CN112029965A

CN112029965A - Novel super 13Cr annealing method

Info

Publication number: CN112029965A
Application number: CN202010802032.9A
Authority: CN
Inventors: 宋康; 陈炳华; 陈松林
Original assignee: Jiangsu Changbao Pls Steel Tube Co ltd
Current assignee: Jiangsu Changbao Pls Steel Tube Co ltd
Priority date: 2020-08-11
Filing date: 2020-08-11
Publication date: 2020-12-04

Abstract

The embodiment of the invention discloses a novel super 13Cr annealing method in the technical field of annealing processing. The super 13Cr annealing method comprises the following steps: s1, performing normalizing heating treatment on the super 13Cr, performing constant-temperature heat preservation treatment, and then performing air cooling rapid cooling treatment; and S2, after the steel is cooled, raising the temperature again to carry out tempering heat preservation treatment, and then carrying out air cooling treatment. According to the super 13Cr annealing process, the normalizing and tempering treatment process is utilized, and the heating temperature and the heat preservation time of the heat treatment are controlled, so that the hardness of the super 13Cr can be reduced, the subsequent cold rolling is easier to realize, the cold rolling defects are reduced, the process flow required by annealing is shortened, the original complex annealing operation is simpler and more convenient to operate, and the comprehensive performance of steel is effectively improved.

Description

Novel super 13Cr annealing method

Technical Field

The embodiment of the invention relates to the technical field of annealing processing, in particular to a novel super 13Cr annealing method.

Background

Annealing is a heat treatment process for metals, which refers to slowly heating the metal to a certain temperature, holding for a sufficient time, and then cooling at a suitable rate. The purpose is to reduce hardness and improve machinability; the residual stress is eliminated, the size is stabilized, and the deformation and crack tendency is reduced; refining grains, adjusting the structure and eliminating the structure defects. Specifically, annealing is a heat treatment process for materials, including metallic materials and non-metallic materials. And the annealing purpose of the new material is different from that of the traditional metal annealing. One of the most important process parameters for annealing is the maximum heating temperature (annealing temperature), and the annealing heating temperature for most alloys is chosen based on the phase diagram of the alloy system, e.g., carbon steels based on the iron-carbon equilibrium diagram. The annealing temperature of each steel (including carbon steel and alloy steel) is at a temperature of Ac3 or more and Ac1 or less for each steel type depending on the specific purpose of annealing. The annealing temperature of each nonferrous alloy is a temperature not higher than the solidus temperature, not lower than the solidus temperature, or not higher than the solidus temperature of each alloy. The super 13Cr comprises bar materials and pipe materials, is mainly used for OCTG pipelines, shells and well completion underground equipment, and has the chemical composition of less than 0.03 percent of carbon; silicon is less than 0.50%; manganese is less than 0.50%; phosphorus is less than 0.02%; less than 0.005% of sulfur; 11.50-13.50 parts of chromium; 4.50-6.50 of nickel; 1.50-3.00% of molybdenum; 0.01 to 0.50 of titanium; 0.10-0.50 of vanadium; the balance of iron.

The traditional super 13Cr annealing process comprises the following steps:

	temperature/. degree.C	Holding time/min	Cooling method
				Primary annealing	860	50min	Air cooling
Secondary annealing	720	50min	Air cooling
				Triple annealing	720	50min	Air cooling

The annealing process cannot effectively reduce the hardness of the super 13Cr in the secondary annealing, is difficult to cold roll, sometimes needs three times of annealing and has low efficiency. The annealing times are large, and the cost consumption is increased.

Based on the above, the invention designs a novel super 13Cr annealing method to solve the above problems.

Disclosure of Invention

The embodiment of the invention provides a novel super 13Cr annealing method, which aims to solve the technical problems in the background art.

The embodiment of the invention provides a novel super 13Cr annealing method. In one possible embodiment, the method comprises the following steps:

s1, performing normalizing heating treatment on the super 13Cr, performing constant-temperature heat preservation treatment, and then performing air cooling rapid cooling treatment;

and S2, after the steel is cooled, raising the temperature again to carry out tempering heat preservation treatment, and then carrying out air cooling treatment.

The embodiment of the invention provides a novel super 13Cr annealing method. In one possible approach, the normalizing control temperature range in the S1 is 980-.

The embodiment of the invention provides a novel super 13Cr annealing method. In a feasible scheme, the normalizing and heat preserving control time range in the S1 is 30-50 min.

The embodiment of the invention provides a novel super 13Cr annealing method. In one possible embodiment, the tempering control temperature range in S2 is 710-.

The embodiment of the invention provides a novel super 13Cr annealing method. In a feasible scheme, the tempering heat preservation time in the S2 is 80-90 min.

Based on the scheme, the super 13Cr annealing process disclosed by the invention utilizes the normalizing and tempering treatment process and controls the heating temperature and the heat preservation time of the heat treatment, so that the hardness of the super 13Cr can be reduced, the subsequent cold rolling is easier to realize, the cold rolling defects are reduced, the process flow required by annealing is shortened, the original complex annealing operation is simpler and more convenient to operate, and the comprehensive performance of steel is effectively improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a graph of the temperature of a heat treatment according to the present invention as a function of time;

FIG. 2 is a table showing temperature control and holding time control during the heat treatment of the present invention;

FIG. 3 is a table showing temperature control and holding time control in one embodiment of the heat treatment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," and the like are used in the indicated orientations and positional relationships based on the drawings for convenience in describing and simplifying the description, but do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the invention.

In the present invention, unless otherwise specifically stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication connection; either directly or indirectly through intervening media, either internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The technical solution of the present invention will be described in detail below with specific examples. The following several specific embodiments may be combined with each other, and details of the same or similar concepts or processes may not be repeated in some embodiments.

FIGS. 1-2 illustrate a novel super 13Cr annealing method according to a first embodiment of the present invention, the super 13Cr annealing method according to the present embodiment; the method comprises the following steps:

Through the contents, the super 13Cr annealing process adopts a two-section heat treatment process, namely, the super 13Cr steel raw material is subjected to normalizing and tempering treatment, and the traditional process adopts an annealing process for at least three times aiming at the super 13Cr annealing process, namely, the annealing process is subjected to heating and temperature rise for more than three times and air cooling treatment after heat preservation time is controlled, so that the comprehensive performance of the steel is reduced after continuous annealing treatment for more times, cold rolling is difficult to perform and the processing cost is consumed very much, but the heat treatment times of the annealing process adopted by the invention are obviously reduced, and the processing cost can be reduced, the comprehensive performance can be ensured, the cost is reduced and the effect is increased by reducing the heat preservation times; according to the material characteristics of the super 13Cr, the content of Cr and Ni in the super 13Cr is higher, the carbon affinity of Cr is stronger, chromium-containing carbide is easy to form, the carbide crystal grain is small, the hardness and the wear resistance are very high, the subsequent processing is not facilitated, and by utilizing the super Cr annealing process, the chemical bond between chromium and carbon can be destroyed in a larger range, so that the hardness of the super Cr is reduced, and the performance is more stable; in the implementation process of the invention, the super 13Cr steel is subjected to normalizing high-temperature heating treatment to eliminate the netlike cementite, the heat preservation time is controlled to ensure that the flaky cementite in the 13Cr steel is spontaneously converted into the granular cementite, the internal stress of the steel structure is also eliminated, the size is stabilized, the deformation is reduced, and the heat-preserved steel is rapidly cooled by utilizing an air cooling mode, but in the traditional annealing process, the elimination work of the netlike cementite cannot be carried out on the steel with the carbon content of less than 0.25X, the cutting processing performance cannot be well changed, the normal annealing period is longer, the operation is complicated, and time and labor are wasted; after the normalizing air cooling is finished, the steel piece is tempered, namely the steel is heated to be below the austenite transformation temperature, and the heat preservation time is controlled and then air cooling is carried out, compared with the traditional annealing process, the mode can lead the steel structure to tend to be stable, lead the brittleness of the steel to be reduced, improve the toughness and plasticity, eliminate or reduce the quenching stress, prevent the steel from deforming and cracking, and further improve the comprehensive performance of the super 13 Cr.

Optionally, in this embodiment, the normalizing control temperature range in S1 is 980-1000 ℃. It is worth noting that, in the embodiment, the temperature range of the normalizing control is higher than the traditional annealing temperature, so that the reticular cementite in the steel can be well eliminated, and compared with the traditional annealing process, the process cycle is shortened due to the increase of the temperature, and the operation is convenient.

In addition, the normalizing heat preservation control time range in the S1 is 30-50min, and the reduction or elimination of the internal stress of the steel is realized by controlling the heat preservation time in the normalizing process.

More specifically, the tempering control temperature range in S2 is 710-750 ℃, which is similar to the conventional secondary or tertiary annealing control temperature, but the structure of the steel structure tends to be stable by tempering, the quenching profit is eliminated, the steel is not easy to deform or crack, and the cutting processability of the 13Cr steel can be improved by the high-temperature tempering.

Further, the tempering heat preservation control time in the S2 is 80-90min, and the heat preservation time in the tempering process is controlled, so that the conversion rate of the sheet cementite to the granular cementite can be conveniently improved, and the reduction or elimination of the internal stress of the steel can be further realized.

In the implementation process of the invention:

as shown in fig. 3, the normalizing temperature can be controlled to be 980 ℃, the normalizing heat preservation time is controlled to be 33min, then the tempering treatment at 720 ℃ is carried out after air cooling, and the tempering heat preservation time is controlled to be 86min, and then the air cooling treatment is carried out; after the control of the heating temperature and the heat preservation time, the hardness of the super 13Cr steel after modulation annealing is less than or equal to 26 HRC.

In the present invention, unless otherwise explicitly specified or limited, the first feature "on" or "under" the second feature may be directly contacting the first feature and the second feature or indirectly contacting the first feature and the second feature through an intermediate.

Also, a first feature "on," "above," and "over" a second feature may mean that the first feature is directly above or obliquely above the second feature, or that only the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lower level than the second feature.

In the description herein, reference to the description of the term "one embodiment," "some embodiments," "an example," "a specific example" or "some examples," or the like, means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A novel super 13Cr annealing method is characterized by comprising the following steps:

2. The novel super 13Cr annealing method as claimed in claim 1, wherein the normalizing control temperature in S1 is in the range of 980-1000 ℃.

3. The novel annealing method of super 13Cr according to claim 1, wherein the normalizing and holding time in S1 is controlled within 30-50 min.

4. The novel annealing method of super 13Cr as claimed in claim 1, wherein the tempering control temperature in S2 is 710-750 ℃.

5. The novel annealing method of super 13Cr according to claim 1, wherein the tempering holding time in S2 is 80-90 min.