CN114540599A - Gray cast iron surface modification method for improving thermal fatigue performance - Google Patents
Gray cast iron surface modification method for improving thermal fatigue performance Download PDFInfo
- Publication number
- CN114540599A CN114540599A CN202210142825.1A CN202210142825A CN114540599A CN 114540599 A CN114540599 A CN 114540599A CN 202210142825 A CN202210142825 A CN 202210142825A CN 114540599 A CN114540599 A CN 114540599A
- Authority
- CN
- China
- Prior art keywords
- cast iron
- gray cast
- thermal fatigue
- fatigue performance
- gray
- 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.)
- Pending
Links
- 229910001060 Gray iron Inorganic materials 0.000 title claims abstract description 48
- 238000002715 modification method Methods 0.000 title claims abstract description 9
- 238000003756 stirring Methods 0.000 claims abstract description 40
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000003466 welding Methods 0.000 claims abstract description 21
- 230000008569 process Effects 0.000 claims abstract description 10
- 238000012986 modification Methods 0.000 claims description 10
- 230000004048 modification Effects 0.000 claims description 10
- 238000005266 casting Methods 0.000 claims description 8
- 238000005498 polishing Methods 0.000 claims description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 239000010959 steel Substances 0.000 claims description 3
- 229910000677 High-carbon steel Inorganic materials 0.000 claims description 2
- 229910000954 Medium-carbon steel Inorganic materials 0.000 claims description 2
- 229910001315 Tool steel Inorganic materials 0.000 claims description 2
- 239000011261 inert gas Substances 0.000 claims description 2
- 239000002932 luster Substances 0.000 claims description 2
- 241000755266 Kathetostoma giganteum Species 0.000 claims 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 6
- 239000002344 surface layer Substances 0.000 abstract description 6
- 229910002804 graphite Inorganic materials 0.000 abstract description 5
- 239000010439 graphite Substances 0.000 abstract description 5
- 229910001562 pearlite Inorganic materials 0.000 abstract description 4
- 239000011229 interlayer Substances 0.000 abstract description 3
- 230000006872 improvement Effects 0.000 abstract description 2
- 230000000977 initiatory effect Effects 0.000 abstract description 2
- 229910001018 Cast iron Inorganic materials 0.000 description 5
- 239000010410 layer Substances 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 2
- 238000005275 alloying Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000005422 blasting Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000000635 electron micrograph Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000009661 fatigue test Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000004227 thermal cracking Methods 0.000 description 1
Images
Classifications
-
- 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
- C21D5/00—Heat treatments of cast-iron
-
- 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
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention discloses a gray cast iron surface modification method for improving thermal fatigue performance, and aims to solve the technical problems of poor improvement effect, complex process, high cost and unfriendly environment of the conventional gray cast iron thermal fatigue performance. Aiming at the problem of poor thermal fatigue performance of cast gray cast iron in the prior art, the invention adopts friction stir welding to modify the surface of gray cast iron, can effectively improve the microstructure morphology of the surface layer of gray cast iron (coarsening the graphite phase sizes of the surface layer and the sub-surface layer of gray cast iron, and thinning the interlayer spacing of pearlite sheets, thereby improving the threshold value of the initiation and the expansion of thermal fatigue cracks of gray cast iron), thereby improving the thermal fatigue resistance.
Description
Technical Field
The invention relates to the technical field of metal material processing, in particular to a gray cast iron surface modification method for improving thermal fatigue performance.
Background
Gray cast iron refers to cast iron having flake graphite, and is called gray cast iron because a fracture appears dark gray at the time of fracture. The main components are iron, carbon, silicon, manganese, sulfur and phosphorus, the cast iron is the most widely used cast iron, and the yield of the cast iron accounts for more than 80 percent of the total yield of the cast iron.
Gray cast iron has outstanding properties such as good casting performance, shock absorption, heat conductivity and the like, and is widely used as a brake drum material of a heavy truck; the braking effect and the safety reliability of the brake drum play a key role in the safe running of the vehicle. In the braking process of the vehicle, the gray cast iron braking part bears the dual effects of complex stress and alternating temperature, so that thermal cracking and fatigue cracking are easy to occur, and the final brake drum fails. Therefore, improving the thermal fatigue performance of gray cast iron will help the development of the automobile industry and the guarantee of safety performance.
The existing method for improving the thermal fatigue performance of gray cast iron can be mainly summarized into four main categories:
(1) alloying and regulating gray cast iron components (such as Chinese patent documents: CN101191178A, CN102191424A, CN101967601A, CN109468523A, CN110453142A, CN104195423A and the like);
(2) optimizing alloy smelting and preparation processes (such as Chinese patent documents CN103866177A, CN112981224A and the like);
(3) regulating and controlling the microstructure of the cast gray cast iron by heat treatment (such as Chinese patent documents CN104195306A, CN113322369A and the like);
(4) the surface of the cast gray cast iron is modified by methods such as laser, shot blasting and the like (for example, Chinese patent documents CN101792906A, CN108131403A and CN108131403A, Chinese doctor academic paper, Von Xue.
Based on long-term practical research, the inventor finds that the method (1) and the method (2) change the alloy components or the preparation process to increase the manufacturing cost of the gray cast iron, the method (3) is complicated in process, and the method (4) generally improves the surface performance by using single temperature (or force) action, so that the effect of improving the thermal fatigue performance is not obvious sometimes. Therefore, the method which is good in effect, simple, convenient, economical and environment-friendly to improve the thermal fatigue performance of the gray cast iron is lacked at present.
The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is known to a person skilled in the art.
Disclosure of Invention
The invention aims to provide a gray cast iron surface modification method for improving thermal fatigue performance, and aims to solve the technical problems of poor improvement effect, complex process, high cost and environmental friendliness of the conventional gray cast iron thermal fatigue performance.
In order to solve the technical problems, the invention adopts the following technical scheme:
a gray cast iron surface modification method for improving thermal fatigue performance is designed, and comprises the following steps:
(1) polishing the surface of the gray iron casting needing to be modified to remove an oxide layer;
(2) fixing the polished gray iron casting, enabling the surface to be modified to vertically correspond to a stirring head of used friction stir welding equipment, and performing friction stir welding modification treatment on the surface of the gray iron casting;
(3) and polishing to remove an oxide layer on the surface modified by the friction stir welding.
Preferably, in the step (2), the pressing amount of the stirring head in the friction stir welding process is 0.2-1 mm, the advancing speed of the stirring head is 20-100 mm/min, and the rotating frequency of the stirring head is 700-1500 r/min; researches find that the relatively proper stirring and rubbing process conditions can generate a large amount of plastic deformation to refine grains and uniform alloy microstructures, so that the comprehensive performance of the metal material can be greatly improved.
Preferably, in the step (2), the stirring head is made of die steel, tool steel, medium carbon steel or high carbon steel, and the shape of the stirring head is conical or flat; better friction modification results can be produced.
Preferably, in the step (2), the friction stir welding modification treatment is performed under an inert gas atmosphere (such as argon gas).
Preferably, in the step (1) and/or the step (3), the oxide layer is sequentially polished by 400# to 2000# sandpaper, so that the surface of the gray iron casting presents silvery white metallic luster.
Compared with the prior art, the invention has the main beneficial technical effects that:
1. aiming at the problem of poor thermal fatigue performance of cast gray cast iron in the prior art, the invention adopts friction stir welding to modify the surface of gray cast iron, can effectively improve the microstructure morphology of the surface layer of gray cast iron (coarsening the graphite phase sizes of the surface layer and the sub-surface layer of gray cast iron, and thinning the interlayer spacing of pearlite sheets, thereby improving the threshold value of the initiation and the expansion of thermal fatigue cracks of gray cast iron), thereby improving the thermal fatigue resistance.
2. Compared with surface modification methods such as laser, shot blasting and the like, the friction stir welding method has the advantages that the friction stir welding is used for simultaneously applying heat and load to the gray cast iron, the thermal fatigue performance is improved more obviously, and the energy consumption is lower; compared with alloying, smelting process optimization, subsequent heat treatment and other methods, the method provided by the invention is simpler and lower in cost.
Drawings
FIG. 1 is a schematic view of the shape of a stirring head used in the examples of the present invention.
FIG. 2 is an electron micrograph of HT250 microstructure in an example of the present invention, wherein (a) - (b) are the original samples; (c) and (d) is a friction stir welding surface modification sample.
FIG. 3 is a schematic diagram of thermal fatigue temperature and cycle steps in an embodiment of the invention.
FIG. 4 shows the morphology of HT250 thermal fatigue cracks according to an embodiment of the present invention: wherein (a) - (b) are raw samples; (c) and (d) is a friction stir welding surface modification sample.
Detailed Description
The following examples are intended to illustrate the present invention in detail and should not be construed as limiting the scope of the present invention in any way.
The instruments and devices referred to in the following examples are conventional instruments and devices unless otherwise specified; the raw materials are all conventional raw materials which are sold in the market and are not particularly specified; the related detection and test methods are conventional methods unless otherwise specified.
The gray cast iron generally includes HT150, HT200, HT250, etc. designations, and the structure is similar flake graphite and pearlite, with the differences in structure characteristic dimensions and material strength, and thus is exemplified in the following examples by HT250, which is commonly used in brake drum materials.
Example (b): taking HT250 gray cast iron as an example, the surface of the gray cast iron is modified by friction stir welding, so that the thermal fatigue property of the gray cast iron is improved, and the method comprises the following specific steps:
1. and sequentially polishing the surface to be modified of the HT250 sample by using 400# to 2000# sandpaper to remove an oxide layer.
2. Fixing the polished HT250 sample piece, enabling the surface to be modified to be perpendicular to a stirring head of friction stir welding equipment (model FFSW-AM16-2D, Cyfossite), modifying the surface of gray cast iron by using friction stir welding under the argon protection atmosphere, wherein the stirring head is made of H13 hot-working die steel and is cone-head-shaped (refer to figure 1), and the process parameters are as follows:
the pressing amount of the stirring head is 0.4 mm, the advancing speed of the stirring head is 40 mm/min, and the rotating frequency of the stirring head is 1000 r/min.
3. And sequentially polishing the surface of the sample subjected to surface modification treatment by using 400# to 2000# sandpaper to remove an oxide layer.
4. The surface graphite size of the sample after friction stir welding surface modification became large (aspect ratio increased) and the pearlite sheet interlayer spacing decreased, as shown in fig. 2.
5. Performing thermal fatigue experiments on the original sample and the modified sample (the cycle process flow is shown in figure 3), setting the high temperature to 700 ℃, performing thermal cycle for 30 times, then increasing the temperature to 800 ℃, and performing thermal cycle for 26 times; the test results are shown in fig. 4, and it can be seen that after the thermal fatigue test, the length and the number of the cracks of the HT250 sample after the surface modification are both smaller than those of the original HT250 sample, which indicates that the thermal fatigue performance of HT250 is effectively improved by the friction stir welding process.
While the invention has been described in detail with reference to the drawings and examples, it will be understood by those skilled in the art that various changes in the form and details may be made therein without departing from the spirit and scope of the invention.
Claims (5)
1. A gray cast iron surface modification method for improving thermal fatigue performance is characterized by comprising the following steps:
(1) polishing the surface of the gray iron casting needing to be modified to remove an oxide layer;
(2) fixing the polished gray iron casting, enabling the surface to be modified to vertically correspond to a stirring head of used friction stir welding equipment, and performing friction stir welding modification treatment on the surface of the gray iron casting;
(3) and polishing to remove the oxide layer on the friction stir welding modified surface.
2. The method for modifying a surface of gray cast iron with improved thermal fatigue performance as claimed in claim 1, wherein in said step (2), the pressing amount of the stirring head during friction stir welding is 0.2 to 1mm, the advancing speed of the stirring head is 20 to 100 mm/min, and the rotating speed of the stirring head is 700 to 1500 r/min.
3. The method for modifying a surface of gray cast iron with improved thermal fatigue performance as claimed in claim 1, wherein in said step (2), said stirring head is made of die steel, tool steel, medium carbon steel or high carbon steel, and the shape of the stirring head is cone-head type or flat-head type.
4. A method of modifying a surface of gray cast iron for improving thermal fatigue performance as claimed in claim 1, wherein in said step (2), the friction stir welding modification process is performed under an inert gas atmosphere.
5. A gray cast iron surface modification method for improving thermal fatigue performance as claimed in claim 1, characterized in that in step (1) and/or step (3), oxide layers are sanded with 400# to 2000# sandpaper in sequence, based on the gray cast iron member surface showing silvery white metallic luster.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210142825.1A CN114540599A (en) | 2022-02-16 | 2022-02-16 | Gray cast iron surface modification method for improving thermal fatigue performance |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210142825.1A CN114540599A (en) | 2022-02-16 | 2022-02-16 | Gray cast iron surface modification method for improving thermal fatigue performance |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114540599A true CN114540599A (en) | 2022-05-27 |
Family
ID=81675653
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210142825.1A Pending CN114540599A (en) | 2022-02-16 | 2022-02-16 | Gray cast iron surface modification method for improving thermal fatigue performance |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114540599A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090065553A1 (en) * | 2007-09-07 | 2009-03-12 | Burg James T | Friction stir welding apparatus |
| US20100136369A1 (en) * | 2008-11-18 | 2010-06-03 | Raghavan Ayer | High strength and toughness steel structures by friction stir welding |
| JP2012066287A (en) * | 2010-09-24 | 2012-04-05 | Osaka Univ | Tool used for friction stir process, and friction stir process |
| CN105728934A (en) * | 2016-04-25 | 2016-07-06 | 西安建筑科技大学 | Electromagnetic auxiliary friction stir welding device and method for refining crystal grains by aid of same |
| CN108296625A (en) * | 2018-02-09 | 2018-07-20 | 西京学院 | A kind of xenogenesis thickness spheroidal graphite cast-iron connection method based on agitating friction weldering |
| CN111850381A (en) * | 2020-07-14 | 2020-10-30 | 驻马店中集华骏铸造有限公司 | Method for producing gray cast iron |
-
2022
- 2022-02-16 CN CN202210142825.1A patent/CN114540599A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090065553A1 (en) * | 2007-09-07 | 2009-03-12 | Burg James T | Friction stir welding apparatus |
| US20100136369A1 (en) * | 2008-11-18 | 2010-06-03 | Raghavan Ayer | High strength and toughness steel structures by friction stir welding |
| JP2012066287A (en) * | 2010-09-24 | 2012-04-05 | Osaka Univ | Tool used for friction stir process, and friction stir process |
| CN105728934A (en) * | 2016-04-25 | 2016-07-06 | 西安建筑科技大学 | Electromagnetic auxiliary friction stir welding device and method for refining crystal grains by aid of same |
| CN108296625A (en) * | 2018-02-09 | 2018-07-20 | 西京学院 | A kind of xenogenesis thickness spheroidal graphite cast-iron connection method based on agitating friction weldering |
| CN111850381A (en) * | 2020-07-14 | 2020-10-30 | 驻马店中集华骏铸造有限公司 | Method for producing gray cast iron |
Non-Patent Citations (3)
| Title |
|---|
| KOICHI IMAGAWA, ETAL.: "Effects of Tool Geometry on Hardened Layer of Friction Stir Processed Cast Iron", MATERIALS TRANSACTIONS, vol. 53, no. 11, pages 1952 - 1955 * |
| 彭善富: "光电照明产品 密封与防水技术", 华南理工大学出版社, pages: 96 * |
| 雷霆: "钛及钛合金", 30 April 2018 (2018-04-30), pages 538 - 540 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US9464335B2 (en) | Method for improving fatigue strength of cast iron material | |
| CN108517461B (en) | High-performance martensitic stainless steel flange and manufacturing method thereof | |
| Yang et al. | The effect of inclusions on the fatigue behavior of fine-grained high strength 42CrMoVNb steel | |
| CN103215428A (en) | Thermal treatment method of spline shaft head of transmission shaft | |
| CN106826571A (en) | A kind of method of gear surface complex intensifying | |
| CN114540599A (en) | Gray cast iron surface modification method for improving thermal fatigue performance | |
| CN100999781A (en) | High manganese steel frog surface explosive harden tech. | |
| US9340846B2 (en) | Method for improving fatigue strength of cast iron material | |
| CN112708733A (en) | Processing technology of petroleum drill rod joint | |
| CN106244979A (en) | A kind of method of carbon Chromador Nitric white hardness in raising | |
| US9102992B2 (en) | Method for improving fatigue strength of cast iron material | |
| Tokaji et al. | Fatigue behaviour of beta Ti-22V-4Al alloy subjected to surface-microstructural modification | |
| CN115341153A (en) | Bar for new energy automobile motor shaft and preparation method thereof | |
| CN105385952B (en) | A kind of High Speed Railway Trains wheel steel and its Technology for Heating Processing | |
| JPH08127851A (en) | Production of forged aluminum alloy wheel excellent in corrosion fatigue resistance | |
| Ji et al. | Effect of shot peening on fatigue performance of ductile iron castings | |
| JPH073324A (en) | Production of steel having excellent fatigue strength | |
| JPH10217122A (en) | Treatment method for metal mold surface | |
| CN111500940A (en) | Alloy steel forged brake disc with friction spark inhibiting characteristic and manufacturing method thereof | |
| CN114134291B (en) | Method for prolonging fatigue life of high-strength variable-cross-section transverse plate spring | |
| JPS60168910A (en) | Shotpeened drive shaft | |
| Haiko et al. | Effect of Rapid Induction Tempering on the Mechanical Properties and Microstructure of Ultra-High Strength Steel | |
| US3471340A (en) | Regeneration of refused rolls | |
| CN114164318B (en) | Preparation method of slurry pump cylinder sleeve | |
| JP4253953B2 (en) | Method for producing continuous cast extra heavy steel plate with excellent HIC resistance |
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 |