CN110732605B - Stainless steel seal head hot forming method - Google Patents
Stainless steel seal head hot forming method Download PDFInfo
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- CN110732605B CN110732605B CN201911011534.3A CN201911011534A CN110732605B CN 110732605 B CN110732605 B CN 110732605B CN 201911011534 A CN201911011534 A CN 201911011534A CN 110732605 B CN110732605 B CN 110732605B
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- stainless steel
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- forming
- heat preservation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D51/00—Making hollow objects
- B21D51/16—Making hollow objects characterised by the use of the objects
- B21D51/38—Making inlet or outlet arrangements of cans, tins, baths, bottles, or other vessels; Making can ends; Making closures
- B21D51/44—Making closures, e.g. caps
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
- B21D22/02—Stamping using rigid devices or tools
- B21D22/022—Stamping using rigid devices or tools by heating the blank or stamping associated with heat treatment
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- 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
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
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- 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
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
The invention provides a stainless steel end socket hot forming method, which comprises the steps of placing stainless steel in a heating furnace at normal temperature, heating the stainless steel to 400 ℃ along with the furnace, then continuously heating the stainless steel to 900-950 ℃ at a heating speed of less than or equal to 150 ℃/h, and carrying out heat preservation treatment to obtain the stainless steel after stabilization treatment; and (3) under the temperature of 950-750 ℃, carrying out press forming on the stainless steel after the stabilization treatment, and cooling to obtain the stainless steel end socket. The method omits a common solid solution treatment process, can directly carry out one-time press forming or multiple-time press forming only by one-time heating treatment, has simple process, firstly separates out harmful elements in the crystal, then carries out heat preservation treatment to diffuse rich chromium in the crystal to eliminate poor chromium in the crystal, avoids the occurrence of poor chromium in the crystal again in a sensitized area during the forming process and after the forming, can reach the requirements of the mechanical property and the corrosion resistance of the product without solid solution, can greatly shorten the hot forming time and reduce the energy consumption, and is particularly suitable for the forming of the thin-wall large-diameter end socket.
Description
Technical Field
The invention relates to the field of pressure vessel equipment, in particular to a stainless steel seal head hot forming method.
Background
The stainless steel end socket is a product for plugging stainless steel pipelines. The product is used as a container after the pipeline is finished or two end sockets are welded at two ends of a section of circular tube. Similar products include blind plates, pipe caps, plugs and the like. Generally, the stainless steel seal head needs to be manufactured by adopting a hot forming process. Practice has shown that thermal and structural stresses occur during heat treatment of any workpiece, provided that there is a phase change. The thermal stress alone produced a stainless steel seal prior to the tissue transformation. In the aspect of end socket forming, particularly in the aspect of manufacturing an end socket forging of a water chamber of an evaporator with the greatest difficulty, a stainless steel forging for manufacturing the end socket generally needs to be subjected to solution treatment so as to meet the performance requirement of the stainless steel forging.
The quenching cooling is generally carried out by soaking in water. In order to ensure the uniformity of the heating temperature, an annular heating furnace is recommended to be used for heating, and the source is gas or electric energy. As shown in figure 1, when the furnace temperature is higher than 600 ℃, the stainless steel forging is generally placed in a heat treatment furnace cavity, the temperature is rapidly raised to 1040-1150 ℃ for heat preservation, then air cooling is rapidly carried out, solution treatment is carried out after the air cooling is finished, wherein the temperature is rapidly raised to 1050-1150 ℃ for heat preservation during solution treatment, and finally water cooling is carried out to finish the solution treatment.
The process has the advantages that the temperature control precision of the electric heating annular furnace is higher, the heat preservation precision can reach +/-5 ℃, the forming range is large, the process is not limited by the thickness, and the magnetic phase generation and the hardness increase caused by cold forging are avoided. The defects are higher operation cost, long forming time, high temperature, serious surface oxidation, easily-caused coarse grains, incapability of recovering through heat treatment due to performance reduction, more forming processes and large workload of deformation and renovation. Especially, when the thin-wall large-diameter stainless steel end socket is manufactured, the deformation is particularly prominent.
Disclosure of Invention
Accordingly, the present invention is directed to a method for hot forming a stainless steel end cap, so as to solve the above-mentioned problems.
Therefore, the technical scheme provided by the invention is as follows: a stainless steel end cap thermoforming method comprises the following steps:
placing the stainless steel in a heating furnace at normal temperature for stabilizing treatment, heating the stainless steel to 400 ℃ along with the furnace, then continuously heating the stainless steel to 900-950 ℃ at the heating speed of less than or equal to 150 ℃/h, and carrying out heat preservation treatment to obtain the stabilized stainless steel;
and (3) carrying out hot pressing treatment on the stabilized stainless steel at the temperature of 950-750 ℃, carrying out press forming on the stabilized stainless steel, and cooling to obtain the stainless steel end socket.
Based on the above, in the stabilizing treatment step, when the thickness of the stainless steel is less than 60mm, the heat preservation treatment time is 120min to 180 min.
Based on the above, in the stabilizing treatment step, when the thickness of the stainless steel is more than 60mm, the calculation formula of the soaking treatment time is (120+ (material thickness-60) × 2), and the unit of the soaking treatment time is minutes.
Based on the above, in the hot pressing step, after the stabilizing treatment, the stainless steel is subjected to press forming treatment, when the thickness of the stabilizing treated stainless steel is less than 30mm, air cooling treatment is adopted, when the thickness of the stabilizing treated stainless steel is 30 mm-60 mm, spray cooling is adopted, and when the thickness of the stabilizing treated stainless steel is more than 60mm, water cooling treatment is adopted.
Based on the above, the stainless steel is 304 austenitic stainless steel or 316 austenitic stainless steel.
Wherein, the stainless steel end cap is put into the front plate surface of the furnace to clean impurities, oil stains and the like on the surface, the surface is ensured to be clean, special anti-oxidation coating for stainless steel is coated, the furnace door is opened, the stainless steel end cap plate is put in, a thermocouple is contacted with the surface of a product to directly measure the surface temperature of the product, the process curve takes the surface temperature of the product as the standard, a heating furnace is carried out in an electric furnace or a natural gas furnace with good sealing performance, the atmosphere in the furnace is micro-oxidation atmosphere, and the content of sulfur in the natural gas is less than 0.57g/m3。
The stainless steel end socket hot forming method provided by the invention omits a common solid solution treatment process for preparing the stainless steel end socket, can directly perform one-time press forming or multiple-time press forming only by one-time heating treatment, and has simple process. Specifically, the stainless steel end enclosure hot forming method comprises the steps of firstly separating out harmful elements in the crystal at a temperature raising section at a sensitization temperature, then diffusing chromium-rich in the crystal to the crystal space through heat preservation to eliminate intergranular chromium depletion, and finally adopting one-time press forming or multiple-time press forming, so that intergranular chromium depletion in a sensitization area is avoided during and after forming, the forming process is better mastered and implemented, meanwhile, a series of problems of deformation, energy consumption, surface oxidation and the like caused by secondary solution treatment are avoided, the hot forming time of the stainless steel end enclosure is half less than that of hot forming time needing solution treatment on the premise that the mechanical property and the corrosion resistance of the stainless steel meet the standard, the consumed time is short, and meanwhile, the hot forming temperature is lower than the solidification temperature, the requirement on equipment is low, the energy consumption can be greatly reduced, and the enterprise cost is reduced.
More importantly, the stainless steel forming method provided by the invention can carry out hot press forming by only adopting one-time heat treatment, and can effectively avoid the defects of reduced mechanical and corrosion resistance caused by increased hardness, increased ferrite content and increased internal stress after cold forming of austenitic stainless steel. The heating process is suitable for austenitic stainless steel products with different thicknesses, can meet the requirements of mechanical property and corrosion resistance of the products without solid solution, and is particularly suitable for forming thin-wall large-diameter end sockets.
Drawings
FIG. 1 is a graph of a quenching and high temperature tempering process of a conventional stainless steel forging.
Fig. 2 is a process diagram of the stainless steel end cap hot forming method provided by the invention.
Detailed Description
The technical solution of the present invention is further described in detail by the following embodiments.
The embodiment of the invention provides a stainless steel seal head hot forming method, as shown in fig. 2, comprising the following steps:
placing the stainless steel in a heating furnace at normal temperature for stabilizing treatment, heating the stainless steel to 400 ℃ along with the furnace, then continuously heating the stainless steel to 900-950 ℃ at the heating speed of less than or equal to 150 ℃/h, carrying out heat preservation treatment, fixing carbon on crystal boundaries by using chromium, supplementing chromium in the crystals to the crystal boundaries, eliminating intergranular chromium depletion, and obtaining the stabilized stainless steel;
and (3) carrying out hot pressing treatment on the stabilized stainless steel at the temperature of 950-750 ℃, carrying out press forming on the stabilized stainless steel, and cooling to obtain the stainless steel end socket.
Wherein in the stabilizing treatment step, when the thickness of the stainless steel is less than 60mm, the heat preservation treatment time is 120-180 min; when the thickness of the stainless steel is more than 60mm, the calculation formula of the heat preservation treatment time is (120+ (material thickness-60) × 2), and the unit of the heat preservation treatment time is minutes.
In the hot pressing step, after the stabilized stainless steel is subjected to press forming treatment, air cooling treatment is adopted when the thickness of the stabilized stainless steel is less than 30mm, spray cooling is adopted when the thickness of the stabilized stainless steel is 30-60 mm, and water cooling is adopted when the thickness of the stabilized stainless steel is more than 60 mm.
The stainless steel is 304 austenitic stainless steel or 316 austenitic stainless steel.
The following examples further illustrate the technical aspects of the present invention by changing the stabilization temperature, holding time, cooling method, and the like in the above-described manner. The parameters used in the examples are shown in table 1.
TABLE 1 parameter tables used in the examples of the present invention
The performance of the stainless steels treated in examples 1 to 8 was examined.
1. Chemical composition detection test
Chemical components of the stainless steel before and after being treated in the examples 1-8 are detected by adopting a detection method of national standard GB/T20125-2006, and detection results are shown in Table 2.
Table 2 examples chemical composition (wt%) of stainless steel before and after treatment
As can be seen from table 2: the chemical compositions of the 304L and 316L austenitic stainless steels after the treatment of the embodiment of the invention are not changed greatly before and after the treatment, so that the chemical compositions of the austenitic stainless steels are basically not influenced by the stainless steel seal head hot forming method provided by the invention.
2. Mechanical Property test
Comparative example 1 sample: the same original material 304L austenitic stainless steel as in example 1 was subjected to solution treatment;
comparative example 2 sample: the same starting material 316L austenitic stainless steel as in example 7 was used to treat the stainless steel in a solid solution state;
examples the samples were austenitic stainless steels treated in examples 1 to 8 of the present invention.
Mechanical property test conditions are as follows: the samples were subjected to mechanical property tests according to the yield strength standard test procedure, tensile strength standard test procedure, elongation standard test procedure and vickers hardness standard test procedure, respectively, and the results are shown in table 3.
TABLE 3 mechanical testing data of austenitic stainless steel treated by the present invention
3. Intergranular corrosion performance test (sulfuric acid-copper sulfate method)
Comparative example 1 sample: the same original material 304L austenitic stainless steel as in example 1 was subjected to solution treatment; sample of ratio 2: the same starting material 316L austenitic stainless steel as in example 7 was used to treat the stainless steel in a solid solution state; examples the samples were austenitic stainless steels treated in examples 1 to 8 of the present invention. The results of the above samples were measured according to the intercrystalline corrosion test method of GB/T4334-2008 stainless steel by the sulfuric acid-copper sulfate method, and are shown in Table 4.
TABLE 4 intergranular Corrosion test results of austenitic stainless steels treated according to the invention
| Test specimen | Bending result | The result of the judgment |
| Comparative example 1 | Without intergranular corrosion cracking | Qualified |
| Comparative example 2 | Without intergranular corrosion cracking | Qualified |
| Example 1 | Without intergranular corrosion cracking | Qualified |
| Example 2 | Without intergranular corrosion cracking | Qualified |
| Example 3 | Without intergranular corrosion cracking | Qualified |
| Example 4 | Without intergranular corrosion cracking | Qualified |
| Example 5 | Without intergranular corrosion cracking | Qualified |
| Example 6 | Without intergranular corrosion cracking | Qualified |
| Example 7 | Without intergranular corrosion cracking | Qualified |
| Example 8 | Without intergranular corrosion cracking | Qualified |
As can be seen from tables 3 and 4: compared with stainless steel subjected to solution treatment, the mechanical properties of the stainless steel treated by the method provided by the embodiment of the invention are not statistically different. Therefore, the hot forming method of the stainless steel end socket provided by the invention has the advantages that the hot forming time of the stainless steel end socket is saved by half and the time consumption is short compared with the hot forming time needing solution treatment on the premise of ensuring that the mechanical property and the corrosion resistance of the stainless steel meet the standards, and meanwhile, the hot forming temperature is lower than the curing treatment temperature, the requirement on equipment is low, the energy consumption can be greatly reduced, and the enterprise cost is reduced.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention and not to limit it; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.
Claims (2)
1. A stainless steel end cap thermoforming method comprises the following steps:
placing the stainless steel in a heating furnace at normal temperature for stabilizing treatment, heating the stainless steel to 400 ℃ along with the furnace, then continuously heating the stainless steel to 900-950 ℃ at the heating speed of less than or equal to 150 ℃/h, and carrying out heat preservation treatment to obtain the stabilized stainless steel; when the thickness of the stainless steel is less than 60mm, the heat preservation treatment time is 120-180 min; when the thickness of the stainless steel is more than 60mm, the calculation formula of the heat preservation treatment time is (120+ (material thickness-60) multiplied by 2), and the unit of the heat preservation treatment time is minutes;
carrying out hot pressing treatment on the stainless steel subjected to the stabilizing treatment at 950-750 ℃, and carrying out press forming on the stainless steel, and cooling to obtain a stainless steel end enclosure; after the stainless steel after the stabilization treatment is subjected to press forming treatment, air cooling treatment is adopted when the thickness of the stainless steel after the stabilization treatment is less than 30mm, spray cooling is adopted when the thickness of the stainless steel after the stabilization treatment is 30 mm-60 mm, and water cooling is adopted when the thickness of the stainless steel after the stabilization treatment is more than 60 mm.
2. The method of hot forming a stainless steel header as claimed in claim 1, wherein the stainless steel is 304 austenitic stainless steel or 316 austenitic stainless steel.
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| CN201911011534.3A CN110732605B (en) | 2019-10-23 | 2019-10-23 | Stainless steel seal head hot forming method |
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| CN201911011534.3A CN110732605B (en) | 2019-10-23 | 2019-10-23 | Stainless steel seal head hot forming method |
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| CN110732605B true CN110732605B (en) | 2021-10-15 |
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| CN113492298A (en) * | 2021-07-08 | 2021-10-12 | 南通曙光机电工程有限公司 | Preparation method for press forming of printed circuit board heat exchanger sealing head body |
| CN114317922A (en) * | 2021-12-30 | 2022-04-12 | 南阳汉冶特钢有限公司 | Control method for ensuring stable mechanical property of steam drum plate 13MnNiMoR thermal cycle process |
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|---|---|---|---|---|
| CN104624889A (en) * | 2013-11-12 | 2015-05-20 | 青岛旭升封头有限公司 | Carbon steel head hot pressing technology |
| CN110195152A (en) * | 2019-06-11 | 2019-09-03 | 河南神州精工制造股份有限公司 | A method of improving austenitic stainless steel anti intercrystalline corrosion ability |
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| CN102417958A (en) * | 2011-12-13 | 2012-04-18 | 上海电气电站设备有限公司 | Hot forming process for austenite nitrogen-controlled stainless steel thick-wall head |
| CN102784853B (en) * | 2012-08-22 | 2014-10-22 | 南京德邦金属装备工程股份有限公司 | Manufacturing method of composite board seal head made from high-strength austenite nickel-iron-chromium alloy and austenite stainless steel |
| CN104626725A (en) * | 2013-11-13 | 2015-05-20 | 青岛旭升封头有限公司 | Hot-pressing moulding technology of composite steel plate seal head |
| CN104152658B (en) * | 2014-07-16 | 2016-08-24 | 江苏昆仲机械有限公司 | Cold forming end socket heat treatment method |
| CN106064215A (en) * | 2016-06-03 | 2016-11-02 | 上海新闵（东台）重型锻造有限公司 | Nuclear power pressure vessel integration head pressing forming method |
| CN106734715A (en) * | 2017-01-16 | 2017-05-31 | 兰州兰石重型装备股份有限公司 | 904L+Q345R pressure container of composite board end socket thermoforming process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104624889A (en) * | 2013-11-12 | 2015-05-20 | 青岛旭升封头有限公司 | Carbon steel head hot pressing technology |
| CN110195152A (en) * | 2019-06-11 | 2019-09-03 | 河南神州精工制造股份有限公司 | A method of improving austenitic stainless steel anti intercrystalline corrosion ability |
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