WO1997003214A1 - Nitriding steel excellent in formability and nitriding characteristics and products of press forming - Google Patents
Nitriding steel excellent in formability and nitriding characteristics and products of press forming Download PDFInfo
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- WO1997003214A1 WO1997003214A1 PCT/JP1996/001932 JP9601932W WO9703214A1 WO 1997003214 A1 WO1997003214 A1 WO 1997003214A1 JP 9601932 W JP9601932 W JP 9601932W WO 9703214 A1 WO9703214 A1 WO 9703214A1
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- nitriding
- steel
- steel sheet
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- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 114
- 239000010959 steel Substances 0.000 title claims abstract description 114
- 238000005121 nitriding Methods 0.000 title claims abstract description 72
- 150000004767 nitrides Chemical class 0.000 claims abstract description 33
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000012535 impurity Substances 0.000 claims abstract description 7
- 229910052742 iron Inorganic materials 0.000 claims abstract description 7
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 4
- 239000010960 cold rolled steel Substances 0.000 claims description 21
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 15
- 229910052799 carbon Inorganic materials 0.000 abstract description 9
- 229910052719 titanium Inorganic materials 0.000 abstract description 9
- 229910052720 vanadium Inorganic materials 0.000 abstract description 6
- 229910052748 manganese Inorganic materials 0.000 abstract description 4
- 229910052804 chromium Inorganic materials 0.000 abstract description 3
- 239000004615 ingredient Substances 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 40
- 239000007789 gas Substances 0.000 description 29
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 18
- 238000004519 manufacturing process Methods 0.000 description 15
- 238000012360 testing method Methods 0.000 description 15
- 238000000034 method Methods 0.000 description 13
- 239000000203 mixture Substances 0.000 description 11
- 238000000137 annealing Methods 0.000 description 10
- 238000005096 rolling process Methods 0.000 description 10
- 239000002344 surface layer Substances 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- 238000007796 conventional method Methods 0.000 description 7
- 238000010438 heat treatment Methods 0.000 description 7
- 239000003921 oil Substances 0.000 description 7
- 238000001953 recrystallisation Methods 0.000 description 7
- 230000009467 reduction Effects 0.000 description 7
- 238000009792 diffusion process Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 6
- 238000000227 grinding Methods 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 238000009749 continuous casting Methods 0.000 description 5
- 238000005452 bending Methods 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005098 hot rolling Methods 0.000 description 4
- 238000012545 processing Methods 0.000 description 4
- 235000013339 cereals Nutrition 0.000 description 3
- 238000005097 cold rolling Methods 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 229910001209 Low-carbon steel Inorganic materials 0.000 description 2
- 238000005299 abrasion Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910017464 nitrogen compound Inorganic materials 0.000 description 2
- 150000002830 nitrogen compounds Chemical class 0.000 description 2
- 235000012149 noodles Nutrition 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000004904 shortening Methods 0.000 description 2
- 230000003313 weakening effect Effects 0.000 description 2
- 229910000915 Free machining steel Inorganic materials 0.000 description 1
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000005238 degreasing Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000010409 ironing Methods 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 230000001376 precipitating effect Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004080 punching Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
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
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- 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
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
Definitions
- the present invention provides nitriding steel with excellent formability and nitriding properties, and parts that require wear resistance, fatigue resistance, and seizure resistance, such as tools, machine structural parts, and automobile parts made of this steel.
- the present invention relates to a press-formed body excellent in workability, particularly deep drawability and wear resistance, which is used in a steel sheet. Background technology
- nitriding in which nitrogen is infiltrated into steel, has been used to produce parts with high surface and internal hardness (excluding thin steel sheet molded parts).
- the steel used for these parts (for example, JP-A-59-31850 and JP-A-59-50158) contains a large amount of nitriding-promoting elements, so it has high strength and is difficult to work. It is shaped by grinding, and then nitrided to increase its hardness. Therefore, it took time and money to form the shape.
- a simple and low-cost forming method there is a forming method by press working, and if a steel plate such as a low-carbon steel plate or an ultra-low-carbon steel plate (for example, Japanese Patent Publication No. 44-18066) is applied, a press-formed body can be manufactured. can be done.
- a steel plate such as a low-carbon steel plate or an ultra-low-carbon steel plate (for example, Japanese Patent Publication No. 44-18066)
- a press-formed body can be manufactured. can be done.
- the shape of the part could be molded, it was not possible to obtain high surface hardness, which is important for wear resistance, fatigue strength, and seizure resistance.
- the conventionally known methods cannot produce a press-formed body that is easy to form and has a desired high surface hardness. rice field.
- a further object of the present invention is to provide a press-formed body having a surface hardness of Hv 400 or more and a critical drawing ratio of 1.9 or more.
- the present invention when a steel sheet is subjected to press working such as deep drawing, an appropriate amount of dislocations are added to the steel sheet, and the dislocations promote the diffusion of nitrogen and the formation of nitrides, thereby forming a nitride hardened layer in the steel sheet. It was invented based on the technical knowledge that it can be formed on the surface in a short time and at a desired depth.
- the content of C is adjusted to 0.01 according to the degree of difficulty of molding based on the shape of the part or the degree of required strength of the part.
- the high C content steel has a critical drawing ratio (the ratio of the diameter of the disk-shaped material (blank) to the inner diameter of the cup bottom at which breakage occurs during drawing (LDR)) of 1.9 or more.
- a hardness Hv of 400 or more at a position 30 m from the surface and a low C content steel can simultaneously have a critical drawing ratio LDR of 0.2 or more and a hardness ⁇ of 400 or more.
- the present invention is a case of high C content steel, C: 0.01 to less than 0.08%, Si: 0.005 to 1.00%, Mn: 0.010 to 3.00%, P: 0.001 to 0.150%, N: 0.0002% by weight.
- Cr more than 0.15 to 5.00%
- A1 more than 0.060 to 2.00%
- Ti 0.010% or more and less than 4C [%]
- V 0 010 to 1 00%
- It is a nitriding steel with excellent formability and nitriding properties, containing one or two of the following, the balance being iron and unavoidable impurities. Both are press-formed bodies with a hard nitride layer formed on one side.
- the steel sheet of the present invention is used for parts that require strength, such as mechanical structural parts, and/or parts that are easy to form.
- the present invention as a case of low C content steel, contains C: 0.0002 to less than 0.0100%, Si: 0.005 to 1.00%, Mn: 0.010 to 3.00%, P: 0.001 to 0.150%, N: 0.0002% by weight. Cr: more than 0.80 to 5.00%, and as nitride hardening element group, V: more than 0.10 to 1.00%, A1: more than 0.10 to 2.00%, Ti: 0.010 to 1.00%. It contains one or more kinds, and if necessary, further contains Nb: 0.005 to 0.060% or B: 0.0005 to 0.0050%, the balance being iron and unavoidable impurities.
- the steel sheet of the present invention is used for parts that do not require particular strength and/or have shapes that are difficult to form. Brief description of the drawing
- FIG. 2 is a diagram showing the relationship between the V concentration and the depth at which surface hardness Hv 400 is obtained. Best Mode for Carrying Out the Invention
- each element is contained within the following range.
- C is an element that affects the formability of steel, and as the content increases, the formability deteriorates. Also, if the content is large, it accelerates the deterioration of formability when other elements are added. Therefore, less than 0.08%. Also, if it is less than 0.01%, the strength for mechanical structure is insufficient, so 0.01% is the lower limit.
- Si is added to improve moldability, but if it is less than 0.005%, the manufacturing cost rises dramatically and becomes uneconomical. 1.00% is set as the upper limit.
- Mn is added to improve moldability, but if it is less than 0.010%, the manufacturing cost rises dramatically and becomes uneconomical. 3.00% is the upper limit.
- P is an element that can increase the strength without impairing the formability, and is added according to the strength level. The lower limit is set at 0.001%, and if it exceeds 0.150, the problem of secondary work embrittlement occurs, so the upper limit is set at 0.150%.
- N should be as small as possible in order to ensure moldability, but if it is less than 0.0002%, the manufacturing cost will rise dramatically and it will not be economical.
- the upper limit is set at 0.0100% because it deteriorates.
- Cr, Al, Ti, and V are group of nitriding promoting elements for enhancing nitriding. If the amount of addition is small, the nitridability cannot be enhanced, so the lower limit is specified, and if the amount of addition is large, the formability becomes unusable for practical use, so the upper limit is specified according to the composition of the steel.
- nitriding hardening is a very important element for nitriding hardening, and if it is 0.15% or less, the amount of increase in hardness due to nitriding is small, so it must be contained in excess of 0.15%. Up to 5.00% o
- A1 is usually added as a deoxidizing component, and it is necessary to add 0.005% or more to prevent defects such as blowholes from occurring.
- A1 has a strong affinity with nitrogen and is an element that makes the surface layer of the nitride layer very hard. Therefore, it contains more than 0.060%. Preferably, it is 0.080% or more. Also, if it exceeds 2.00%, the formability deteriorates, so 2.00% is made the upper limit.
- Ti is a more powerful nitride-forming element than Cr and A1, and is an element that strongly promotes nitriding even if the nitriding treatment time is short, so that a surface hardened layer can be obtained in a short treatment time. If it is less than 0.010%, the amount of increase in hardness due to nitriding is small, so 0.010% is the lower limit.
- Ti is a strong carbide-forming element, and when the C content (C [%]) is four times or more, all the carbon in the steel becomes coarse precipitates, weakening the adhesion between grains, Slab cracking is very likely to occur during hot rolling. Therefore, the upper limit is less than 4 C C %). That is, since TiC is formed as a carbide, C > (12/48) Ti.
- a steel having the composition shown in Table 1 was melted and made into a slab by continuous casting according to a conventional method. Then, it is heated to 1200°C in a heating furnace, hot-rolled at a finishing temperature of 910°C or higher, coiled at 600°C, pickled, and cold-rolled at a rolling reduction of 80%. After rolling, the steel was recrystallized and annealed at 800°C for 60 seconds to form a cold-rolled steel sheet.
- a press-formed body with a critical drawing ratio of 1.9 was produced, and this was used as a test piece to test the ease of forming a surface hardened layer (promptness of nitriding) depending on the nitriding treatment time.
- v accelerates the diffusion of nitrogen and makes it penetrate into the interior of the steel, so a thick nitride layer can be obtained on the surface of the steel. If it is less than 0.010%, the amount of hardness increase due to nitriding is small, so 0.010% is the lower limit, and 1.00
- V is a carbide-forming element that forms carbon in steel as precipitates, weakening the adhesion between crystal grains and making slab cracks more likely, though not as much as Ti. Therefore, it is preferably 5.67 times (5.67C ⁇ %)) or less than the C content, that is, C > (12/51) (3/4) V or less because V 4 C 3 is formed as a carbide.
- the depth range from the surface where hardness (Hv) 400 of the hardened surface layer can be obtained was determined by the following experiment for the nitrogen penetration effect due to the addition of V.
- a press-formed body similar to that shown in Table 1 was formed from this cold-rolled steel sheet, and the hardening depth of the surface-hardened layer due to nitriding treatment was tested. After making the test piece
- the steel sheet In order to secure the formability of the steel sheet, especially the deep drawability, it contains the following components.
- C is an element that affects the deep drawability of steel, and when the content increases, the deep drawability deteriorates. Also, if the content is large, deterioration of deep drawability is accelerated when other elements are added. Therefore, less than 0.0100%. In addition, if it is less than 0.0002%, the production cost will rise dramatically due to an increase in the high-purification treatment load of the steel, which is not economical, so 0.0002% is made the lower limit.
- the lower limit is set at 0.010%.
- P is an element that can increase the strength without impairing the deep drawability, and is added according to the strength level. is the lower limit, and if it exceeds 0.150%, the problem of secondary work embrittlement occurs, so 0.150% is the upper limit.
- N should be as small as possible.
- the upper limit is set at 0.0100% because the properties deteriorate.
- the present invention can contain Nb in the range of 0.005% to 0.060%. Nb is added in order to form fine carbides, nitrides and carbonitrides in the steel and to prevent the deterioration of deep drawability due to the presence of solid solution C and N.
- B may be contained in an amount of 0.0005% or more and 0.0050% or less as an element for preventing secondary work embrittlement.
- B is added for the purpose of strengthening the grain boundary strength of steel, which is weakened due to low carbon content, and preventing secondary work embrittlement. If B is less than 0.0005%, the effect of preventing secondary work embrittlement is small, so the lower limit is set at 0.0005%. Since B has a strong affinity with nitrides, even in steels containing nitride-forming elements within the compositional range of the steel materials used in the present invention, B does not interfere with the nitriding processability of the steels. Further improvements are possible.
- the sample Not in Table 3 corresponds to the sample N ⁇ in Tables 8(1) to 8(6).
- Cr, Al, V, and Ti are elements that promote nitridation to enhance nitridability.
- A1 is usually added as a deoxidizing component, and it is necessary to add 0.005% or more to prevent defects such as blowholes from occurring.
- the lower limit is 0.005%.
- A1 has a strong affinity with nitrogen and is an element that makes the surface layer of the nitride layer very hard. However, if it exceeds 2.00%, the deep drawability deteriorates, so it is added with 2.00% as the upper limit.
- V accelerates the diffusion of nitrogen and penetrates into the interior of the steel, making it possible to obtain a thick nitride layer on the surface of the steel. If it is 0.10% or less, the amount of increase in hardness due to nitriding is small, so the lower limit is set to more than 0.10%, and if it exceeds 1.00%, the deep drawability deteriorates, so the upper limit is set to 1.00%.
- Nitride is an element that strongly promotes nitridation even if the nitriding treatment time is short because it easily causes the nucleation of nitrides, and a hardened surface layer can be obtained in a short treatment time. If it is less than 0.010%, the amount of increase in hardness due to nitriding is small, so 0.010% is the lower limit, and if it exceeds 1.00%, the deep drawability deteriorates, so 1.00% is the upper limit. When Ti is also added to improve deep drawability, it is preferably 0.005% or more.
- Ti is a strong nitriding element capable of shortening the nitriding time.
- the steel of the composition shown in Table 4 is melted, and the same manufacturing method as in Table 1 A cold-rolled steel sheet was obtained.
- a press-formed body with a critical drawing ratio of 1.9 was made from this cold-rolled steel sheet, and this was used as a test piece to test the easiness of formation of a surface hardened layer (promptness of nitriding) depending on the nitriding treatment time.
- After preparing the test piece it was nitrided at 570°C in a mixed atmosphere gas of NH 3 gas and an endothermic gas while changing the time, and cooled with oil.
- the hardness (Hv) of the surface hardened layer was measured using a micro Vickers hardness tester.
- the composition is adjusted as described above, but when deep drawability is strictly required, the content of C is set to 0.0002% or more and less than 0.0100%, and the amount of Ti is increased to precipitate and fix C and N.
- any conditions such as heating after casting and rolling may be used.
- hot rolling there are no particular restrictions on hot rolling or before hot rolling, but coiling at 500°C or higher is preferable for improving workability.
- cold rolling it is desirable to apply cold rolling at a rolling reduction of 50% or more after that. A cold rolling of 50% or more results in high formability, but 70% or more is most desirable.
- recrystallization annealing is performed, and the method can be either box annealing or continuous annealing.
- Annealing conditions are not particularly specified, but it is preferable to carry out the annealing at a temperature higher than the recrystallization temperature and at a temperature not higher than 900°C at which no coarse grains are formed. Further, after that, the steel sheet of the present invention may be subjected to temper rolling, oil coating, solid lubricating oil, etc., in order to improve the workability and the appearance after working.
- the hot-rolled steel sheet or cold-rolled steel sheet formed as described above is subjected to press working such as deep drawing. At this time, an appropriate amount of dislocations is added to the steel sheet. Dislocations added by working such as deep drawing promote the diffusion of nitrogen and the formation of nitrides, making it possible to obtain a nitride hardened layer in a short time, so that a compact having excellent wear resistance can be obtained. can . In addition, this hard layer makes it difficult for surface cracks to occur and improves fatigue strength and seizure resistance.
- the formability of the present invention can be applied not only to deep drawing but also to bending, ironing, punching, etc., which can give an appropriate amount of dislocations.
- a hard nitride layer can be formed on the surface of the steel sheet of the compact by subjecting the compact to a nitriding treatment after forming the compact into a predetermined shape.
- the hard nitride layer of the present invention refers to a surface nitrogen compound layer or a hard nitrogen diffusion layer formed between the nitrogen compound layer and the steel sheet.
- Nitriding includes gas nitriding, gas nitrocarburizing, salt bath nitrocarburizing, ion nitriding, oxynitriding, and sulphonitriding. It does not matter which processing method is used. Also, the treatment time can be varied appropriately to obtain the desired nitride layer depth.
- the thickness of the obtained surface nitride layer may be reduced by means such as grinding to adjust the layer thickness or to adjust the surface roughness.
- the hardness of the hard nitride layer should be about 400 or more in micro Vickers. Although the upper limit of hardness is not limited, it is approximately 1,500 with the current nitriding technology.
- the thickness of the nitride-concentrated hard layer is effective when it is 10/m or more, but a thickness of 200 m or more is desirable in order to stably exhibit the effect.
- a steel having the composition of the present invention is melted, and a slab is cast by continuous casting according to a conventional method.
- This slab is heated in a heating furnace in the range of 1000 to 1300°C, hot rolled at a finishing temperature of 700 to 1000°C, and rolled in the temperature range of room temperature to 850°C. to manufacture coiled hot-rolled steel sheets.
- the hot-rolled steel sheet After pickling the hot-rolled steel sheet, it is cold-rolled at a reduction rate of 30% or more, and then recrystallization annealing is performed at a temperature range of 600 to 900 ° C for 1 to 300 seconds. to produce cold-rolled steel sheets.
- the obtained hot-rolled sheet or cold-rolled sheet is subjected to deep drawing (e.g., a limiting drawing ratio of 1.9 or more), degreased, and then extruded in a mixed atmosphere gas of NH3 gas and endothermic gas at a temperature range of 450 to 650. 0. Nitriding for 1-100 hours and cooling to produce parts with a surface hardness of Hv 400 or higher.
- a steel with the components shown in Table 5 was melted and made into a slab by continuous casting according to a conventional method. Then, it is heated to 1200 ° C in a heating furnace, hot rolled at a finishing temperature of 910 ° C or higher, coiled at 700 ° C, then pickled, and subjected to a rolling reduction of 80%. After cold rolling, recrystallization annealing was performed at 800°C for 60 seconds to obtain a cold-rolled steel sheet with a thickness of 1.2 mm. The resulting cold-rolled steel sheet was cut into discs (blanks) of 60 ⁇ , and press-formed into cup-shaped deep-drawn bodies at a drawing ratio of 2.0.
- a steel having the composition shown in Table 6 was melted and continuously cast into a slab according to a conventional method. Then, it is heated to 1250°C in a heating furnace, hot rolled at a finishing temperature of 910°C or higher, coiled at 530°C, pickled, and cold rolled at a rolling reduction of 75%. After rolling, the steel sheet was subjected to recrystallization annealing at 780°C for 40 seconds to obtain a cold-rolled steel sheet having a thickness of 1.8 mm. The resulting cold-rolled steel sheet was cut into 80 ⁇ discs (blanks), and press-formed into cup-shaped deep-drawn bodies at a drawing ratio of 2.0.
- This part was nitrided at 570°C for 4 hours in a mixed atmosphere gas of NH 3 gas and endothermic gas, and cooled with oil. A 10 ⁇ 10 mm test piece was then cut from the bottom portion. As a result, a test piece having hard nitride layers on both sides was prepared. In addition, during the nitriding process, the mouth of some cup-shaped parts is sealed, and only the outer surface of the cup-shaped part is exposed to the mixed atmosphere gas of NH 3 gas and endothermic gas without exposing the inner surface. A hard nitride layer was formed. As a result, a test piece having a hard nitride layer on only one side was prepared.
- Rotational abrasion was applied to these specimens by pressing a rotary abrasive plate with a constant load. Abrasion resistance was evaluated by the total number of revolutions of the abrasive plate until the thickness of the test piece decreased by 0.1 mm at maximum.
- the deep-drawn press-formed body according to the present invention has high surface hardness and excellent wear resistance.
- a steel having the composition shown in Table 7 (1) was melted and made into a slab by continuous casting according to a conventional method. Then, it is heated to 1200 ° C in a heating furnace, hot rolled at a finishing temperature of 910 ° C or higher, coiled at the coiling temperature shown in Table 7 (2), then pickled and heated.
- Rolled steel plate A steel having the composition shown in Table 7 (1) was melted and made into a slab by continuous casting according to a conventional method. Then, it is heated to 1200 ° C in a heating furnace, hot rolled at a finishing temperature of 910 ° C or higher, coiled at the coiling temperature shown in Table 7 (2), then pickled and heated.
- Rolled steel plate was melted and made into a slab by continuous casting according to a conventional method. Then, it is heated to 1200 ° C in a heating furnace, hot rolled at a finishing temperature of 910 ° C or higher, coiled at the coiling temperature shown in Table 7 (2), then pickled and heated.
- the hot-rolled steel sheets were cold-rolled at the rolling reduction shown in Table 7 (2), and then subjected to recrystallization annealing at 800°C for 60 seconds to obtain cold-rolled steel sheets.
- Disks (blanks) with a diameter of 60 squares were cut out of the obtained hot-rolled and cold-rolled steel sheets, and cup parts were press-formed at drawing ratios of 1.9 and 2.0. Cup parts were molded and the limiting drawing ratio (LDR) of each sample was obtained.
- Nitridability was evaluated by measuring the hardness (Hv) at 30 m from the surface using a micro Vickers hardness tester.
- Example 2 Steels having the compositions shown in Tables 8 (1) to 8 (3) were melted and made into slabs by continuous casting according to a conventional method. Then, it is heated to 1200 ° C in a heating furnace, hot rolled at a finishing temperature of 910 ° C or higher, coiled at the coiling temperature shown in Table 8 (4) to Table 8 (6), and then , and pickled to form a hot-rolled steel sheet.
- the hot-rolled steel sheets were cold-rolled at the rolling reductions shown in Tables 8 (4) to 8 (6), and then subjected to recrystallization annealing at 800°C for 60 seconds to obtain cold-rolled steel sheets.
- Disks (blanks) with a diameter of 60 mm were cut out of the obtained hot-rolled steel sheets and cold-rolled steel sheets, and press-formed into cup parts at drawing ratios of 2.0 and 2.1. Cup parts were formed and the limiting drawing ratio (LDR) of each sample was obtained.
- LDR limiting drawing ratio
- a test piece was prepared and degreased, then nitrided in a mixed atmosphere gas of NH 3 gas and endothermic gas at 570° C. for 4 hours, and cooled with oil. Nitridability was evaluated by measuring the hardness (Hv) at a position of 30/m from the surface using a micro Vickers hardness tester.
- a steel sheet having high nitridability and excellent deep drawability can be provided, so that a desired depth of nitriding can be obtained in a short nitriding treatment time. Also, by using the press-formed body of the present invention, it is possible to manufacture tools, machine structural parts, automobile parts, etc., which also have wear resistance, fatigue resistance strength, and seizure resistance. Therefore, the industrial applicability of the present invention is extremely large.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Sheet Steel (AREA)
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/809,012 US5810948A (en) | 1995-07-12 | 1996-07-11 | Nitriding steel excellent in formability and susceptibility to nitriding and press formed article thereof |
KR1019970701601A KR100222239B1 (ko) | 1995-07-12 | 1996-07-11 | 성형성과 질화성이 우수한 질화용 강판 및 그의 프레스 성형체 |
EP96923063A EP0778357A4 (en) | 1995-07-12 | 1996-07-11 | NITRURING STEEL HAVING EXCELLENT FORMATABILITY, NITRURATION CHARACTERISTICS AND PRODUCTS OBTAINED BY PRESS FORMING |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP7/176083 | 1995-07-12 | ||
JP7/176082 | 1995-07-12 | ||
JP17608395A JP3153108B2 (ja) | 1995-07-12 | 1995-07-12 | 深絞り性に優れた窒化用鋼板およびそのプレス成形体 |
JP17608295A JPH0925543A (ja) | 1995-07-12 | 1995-07-12 | 成形性に優れた窒化用鋼板およびそのプレス成形体 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997003214A1 true WO1997003214A1 (en) | 1997-01-30 |
Family
ID=26497141
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP1996/001932 WO1997003214A1 (en) | 1995-07-12 | 1996-07-11 | Nitriding steel excellent in formability and nitriding characteristics and products of press forming |
Country Status (6)
Country | Link |
---|---|
US (1) | US5810948A (ja) |
EP (1) | EP0778357A4 (ja) |
KR (1) | KR100222239B1 (ja) |
CN (1) | CN1166185A (ja) |
CA (1) | CA2199032A1 (ja) |
WO (1) | WO1997003214A1 (ja) |
Families Citing this family (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
ES2103242T3 (es) * | 1995-06-30 | 1999-01-16 | Picard Fa Carl Aug | Plancha matriz para una sierra, tal como una sierra circular o una sierra alternativa, una muela cortadora, una herramienta de corte o de rasqueteado. |
US20100055496A1 (en) * | 2006-02-23 | 2010-03-04 | Iljin Light Metal Co., Ltd. | Steel having high strength |
JP5521970B2 (ja) * | 2010-10-20 | 2014-06-18 | 新日鐵住金株式会社 | 冷鍛窒化用鋼、冷鍛窒化用鋼材および冷鍛窒化部品 |
CN103958713B (zh) * | 2011-11-21 | 2016-02-17 | 新日铁住金株式会社 | 氮化用热轧钢板、氮化用冷轧钢板及它们的制造方法、以及使用它们的汽车部件 |
WO2014019964A1 (en) * | 2012-07-30 | 2014-02-06 | Tata Steel Nederland Technology Bv | A method for producing a high strength strip steel with a good deep drawability and a high strength steel produced thereby |
ES2748699T3 (es) | 2014-06-13 | 2020-03-17 | Nippon Steel Corp | Lámina de acero para tratamiento de nitruración suave, método para fabricarla y acero con nitruración suave |
CN106011649B (zh) * | 2016-07-25 | 2018-04-20 | 马钢(集团)控股有限公司 | 一种具有优良渗氮性能和冲压性能的低碳冷轧钢板及其制备方法 |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS53113214A (en) * | 1977-03-15 | 1978-10-03 | Nisshin Steel Co Ltd | Steel for nitriding use having high core hardness after nitriding treatment |
JPS5576046A (en) * | 1978-11-30 | 1980-06-07 | Nisshin Steel Co Ltd | Ultra low carbon nitriding steel |
JPH0280539A (ja) * | 1988-09-16 | 1990-03-20 | Nisshin Steel Co Ltd | 窒化用鋼素材 |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS52128821A (en) * | 1976-04-12 | 1977-10-28 | Nippon Steel Corp | Preparation of high tensile steel having superior low temperature toughness and yield point above 40 kg/pp2 |
JP2818675B2 (ja) * | 1989-12-28 | 1998-10-30 | 川崎製鉄株式会社 | 表面調整冷延鋼板の製造方法 |
JPH0559488A (ja) * | 1991-09-02 | 1993-03-09 | Kobe Steel Ltd | 機械加工性の優れた析出硬化型高強度軟窒化用鋼 |
JP3296599B2 (ja) * | 1992-09-21 | 2002-07-02 | 川崎製鉄株式会社 | 高い張り剛性を有すると共にプレス成形性にも優れるプレス加工用薄鋼板 |
-
1996
- 1996-07-11 EP EP96923063A patent/EP0778357A4/en not_active Withdrawn
- 1996-07-11 US US08/809,012 patent/US5810948A/en not_active Expired - Fee Related
- 1996-07-11 WO PCT/JP1996/001932 patent/WO1997003214A1/ja not_active Application Discontinuation
- 1996-07-11 CA CA002199032A patent/CA2199032A1/en not_active Abandoned
- 1996-07-11 CN CN96190898A patent/CN1166185A/zh active Pending
- 1996-07-11 KR KR1019970701601A patent/KR100222239B1/ko not_active IP Right Cessation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS53113214A (en) * | 1977-03-15 | 1978-10-03 | Nisshin Steel Co Ltd | Steel for nitriding use having high core hardness after nitriding treatment |
JPS5576046A (en) * | 1978-11-30 | 1980-06-07 | Nisshin Steel Co Ltd | Ultra low carbon nitriding steel |
JPH0280539A (ja) * | 1988-09-16 | 1990-03-20 | Nisshin Steel Co Ltd | 窒化用鋼素材 |
Non-Patent Citations (1)
Title |
---|
See also references of EP0778357A4 * |
Also Published As
Publication number | Publication date |
---|---|
CA2199032A1 (en) | 1997-01-30 |
EP0778357A1 (en) | 1997-06-11 |
CN1166185A (zh) | 1997-11-26 |
KR970706415A (ko) | 1997-11-03 |
KR100222239B1 (ko) | 1999-10-01 |
US5810948A (en) | 1998-09-22 |
EP0778357A4 (en) | 1998-12-23 |
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