C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
- C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/001—Austenite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/008—Martensite
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention belongs to the technical field of alloy steel, and particularly relates to precipitation-strengthened ultra-low carbon alloy steel and a preparation method thereof. The precipitation strengthening type ultra-low carbon alloy steel provided by the invention comprises the following element components in percentage by mass: 0.001 to 0.01% of C, 0.5 to 1.2% of Si, 1.2 to 3.5% of Mn, 2.0 to 5.0% of Ni, 0.2 to 0.8% of Co, 1.0 to 3.5% of Cu, 0.8 to 1.8% of Al, 0 to 0.005% of B, and the balance of Fe and inevitable impurities. The alloy steel does not contain any strong carbide forming element, no carbide is precipitated in the preparation process, and the main strengthening phases are a Cu-rich precipitated phase and a NiAl precipitated phase. When the strength is ensured by composite precipitation strengthening, the reverse transformation austenite increases the plasticity and toughness, the ultralow C content improves the welding performance, and the application range of the alloy steel is further widened.
Description
Technical Field
The invention belongs to the technical field of alloy steel, and particularly relates to precipitation-strengthened ultra-low carbon alloy steel and a preparation method thereof.
Background
High strength and high toughness have been the goals sought for thick plate structural steels. The existing strengthening means mainly include solid solution strengthening, precipitation strengthening, fine crystal strengthening, dislocation/deformation strengthening and the like, wherein the precipitation strengthening is an important and effective strengthening means. Therefore, the high strength steel is generally strengthened by introducing second phase particles such as carbide, a Cu-rich precipitated phase and a NiAl precipitated phase, for example, in a patent "a high strength and high toughness thick plate structural steel for low temperature and a heat treatment method thereof" (patent No. 201911053453.X) and a patent "Cu-rich nanocluster strengthened ultrahigh strength ferrite steel and a manufacturing method thereof" (publication No. CN104046917B), the second phase composite strengthening of two or more than two of the carbide, the Cu-rich precipitated phase and the NiAl precipitated phase can be realized through corresponding treatment processes, so as to achieve the purpose of improving the strength. However, high toughness, especially good low temperature impact toughness, is a prerequisite for ensuring the service performance and service life of high-strength steels and the safety of related components. At present, the conventional means for improving the toughness mainly comprise two types: one is to increase the content of toughening elements, particularly Ni, because the ductile-brittle transition temperature is reduced by about 20 ℃ per 1 wt.% increase in Ni, but this also increases the material cost; the other is to control the toughened reversed austenite phase through multi-step heat treatment, but this increases the process cost. At present, the steel plate or the forge piece as the structural steel plate or the forge piece for low temperature mainly balances the material cost and the process cost on the premise of meeting the strength requirement. In addition, high alloy content impairs the weldability to some extent, while off-line multi-step heat treatment leads to a reduction in strength due to the growth of precipitated phases. Therefore, in the field of high-strength steel, whether a new composition-process combination scheme for improving toughness and weldability exists is a problem to be solved.
Disclosure of Invention
In view of the above, the invention provides a precipitation strengthening type ultra-low carbon alloy steel without strong carbide forming elements, which takes a Cu-rich precipitation phase and a NiAl precipitation phase as main strengthening sources and takes reverse transformation austenite as a main toughening source.
The invention provides precipitation strengthening type ultra-low carbon alloy steel which comprises the following element components in percentage by mass:
the invention also provides a preparation method of the precipitation strengthening type ultra-low carbon alloy steel in the technical scheme, which comprises the following steps:
smelting alloy raw materials according to the element proportion to obtain a casting blank;
preparing the precipitation-strengthened ultra-low carbon alloy steel from the casting blank according to any one of modes 1-3;
mode 1: rolling the casting blank and then carrying out ultra-fast cooling to obtain the precipitation-strengthened ultra-low carbon alloy steel; the rolling is rough rolling and finish rolling or warm rolling;
mode 2: carrying out rough rolling and finish rolling on the casting blank, cooling to room temperature, and sequentially carrying out austenitizing treatment and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel;
mode 3: and cooling the casting blank to room temperature after rough rolling and finish rolling, and sequentially carrying out austenitizing treatment, two-phase region critical tempering and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel.
Preferably, in the mode 1, the temperature of the finish rolling or warm rolling is 580-690 ℃, the deformation amount of the finish rolling or warm rolling is 16-40%, and the cooling rate is 15-51 ℃/s.
Preferably, the austenitizing treatment in the modes 2 and 3 is carried out at a temperature of 810 to 890 ℃ for 0.5 to 3 hours.
Preferably, the temperature of the tempering treatment in the modes 2 and 3 is 475 to 550 ℃, and the time is 0.5 to 6 hours.
Preferably, in the method 3, the temperature of the critical tempering treatment in the two-phase region is 625-680 ℃, and the time is 0.5-2 hours.
Preferably, the precipitation strengthening type ultra-low carbon alloy steel obtained by the preparation method has a ferrite matrix structure and an average grain size of 2-20 μm.
Preferably, the precipitation strengthening type ultra-low carbon alloy steel obtained by the preparation method is characterized in that strengthening phases in a microstructure are a Cu-rich precipitation phase and a NiAl precipitation phase which are in a nano-coherent structure, the average size is 1.8-15 nm, the spacing is 1.5-50 nm, and the number density is 1023～1024m-3A rank.
Preferably, the precipitation-strengthened ultra-low carbon alloy steel obtained by the preparation method is characterized in that the toughening phase in the microstructure is an austenite phase, is mainly distributed at interfaces such as martensite laths or the like or prior austenite grain boundaries, and has a volume fraction of 5-25%.
Preferably, the precipitation strengthening type ultra-low carbon alloy steel obtained by the preparation method is characterized by having yield strength of 700-1180 MPa, tensile strength of 850-1250 MPa, elongation of 10-20%, impact energy at room temperature of 20-300J and impact energy at-80 ℃ of 8-250J.
The invention provides precipitation strengthening type ultra-low carbon alloy steel which comprises the following element components in percentage by mass: 0.001-0.01% of C, 0.5-1.2% of Si, 1.2-3.5% of Mn, 2.0-5.0% of Ni, 0.2-0.8% of Co, 1.0-3.5% of Cu, 0.8-1.8% of Al, 0-0.005% of B and the balance of Fe. The main strength source of the precipitation strengthening type ultra-low carbon alloy steel is the composite strengthening of a Cu-rich precipitation phase and a NiAl precipitation phase, and the main toughness source is the component design of a reverse transformation austenite phase, ultra-low carbon and no strong carbide forming element. The content of C in the precipitation-strengthened ultra-low carbon alloy steel provided by the invention can be as low as 0.001 wt.%, and is not more than 0.01 wt.%, and strong carbide forming elements such as Cr, Mo, V, Nb, Ti, W and the like are abandoned, so that the generation of an alloy carbide precipitation phase is avoided, but potential Mn-rich alloy cementite and interface segregation of C elements exist. The strength of the alloy steel provided by the invention is not dependent on precipitation strengthening of carbide and interstitial solid solution strengthening of C atoms, but Cu-rich precipitated phase and NiAl precipitated phase are used as main strengthening sources; meanwhile, the delayed diffusion effect of Co element is utilized to avoid excessive coarsening of Cu-rich precipitated phase and NiAl precipitated phase at high temperature or during long-time heat preservation, the tempering softening resistance of the alloy steel is improved, the precipitation strengthening effect is ensured, and simultaneously, the high-temperature critical tempering of a two-phase region can be utilized to regulate and control the morphological distribution of reverse transformation austenite, so that the toughness of the alloy steel is improved; under the combined action of the elements, the ultra-low carbon alloy steel provided by the invention has higher strength and toughness even under the beneficial action of abandoning carbide precipitation.
The invention also provides a preparation method of the precipitation strengthening type ultra-low carbon alloy steel in the technical scheme, which comprises the following steps: smelting alloy raw materials according to the element proportion to obtain a casting blank; preparing the precipitation-strengthened ultra-low carbon alloy steel from the casting blank according to any one of modes 1-3; mode 1: rolling the casting blank and then carrying out ultra-fast cooling to obtain the precipitation-strengthened ultra-low carbon alloy steel; the rolling is rough rolling and finish rolling or warm rolling; mode 2: carrying out rough rolling and finish rolling on the casting blank, cooling to room temperature, and sequentially carrying out austenitizing treatment and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel; mode 3: and cooling the casting blank to room temperature after rough rolling and finish rolling, and sequentially carrying out austenitizing treatment, two-phase region critical tempering and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel. The specific rolling and heat treatment preparation method is shown in fig. 1.
The microstructure of the precipitation strengthening type ultra-low carbon alloy steel obtained by the preparation method provided by the invention is mainly carbide-free bainite or tempered martensite, and the distribution forms of a Cu-rich precipitation phase, a NiAl precipitation phase and reverse transformed austenite are regulated and controlled through a specific treatment process combination, so that the alloy steel keeps higher strength and toughness under the condition of no carbide. Meanwhile, the carbon equivalent is greatly reduced due to the ultra-low carbon, and the welding performance is improved.
Drawings
FIG. 1 is a flow chart of a preparation process of precipitation strengthening type ultra-low carbon alloy steel;
FIG. 2 is a hardness change curve of quenched precipitation-strengthened ultra-low carbon alloy steel from 1h of tempering at different temperatures and aging at 450 ℃ to 512 h;
FIG. 3 is a metallographic microstructure of a precipitation-strengthened ultra-low carbon alloy steel prepared in example 1;
FIG. 4 is an EBSD morphology of lath martensite in the precipitation-strengthened ultra-low carbon alloy steel prepared in example 2;
FIG. 5 is an APT three-dimensional spatial distribution diagram of a nano second phase in the precipitation-strengthened ultra-low carbon alloy steel prepared in example 2;
FIG. 6 is an EBSD orientation diagram of a dual-phase microstructure of a reversed transformed austenite-ferrite matrix in the precipitation-strengthened ultra-low carbon alloy steel prepared in example 3;
FIG. 7 is a HRTEM morphology of a nano second phase in the precipitation-strengthened ultra-low carbon alloy steel prepared in example 3.
Detailed Description
The invention provides precipitation strengthening type ultra-low carbon alloy steel which comprises the following element components in percentage by mass:
in the present invention, all the raw materials of the element components are commercially available products well known to those skilled in the art, unless otherwise specified.
The precipitation strengthening type ultra-low carbon alloy steel comprises 0.001-0.01% of C, preferably 0.005-0.008% by mass. In the invention, although the extremely low C content loses the beneficial effects of the interstitial solid solution strengthening and the related carbides, the problems of corresponding potential interface segregation, tempering embrittlement and the like are avoided, thereby ensuring the good toughness and plasticity of the alloy matrix; meanwhile, the carbon equivalent is greatly reduced, and the welding performance is improved.
According to the mass percentage, the precipitation strengthening type ultra-low carbon alloy steel provided by the invention comprises 0.5-1.2% of Si, and preferably 0.5-0.8%. In the invention, the Si mainly plays a role in solid solution strengthening and compensates for the strength reduction caused by low C to a certain extent; meanwhile, Si inhibits the growth and excessive coarsening of a Cu-rich precipitated phase and a NiAl precipitated phase, so that the Cu-rich precipitated phase and the NiAl precipitated phase are finer, and the strength is improved. However, the brittleness tendency of the alloy steel is increased due to excessive Si, and the content of Si is limited within the range, so that the alloy steel has good plasticity and toughness while the strength is improved.
According to the mass percentage, the precipitation strengthening type ultra-low carbon alloy steel provided by the invention comprises 1.2-3.5% of Mn, and preferably 2.8-3.5%. In the invention, the Mn mainly plays three roles, namely, a certain amount of solid solution strengthening is generated, and the strength of the alloy is improved; secondly, the method is beneficial to stabilizing the reversed transformed austenite phase, and particularly ensures that a certain amount of stable reversed transformed austenite is formed during critical tempering in a two-phase region under the condition of ultra-low carbon, thereby forming a wider process window for regulating and controlling the strength and toughness; thirdly, the Cu-rich precipitated phase is localized at the interface of the Cu-rich precipitated phase and the matrix, so that the growth of the Cu-rich precipitated phase is inhibited, and the strengthening effect of the Cu-rich precipitated phase is ensured.
According to the mass percentage, the precipitation strengthening type ultra-low carbon alloy steel provided by the invention comprises 2.0-5.0% of Ni, and preferably 3.5-5%. In the invention, the Ni is dissolved in the alpha-Fe matrix with BCC structure in a solid solution manner, so that the toughness of the alloy steel can be improved, and the premise of ensuring the low-temperature toughness of the alloy steel under different treatment process conditions is provided; meanwhile, Ni and Al form a NiAl phase to generate precipitation strengthening, and the strength of the alloy is further improved.
According to the mass percentage, the precipitation strengthening type alloy provided by the invention comprises 0.2-0.8% of Co, and preferably 0.5-0.6%. In the invention, the main function of Co is to inhibit the growth and excessive coarsening of Cu-rich precipitated phases and NiAl precipitated phases, so that the precipitated phases are finer and more dispersed, thereby ensuring that the strength of the Co-free alloy steel is higher than that of the Co-free alloy steel of the same category.
The precipitation strengthening alloy provided by the invention comprises 1.0-3.5% of Cu by mass percentage, and preferably 1-2%. In the invention, the Cu mainly forms a Cu-rich precipitated phase, and the Cu-rich precipitated phase contains a certain amount of Fe and a small amount of Ni, Al, Mn and other elements are segregated at the interface of the Cu-rich precipitated phase and a matrix; meanwhile, in the tempering process, a Cu-rich precipitated phase and a NiAl precipitated phase are separated out in an adjacent mode, and the strengthening effect far exceeding that of a single precipitated phase is achieved. In the present invention, the problem of "hot shortness" caused by Cu is to some extent alleviated or avoided by the high Ni content. In addition, Cu improves the corrosion resistance of alloy steel in atmosphere and seawater.
According to the mass percentage, the precipitation strengthening type ultra-low carbon alloy steel comprises 0.8-1.8% of Al, and preferably 1-1.5%. In the invention, the Al mainly forms a NiAl precipitated phase, and the content of the Al is limited in the range, so that the independently existing NiAl precipitated phase with a certain volume fraction can be formed, and the NiAl precipitated phase is not partially gathered near the interface of the Cu-rich precipitated phase and the matrix, and the co-precipitation of the two precipitated phases is formed to effectively improve the strength of the alloy steel.
According to the mass percentage, the precipitation strengthening type ultra-low carbon alloy steel comprises 0-0.005% of B, and preferably 0.002-0.005%. In the invention, B can form a lath martensite structure with a hierarchical structure under the condition of no strong carbide forming element, namely, the hardenability is increased, the number of interfaces such as laths and lath bundles of martensite is increased, the effective grain size of martensite is refined, and more effective nucleation positions are provided for a nano precipitated phase.
According to the mass percentage, the precipitation strengthening type ultra-low carbon alloy steel also comprises the balance of Fe and inevitable impurities. In the invention, the impurities comprise P and/or S, the mass percentage of P is preferably less than 0.015%, and the mass percentage of S is preferably less than 0.010%.
Under the combined action of the elements with specific contents, on the premise of abandoning the beneficial action of C and carbide in the alloy steel, a composite precipitated phase is formed by adding Ni, Cu and Al, and meanwhile, the size and distribution of a second phase are regulated and controlled by a small amount of Co, and the solid solution strengthening effect of alloy elements such as Si, Mn and the like and the effect of stable reverse transformation of Mn into austenite are added, so that the ultra-low carbon alloy steel has higher strength and toughness.
The invention adopts the design of ultra-low carbon and no strong carbide forming element components, and has two main advantages: firstly, the direct influence of C on welding performance is avoided, and then more austenite forming elements such as Ni, Mn and the like can be added to increase the content of reverse transformed austenite formed in the off-line heat treatment process, so that the low-temperature toughness is improved; secondly, the formation of high-temperature alloy carbide is avoided, and the deformation resistance of the alloy steel is further reduced to be beneficial to low-temperature rolling, so that more crystal defects are introduced, the formation of a nano precipitated phase in the rolling or phase change process is facilitated, and the manufacturing process window and the obdurability combination mode can be further widened. On the other hand, the precipitation-strengthened phase is mostly in a nano size and maintains a good coherent relationship with the ferrite matrix, and not excessively impairs toughness while imparting excellent strength to the alloy steel. The ultra-low carbon alloy steel without carbide forming elements has high strength and high toughness, can avoid the heat treatment before and after welding of relevant components such as ships, bridges, oil pipelines, low-temperature pressure vessels and the like, and further reduces the manufacturing cost.
The invention also provides a preparation method of the precipitation strengthening type ultra-low carbon alloy steel in the technical scheme, which comprises the following steps:
smelting alloy raw materials according to the element proportion to obtain a casting blank;
preparing the precipitation-strengthened ultra-low carbon alloy steel from the casting blank according to any one of modes 1-3;
mode 1: rolling the casting blank and then carrying out ultra-fast cooling to obtain the precipitation-strengthened ultra-low carbon alloy steel; the rolling is rough rolling and finish rolling or warm rolling;
mode 2: carrying out rough rolling and finish rolling on the casting blank, cooling to room temperature, and sequentially carrying out austenitizing treatment and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel;
mode 3: and cooling the casting blank to room temperature after rough rolling and finish rolling, and sequentially carrying out austenitizing treatment, two-phase region critical tempering and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel.
According to the invention, alloy raw materials are smelted according to the element proportion to obtain a casting blank. In the invention, the smelting technology preferably comprises the smelting technologies of ladle refining (EBT + LF) + Vacuum Degassing (VD) + Vacuum Casting (VC), and the like, can reduce the content of S, P and impurity elements such as non-metallic inclusions and the like in the alloy to the maximum extent, is a conventional steel smelting technology, and has no special limitation on the process parameters. The invention preferably adopts a continuous casting or die casting mode to cast to obtain a plate blank or a square blank, and rolling or forging processes are respectively applied to obtain alloy steel thick plates or forgings with different specifications.
After a casting blank is obtained, the casting blank is preferably reheated before rolling or forging, the reheating temperature is preferably 1050-1150 ℃, more preferably 1080-1100 ℃, and the temperature is slightly lower than that of common alloy steel due to no carbide forming elements so as to obtain a fine high-temperature austenite grain structure; the reheating heat preservation time is preferably 2-15 h, and more preferably 3-8 h (related to the specific casting blank size). The invention is reheated before rolling or forging, which not only facilitates subsequent rolling or forging, but also can further eliminate component segregation in the casting blank and improve the final mechanical property of the alloy steel.
In the invention, the rolling or forging has a cumulative compression ratio of 4-7, preferably 5-7, so as to eliminate potential casting defects. The forging process is a conventional die forging or free forging technology, the finish forging temperature can be as low as 580 ℃, and other process parameters are not specially limited. The rolling process is a conventional thick plate hot rolling technology and comprises rough rolling and finish rolling, wherein the initial rolling temperature of the rough rolling is 950-1150 ℃, the rolling temperature of the finish rolling can be as low as 580 ℃, the total accumulated reduction rate of the rough rolling and the finish rolling is not less than 62%, and other process parameters are not specially limited.
When the precipitation strengthening type ultra-low carbon alloy steel is prepared according to the mode 1, the deformation amount of warm rolling is preferably 16-40%, and more preferably 30-35%; the cooling rate of the ultra-fast cooling is preferably 15-51 ℃/s, and more preferably 15-25 ℃/s. According to the invention, a large amount of deformation defects can be introduced through warm rolling, nucleation and growth of second phase particles such as a Cu-rich precipitated phase and a NiAl precipitated phase at a dislocation or austenite-ferrite phase change interface are facilitated, and the strength of the alloy steel is improved by utilizing deformation strengthening and precipitation strengthening.
When the precipitation strengthening type ultra-low carbon alloy steel is prepared according to the mode 2, the rolling or forging process parameters are not specially limited, and the method is a conventional alloy steel rolling or forging technology; the austenitizing treatment, also referred to as austenitizing treatment, is aimed at (i) completely dissolving the latent second phase formed during rolling and (ii) obtaining complete high temperature austenite for quenching into a martensitic structure. In the invention, the austenitizing treatment temperature is preferably 810-890 ℃, and more preferably 810-850 ℃; the austenitizing treatment time is preferably 0.5-3 h (depending on the maximum interface size); the cooling method of the austenitizing treatment is preferably water cooling. In the invention, the austenitizing treatment can fully dissolve each element component in a gamma-Fe matrix, and simultaneously ensure complete austenitizing so as to obtain a martensite structure with solute atoms fully dissolved after quenching. In addition, under the condition of no carbide forming element, high-temperature austenite grains are easy to coarsen, and the invention adopts relatively low solid solution temperature to prevent the excessive growth of the austenite grains, thereby refining the final microstructure to ensure the strength of the alloy steel.
When the precipitation strengthening type ultra-low carbon alloy steel is prepared according to the mode 2, the tempering temperature is preferably 475-550 ℃, and more preferably 500-520 ℃; the tempering time is preferably 0.5-6 h, and more preferably 1-3 h. In the present invention, the alloy after the tempering treatment is preferably air-cooled to room temperature. In the invention, thanks to the prior austenitizing treatment, a nano Cu-rich precipitated phase and a nano NiAl precipitated phase are formed in the tempering process, the average size is 1.8-5 nm, the spacing is 1.5-6 nm, and the number density is 1023～1024m-3A rank. The ultra-low carbon alloy steel of the invention is endowed with high strength by the dispersed composite precipitated phase.
When the precipitation strengthening type ultra-low carbon alloy steel is prepared according to the mode 3, the rolling or forging process parameters are not specially limited, and the method is a conventional alloy steel rolling or forging technology; the austenitizing treatment and the tempering treatment are consistent with the method 2, and the temperature of the critical tempering treatment in the two-phase region is preferably 625-680 ℃, and more preferably 650-675 ℃; the critical tempering time of the two-phase region is preferably 0.5-2 h, and more preferably 1-1.5 h. Book (I)After the two-phase critical tempering, the two-phase critical tempering is preferably carried out, and then the two-phase critical tempering is preferably carried out by air cooling or water cooling to the room temperature, and more preferably carried out by water cooling to the room temperature. In the present invention, the purpose of the critical tempering in the two-phase region is: the reverse transformation austenite is promoted to nucleate at interfaces such as quenched martensite laths and prior austenite grain boundaries, and the volume fraction is preferably 5-25%, and more preferably 12-20%. The austenite phase with the FCC structure can 'purify' an alpha-Fe matrix by 'enriching' impurity elements such as S, P, can improve the whole plasticity by inducing plasticity through self phase transformation, and can improve the toughness by increasing the turning times of crack propagation, thereby endowing the ultra-low carbon alloy steel of the invention with high toughness, particularly low temperature toughness. On the other hand, because the critical tempering temperature of the two-phase region is higher, the formed nano Cu-rich precipitated phase and NiAl precipitated phase grow up continuously, the average size is 4-15 nm, the spacing is 8-50 nm, and the number density is 1022～1023m-3And rank, the strengthening effect is relatively low.
In the invention, the off-line heat treatment in the modes 2 and 3 is preferably performed according to the mode of the technical scheme, and the method is suitable for alloy steel thick plates or forgings, and the specific process parameters have a certain relation with the thickness of the thick plates and the maximum section thickness of the forgings.
In the invention, the precipitation-strengthened ultra-low carbon alloy steel prepared by the modes 1, 2 and 3 has mechanical properties, wherein when the yield strength is 700-1180 MPa, the tensile strength is 850-1250 MPa, the elongation can reach 10-20%, the impact energy at room temperature is 20-300J, and the impact energy at-80 ℃ is 8-250J.
The precipitation strengthening type ultra-low carbon alloy steel provided by the invention can be applied to the fields of ships, bridges, oil pipelines, low-temperature pressure containers and the like. The precipitation strengthening type ultra-low carbon alloy steel provided by the invention has good welding performance, can be directly welded without heat treatment before or after welding, and reduces the manufacturing cost.
The technical solutions provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of the present invention.
Example 1
The precipitation strengthening type ultra-low carbon alloy steel comprises the following components in percentage by mass: 0.008% C, 3.2% Mn, 0.8% Si, 4.8% Ni, 1.17% Cu, 1.05% Al, 0.589% Co, 0.002B, and the balance Fe.
The preparation method of the precipitation strengthening type ultra-low carbon alloy steel comprises the following steps:
(1) vacuum induction melting is adopted, casting is carried out to obtain a casting blank with the thickness of 180mm, then the casting blank is heated to 1050 ℃, and heat preservation is carried out for 3 hours;
(2) rolling the heated casting blank obtained in the step (1) in two stages, wherein the total compression ratio is 9; the initial rolling temperature of rough rolling is 980 ℃, the final rolling temperature is 870 ℃, and the total number of passes is 8; the finish rolling or warm rolling start temperature is 740 ℃, the finish rolling temperature is 586 ℃, and the total number of the rolling passes is 12;
(3) relaxing the hot rolled plate obtained in the step (2) for 15s, and cooling to room temperature at an ultra-fast cooling rate of 25 ℃/s to obtain the precipitation strengthening type ultra-low carbon alloy steel.
The room-temperature microstructure of the precipitation-strengthened ultra-low carbon alloy steel of this example is shown in FIG. 3.
In this embodiment, the precipitation-strengthened ultra-low carbon alloy steel has both improved strength and improved toughness while reducing the manufacturing cost, and has mechanical properties (transverse direction) as follows: the yield strength is 1020MPa, the tensile strength is 1078MPa, the elongation is 12.2 percent, and the impact energy at room temperature is 153J and the impact energy at minus 80 ℃ is 108J.
Example 2
The precipitation strengthening type ultra-low carbon alloy steel comprises the following components in percentage by mass: 0.008% C, 3.1% Mn, 1.0% Si, 4.9% Ni, 1.87% Cu, 1.45% Al, 0.463% Co, and the balance Fe.
The preparation method of the precipitation strengthening type ultra-low carbon alloy steel comprises the following steps:
(1) vacuum induction melting is adopted, casting is carried out to obtain a casting blank with the thickness of 180mm, then heating is carried out to 1080 ℃, and heat preservation is carried out for 3 hours;
(2) rolling the heated casting blank obtained in the step (1) in two stages, wherein the total compression ratio is 8; the initial rolling temperature of rough rolling is 980 ℃, and the final rolling temperature is 870 ℃; the initial rolling temperature of finish rolling is 840 ℃, the final rolling temperature is 750 ℃, and finally a hot rolled plate of 22mm is obtained, and the hot rolled plate is cooled in air at room temperature;
(3) re-heating the hot rolled plate obtained in the step (2) to 890 ℃ for austenitizing treatment for 1h, and then performing water quenching to room temperature; and tempering the thick plate subjected to water quenching at 500 ℃ for 1h to obtain the precipitation-strengthened ultra-low carbon alloy steel.
For comparison, the quenched thick plate in the step (3) is simultaneously tempered at different temperatures of 400-700 ℃ for 1 hour, and aged at 450 ℃ for 0.5-512 hours, so as to obtain hardness change curves under different conditions, as shown in fig. 2.
For comparison, when the 500 ℃ tempering treated sample in the step (3) is compared with the 450 ℃ undertempered sample and the 675 ℃ overtempered sample, the grain orientation and the Electron Back Scattering Diffraction (EBSD) morphology of the interface distribution are shown in FIG. 4, and the APT three-dimensional space reconfiguration graph of the distribution characteristics of the nano precipitated phases in the 450 ℃ tempering sample and the 500 ℃ tempering sample for 1h is shown in FIG. 5.
In this example, the precipitation-strengthened ultra-low carbon alloy steel has the following mechanical properties, with strength being preferred: the yield strength is 1180MPa, the tensile strength is 1229MPa, the elongation is 10.5 percent, and the impact energy at room temperature is 68J and the impact energy at minus 80 ℃ is 34J.
Example 3
The precipitation strengthening type ultra-low carbon alloy steel comprises the following components in percentage by mass: 0.008% C, 3.1% Mn, 1.0% Si, 4.9% Ni, 1.87% Cu, 1.45% Al, 0.463% Co, and the balance Fe.
The preparation method of the precipitation strengthening type ultra-low carbon alloy steel comprises the following steps:
(1) vacuum induction melting is adopted, casting is carried out to obtain a casting blank with the thickness of 180mm, then heating is carried out to 1080 ℃, and heat preservation is carried out for 3 hours;
(2) rolling the heated casting blank obtained in the step (1) in two stages, wherein the total compression ratio is 8; the initial rolling temperature of rough rolling is 980 ℃, and the final rolling temperature is 870 ℃; the initial rolling temperature of finish rolling is 840 ℃, and the final rolling temperature is 750 ℃. Finally obtaining a hot rolled plate with the thickness of 22mm, and air-cooling the hot rolled plate at room temperature;
(3) re-heating the hot rolled plate obtained in the step (2) to 890 ℃ for austenitizing treatment for 1h, and then performing water quenching to room temperature; and carrying out critical tempering on the thick plate subjected to water quenching for 1h in a two-phase region at 675 ℃, and then carrying out tempering treatment for 1h at 500 ℃ to obtain the precipitation-strengthened ultra-low carbon alloy steel.
In the precipitation-strengthened ultra-low carbon alloy steel, the toughening phase is reverse transformed austenite, and the form distribution is shown in fig. 6; the strengthening phase is a Cu-rich precipitated phase, and the high-resolution morphology of the TEM is shown in FIG. 7.
In this embodiment, the precipitation-strengthened ultra-low carbon alloy steel has the following mechanical properties: the yield strength is 796MPa, the tensile strength is 907MPa, the elongation is 16.2 percent, and the impact energy at room temperature is 264J and the impact energy at minus 80 ℃ is 225J.
Fig. 1 shows three preparation methods of three embodiments of precipitation-strengthened ultra-low carbon alloy steel respectively corresponding to the claims.
FIG. 2 is a graph showing the changes in temper and age hardness of the precipitation-strengthened ultra-low carbon alloy steel according to example 2 of the present invention, and it can be seen that the alloy steel has a typical precipitation strengthening effect.
FIG. 3 is a microstructure of controlled rolling and controlled cooling state according to example 1 of precipitation-strengthened ultra-low carbon alloy steel of the present invention, and it can be seen that: the rolling microstructure is mainly martensite and carbide-free bainite, and has anisotropic characteristics. The second phase particles such as Cu-rich precipitation phase and the like formed in the rolling deformation and austenite-ferrite phase transformation process can further improve the alloy strength.
FIG. 4 is a characteristic diagram of EBSD patterns at 500 ℃ and under-aged 450 ℃ and over-aged 650 ℃ in example 2 of the precipitation-strengthened ultra-low carbon alloy steel according to the present invention, and shows that: the microstructure of the precipitation strengthening type ultra-low carbon alloy steel has a lath martensite morphology with a hierarchical structure, a tiny martensite plate block interface is displayed, the equivalent grain size of a matrix is represented, wherein a crystal orientation diagram shows different martensite packets, and the martensite blocks have similar crystal orientations in the same packet; the interface distribution diagram distinguishes interfaces with different angles, mainly a large-angle prior austenite crystal boundary and a small-angle martensite lath or block interface. It is noteworthy that even when aged at high temperature 675 deg.C, the lath morphology was still present and the tendency to recrystallize was reduced, showing that this structure had a higher thermal stability, which is not related to the retarded growth of the nano-precipitated phase and the addition of Co element. It should be noted that, since the C content is extremely low, the martensitic transformation is weak in lattice distortion, the dislocation density corresponding thereto is low, and the dislocation density is sharply reduced with the increase in the tempering temperature, and thus the contribution to the strength is relatively weak, but the fine interface structure increases the energy consumption at the time of crack propagation, and thus contributes to the improvement of toughness and plasticity.
TABLE 1 size and number density of precipitated phases in the precipitation-strengthened alloy obtained in example 2
FIG. 5 is an APT atomic reconfiguration diagram of 500 ℃ and underaged 450 ℃ according to example 2 of the precipitation-strengthened ultra-low carbon alloy steel of the present invention, which shows that: the precipitation strengthening type ultra-low carbon alloy steel forms Cu-rich clusters, NiAl clusters and Mn-rich nano cementite at 450 ℃, particularly at crystal defect positions such as crystal boundary and the like; and a Cu-rich precipitated phase and a NiAl precipitated phase with a certain crystal structure are formed at 500 ℃, and are uniformly dispersed in the tempered martensite matrix. Table 1 compares the size and the number density of the precipitated phases under two conditions, and it can be seen that equivalent radii of the Cu-rich precipitated phase and the NiAl precipitated phase prepared at 500 ℃ and 450 ℃ are not much different, and the number density is increased by one order of magnitude, which indicates that the precipitated phase in the precipitation-strengthened ultra-low carbon alloy steel provided by the present invention has a good anti-coarsening capability, and this is mainly benefited by the beneficial effect of the Co element. Meanwhile, adjacent precipitation of a Cu-rich precipitated phase and a NiAl precipitated phase or segregation of Ni, Al and Mn at the interface of the Cu-rich precipitated phase reduces corresponding interface strain energy and also hinders further growth of the precipitated phase. The co-precipitated nano precipitated phase with high number density and dispersed distribution and the coherent relation with the matrix can not only produce strong precipitation strengthening, but also relieve the stress concentration at the tip of the crack to a certain extent, and are beneficial to improving the toughness.
Fig. 6 is an EBSD crystal orientation diagram of a dual-phase microstructure of a reversed transformed austenite-ferrite matrix in the precipitation-strengthened ultra-low carbon alloy steel prepared in example 3 of the present invention, which shows that: a large amount of fine, dispersed, thin-film reverse-transformed austenite is formed along the martensite lath interface and has the same crystal orientation within the same prior austenite grain. In addition, the morphological distribution of the reversed austenite is different among the prior austenite grains, which is related to whether it is parallel to the precipitation interface. Actually, these reverse transformed austenite is often in the form of a thin film (in the form of a bulk at the prior austenite grain boundary), contains high content of austenite forming elements such as Ni and Mn, has high stability, and can generate transformation-induced plasticity under an external load, and extend crack propagation paths, thereby increasing plasticity and toughness.
Fig. 7 is a high-resolution electron microscopic morphology of a Cu-rich precipitate phase in the precipitation-strengthened ultra-low carbon alloy steel prepared in example 3 of the present invention, and it can be seen that: compared with the nano precipitated phase (shown in fig. 5) dispersed in the embodiment 2, the precipitated phase grows and coarsens in the critical tempering process of the two-phase region, the strengthening effect is greatly reduced, and the overall toughness and plasticity are improved. In addition, such coarsened large size Cu-rich precipitate phase with FCC structure may itself be beneficial for toughness or plasticity enhancement, but this is still to be further confirmed.
Although the present invention has been described in detail with reference to the above embodiments, it is only a part of the embodiments of the present invention, not all of the embodiments, and other embodiments can be obtained without inventive step according to the embodiments, and the embodiments are within the scope of the present invention.
Claims (10)
1. A precipitation strengthening type ultra-low carbon alloy steel comprises the following element components in percentage by mass:
2. the method for preparing the precipitation-strengthened ultra-low carbon alloy steel as set forth in claim 1, comprising the steps of:
smelting alloy raw materials according to the element proportion to obtain a casting blank;
preparing the precipitation-strengthened ultra-low carbon alloy steel from the casting blank according to any one of modes 1-3;
mode 1: rolling the casting blank and then carrying out ultra-fast cooling to obtain the precipitation-strengthened ultra-low carbon alloy steel; the rolling is rough rolling and finish rolling or warm rolling;
mode 2: carrying out rough rolling and finish rolling on the casting blank, cooling to room temperature, and sequentially carrying out austenitizing treatment and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel;
mode 3: and cooling the casting blank to room temperature after rough rolling and finish rolling, and sequentially carrying out austenitizing treatment, two-phase region critical tempering and tempering treatment on the rolled plate blank to obtain the precipitation-strengthened ultra-low carbon alloy steel.
3. The production method according to claim 2, wherein the temperature of the finish rolling or the warm rolling in the mode 1 is 580 to 690 ℃, the deformation amount of the finish rolling or the warm rolling is 16 to 40%, and the cooling rate is 15 to 51 ℃/s.
4. The method according to claim 2, wherein the austenitizing treatment in the modes 2 and 3 is performed at a temperature of 810 to 890 ℃ for 0.5 to 3 hours.
5. The method according to claim 2, wherein the tempering treatment in the modes 2 and 3 is carried out at 475 to 550 ℃ for 0.5 to 6 hours.
6. The method according to claim 2, wherein the critical tempering treatment in the two-phase region in the mode 3 is performed at 625-680 ℃ for 0.5-2 hours.
7. The precipitation-strengthened ultra-low carbon alloy steel according to claim 2, wherein the matrix structure is ferrite, and the average grain size is 2 to 20 μm.
8. The precipitation-strengthened ultra-low carbon alloy steel obtained by the preparation method according to claim 2, wherein the strengthening phases in the microstructure are a Cu-rich precipitation phase and a NiAl precipitation phase which are in a nano-coherent structure, the average size is 1.8-15 nm, the spacing is 1.5-50 nm, and the number density is 1022～1024m-3A rank.
9. The precipitation-strengthened ultra-low carbon alloy steel obtained by the preparation method according to claim 2, wherein the toughening phase in the microstructure is an austenite phase, is mainly distributed at interfaces such as martensite laths or the like or prior austenite grain boundaries, and has a volume fraction of 5-25%.
10. The precipitation-strengthened ultra-low carbon alloy steel obtained by the preparation method of claim 2 is characterized by having a yield strength of 700-1180 MPa, a tensile strength of 850-1250 MPa, an elongation of 10-20%, a room-temperature impact energy of 20-300J, and an impact energy of 8-250J at-80 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011156140.XA CN112267075B (en) | 2020-10-26 | 2020-10-26 | Precipitation type reinforced alloy and preparation method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011156140.XA CN112267075B (en) | 2020-10-26 | 2020-10-26 | Precipitation type reinforced alloy and preparation method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112267075A true CN112267075A (en) | 2021-01-26 |
| CN112267075B CN112267075B (en) | 2022-04-26 |
Family
ID=74341687
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011156140.XA Active CN112267075B (en) | 2020-10-26 | 2020-10-26 | Precipitation type reinforced alloy and preparation method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112267075B (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107699803A (en) * | 2017-09-29 | 2018-02-16 | 上海交通大学 | A kind of Ultra-low carbon cryogenic steel and its Technology for Heating Processing |
-
2020
- 2020-10-26 CN CN202011156140.XA patent/CN112267075B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107699803A (en) * | 2017-09-29 | 2018-02-16 | 上海交通大学 | A kind of Ultra-low carbon cryogenic steel and its Technology for Heating Processing |
Non-Patent Citations (2)
| Title |
|---|
| 李云凯，薛云飞编著: "《金属材料学》", 31 January 2019, 北京理工大学出版社 * |
| 西安交通大学锅炉教研室: "《锅炉钢材与制造工艺学 上》", 31 August 1977 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112267075B (en) | 2022-04-26 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2021169941A1 (en) | Chain steel for use in mine and manufacturing method therefor | |
| CN111748739B (en) | Heat-resistant spring steel with tensile strength of more than 2100MPa and production method thereof | |
| CN111218618B (en) | Hydrogen embrittlement resistant, high strength and toughness stainless steel bar for fastener and method of making same | |
| WO2020238851A1 (en) | Steel, wire rod and manufacturing method of wire rod | |
| CN105821301A (en) | 800MPa-level hot-rolled high strength chambering steel and production method thereof | |
| CN113249645B (en) | High-ductility and ultrahigh-strength ductile steel and preparation method thereof | |
| CN114107821B (en) | High-toughness ultrahigh-strength steel and manufacturing method thereof | |
| CN101586217B (en) | Low-cost and ultra-high strength and toughness martensite steel and manufacturing method thereof | |
| CN109161789B (en) | Low-temperature steel plate for LPG ship and production method thereof | |
| CN111809114B (en) | Plastic die steel with excellent high-temperature strength and preparation method thereof | |
| CN113774280A (en) | 2400 MPa-grade high-ductility high-corrosion-resistance maraging stainless steel and preparation method thereof | |
| CN113737090B (en) | High-strength and high-toughness alloy structural steel and preparation method thereof | |
| CN111748737B (en) | Easily-welded ultrahigh-strength steel with cold crack sensitivity coefficient less than or equal to 0.25 and production method thereof | |
| CN110863143B (en) | Manufacturing method of 960MPa grade ultra-high strength steel with excellent low temperature toughness | |
| CN109136761B (en) | 980 MPa-grade high-ductility low-density austenitic steel for automobiles and preparation method thereof | |
| CN115572901B (en) | 630 MPa-grade high-tempering-stability low-carbon low-alloy steel plate and manufacturing method thereof | |
| CN113166901A (en) | Chromium-molybdenum steel plate with excellent creep strength and preparation method thereof | |
| CN112267075B (en) | Precipitation type reinforced alloy and preparation method thereof | |
| CN111979393A (en) | Hot-rolled high-strength steel plate with excellent low-temperature toughness and preparation method thereof | |
| CN114250424B (en) | Ni-free steel for low-temperature pressure vessel and manufacturing method thereof | |
| CN111647803B (en) | Copper-containing high-strength steel and preparation method thereof | |
| CN111218616B (en) | Low-temperature-resistant high-toughness high-strength low-alloy round steel and preparation method thereof | |
| CN115181894A (en) | 590 MPa-grade high-formability hot-galvanized dual-phase steel and rapid heat treatment hot galvanizing manufacturing method | |
| CN111979474A (en) | Hot continuous rolling fine grain bainite steel plate and preparation method thereof | |
| CN115354219B (en) | SA516Gr70 steel plate with excellent high-temperature strength at 200-400 ℃ and manufacturing method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |