CN1239729C - Economical air valve steel - Google Patents
Economical air valve steel Download PDFInfo
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- CN1239729C CN1239729C CN 200410037808 CN200410037808A CN1239729C CN 1239729 C CN1239729 C CN 1239729C CN 200410037808 CN200410037808 CN 200410037808 CN 200410037808 A CN200410037808 A CN 200410037808A CN 1239729 C CN1239729 C CN 1239729C
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Abstract
The present invention belongs to the field of preparing austenitic heat resistance steel, and particularly relates to an economical austenitic heat-resistance steel suitable for producing exhaust valves of an internal combustion engine. The air valve steel has the specific chemical composition contents with the weight percentage: 0.40 to 0.65% of C, not higher than 0.50 % of Si, 8.0 to 11.0 % of Mn, not higher than 0.030 % of S, not higher than 0.040 % of P, 19.0 to 23.0 % of Cr, 1.0 to 3.0 % of Ni, 0.20 to 1.10 % of Nd, 0.01 to 0.2 % of Re, 0.35 to 0.60 % of N and the balance of Fe. Compared with the steel in the prior art, the economical austenite air valve steel has the characteristics of reasonable composition design, good comprehensive performance, low preparing cost, etc. Because necessary adjustment is implemented on the composition design of the air valve steel, the steel has good oxidation resistance and combustion air corrosion resistance in the working range of 650 to 750 DEG C.
Description
Affiliated field
The invention belongs to the preparation field of Austenitic high temperature steel.Be specially adapted to produce the economical inlet and outlet valve austenitic heat-resistance steel of oil engine.
China is in the oil engine of moderate duty at present, be generally to adopt in 21-4N steel (the being 5Cr21Mn9Ni4N) conduct, the exhaust valve steel of little cylinder diameter, the working temperature of this steel is between 650-750 ℃, air valve steel life-time service at high temperature then has the stratiform amount of separating out and increases, because this lamellated separating out is the carbide and the nitride of chromium, therefore a large amount of precipitates can make the poor chromium of air valve steel matrix, cause the corrosion resistance of this steel under the high-temperature fuel gas condition significantly to descend, also can make the neck of air valve, dish portion, the dish conical surface forms corrosion pit, make the air valve steel produce gas leakage and dish portion cracking easily, the corrosion pit of air valve neck is easy to produce fatigue cracking even fracture under the effect of bending fatigue stress.The data introduction is also arranged in the prior art abroad, the air valve steel introduced of United States Patent (USP) 4929419 documents for example, this steel is the composition adjustment of carrying out at the 23-8N steel, as adopt and add the use properties that V, B, W, Mo element and raising C, N content change steel grade, though this steel performance slightly increases than 23-8N, but its manufacturing cost exceeds much than 21-4N, and this steel is to use the exhaust valve for internal combustion engine steel at the preparation high loading.What Germany was introduced in patent documentation DE 3704473 A1 in addition is a kind of modified version air valve steel, this steel is to have added 5-6%Al, 1.8-2.5%Nb, 0.8-1.5%W on 21-4N base steel plinth, N brings up to the composition range of 0.4-0.6%, this steel is to use in the exhaust valve for internal combustion engine of high loading, but the preparation cost of this steel still is higher than more than a times of 21-4N steel.Have the technology of improving shape air valve steel to also have Russian SU 1650762 A1 patents again, this patent documentation has been introduced and has a kind ofly been added 0.5-1.5%Mo on the 21-4N basis; 0.5-1.5%Nb; 0.5-1.5%V and 0.05-0.20%Zr element, the purposes performance of this steel will be higher than 21-4NWNb (X50CrMnNiNbN 219) steel, this steel is to use the vent valve in high load engine, its hot strength, creep rupture strength, hot hardness all are higher than X50CrMnNiNbN 219 steel, and its preparation cost is also at more than a times of 21-4N steel.
The clear 61-227154 document of Japanese Patent in the technology has also been introduced the Heat resisting cast steel that a kind of Cr-Mn is abroad, and the embodiment of this patent cast steel is 0.33-0.37C; 1.08-1.14Si; 11.64-13.03Mn; 0-2.34Ni; 25.06-26.04Cr; 1.36-2.08Nb; 0.21-0.43N; All the other are Fe.The Heat resisting cast steel of this patent introduction is to use the structure foundry goods such as oven inner liner plate at 800-1000 ℃, from the composition analysis of this cast steel is to belong to the material that is not suitable for preparing distressed structure spare, also do not belong to the material range of choice of air valve, and the preparation cost of this cast steel is also very high with high temperature steel.
Goal of the invention and content
It is reasonable in design to the objective of the invention is to propose a kind of composition, the economical austenitic air valve steel that good combination property and preparation cost are low.
According to purpose of the present invention, the economical austenitic air valve steel that we proposed also is that the 21-4N steel is the basis, reasonably adjusts by the composition to this steel, make air valve steel of the present invention when possessing good over-all properties, also reduced the preparation cost of this steel.The solution of economical austenitic air valve steel of the present invention at first is the deficiency at the 21-4N steel, and we redesign the composition of economical air valve steel.Can see that after the composition of steel of the present invention and 21-4N steel compares we increase and adjusted the content of Nb, Re and elements such as Ni, C, N in composition, purpose is to make original 21-4N steel only to rely on C, N, Cr in conjunction with changing mutually of forming.The present invention has formed new phase structure by the content that increases new element and adjust other elements, thereby suppresses and changed original Cr to separate out with the stratiform of C, N formation.After the timeliness of air valve steel of the present invention through 750 ℃ and 100 hours, the stratiform amount of separating out<10%, the stratiform amount of separating out of 21-4N steel is then>40%; And the structure of cenotype is more stable, and the yield strength after the long-time timeliness of high temperature, creep rupture strength and hot bending fatigue strength are apparently higher than 21-4N.In addition, because the increase of constituent contents such as Nb and Re all increases the anti-oxidant and anti-exhaust gas corrosion performance of air valve steel of the present invention in 650-750 ℃ of scope.The crystal grain of material is by refinement rationally.Therefore, the concrete chemical composition content weight % of economical austenitic air valve steel of the present invention is: C 0.40-0.65%; Si≤0.50%; Mn 8.0-11.0%; S≤0.030%; P≤0.040%; Cr 19.0-23.0%; Ni 1.0-3.0%; Nb 0.20-1.10%; Re 0.01-0.2%; N0.35-0.60%; All the other are Fe.In air valve composition of steel proposed by the invention, consider that at first this steel is guaranteeing that it has under the preceding topic of good over-all properties, by the reasonable adjustment of composition and constituent content, the preparation cost of air valve steel of the present invention is decreased, so our consideration when composition designs is as described below.Adding C and N element in the composition of air valve steel of the present invention, consider that mainly C and N are austenizer, is again the element that strengthen in the gap, and C and N and Cr, Nb can form carbide and carbonitride, can effectively improve strengthening effect.When the reasonable raising along with C, N content, the timeliness intensity effect of its material can be more remarkable, can guarantee that like this steel of the present invention at high temperature has enough high temperature, short time intensity and hot strength when long.In the composition of air valve steel of the present invention, add the Cr element, be to guarantee to have good anti-oxidant and anti-gas high-temperature corrosive nature in this steel, Cr and C, N chemical combination form compound, thereby not only improved intensity but also improve hardness and improve wear resistance, but add too much Cr element and then can help ferritic generation, or the generation of σ phase, this is unfavorable at reduction preparation cost and raising over-all properties to steel of the present invention, therefore must control the addition of Cr.Mn is an austenizer, and Mn can substitute Ni, thereby reduces the cost of steel, and the effect of Mn also is to help to increase the solid solution effect of N element in the matrix, and Mn also helps to suppress the effect that stratiform is separated out simultaneously.But the increase of Mn can reduce the anti-oxidant and anti-exhaust gas corrosion performance of steel, and Mn can also combine the back with the S in the steel and form MnS, thereby it is minimum that the deleterious effect of S is dropped to, thus the add-on of Mn element be chosen in the 8-11% scope more suitable.Nb is the important element that strong carbide forms, especially in ag(e)ing process, form stable secondary precipitate with C, N, Cr, this secondary precipitate has characteristics such as size is little, distribution disperse, hot strength and hot hardness also have active effect to crystal grain thinning simultaneously in the time of improving material long significantly.The Ni element also is the element that austenite forms, and the hot strength and the oxidation-resistance of steel also had effect significantly.The Si element is comparatively favourable to the oxidation-resistance and the anti-exhaust gas corrosion that improve steel, but the plastic property of steel is had adverse influence, so in steel of the present invention, should be controlled at≤0.5%.After in the composition of air valve steel of the present invention, adding rare earth element, can effectively improve the form of inclusion, make that the form of remaining inclusion is rendered as spherical in the steel, rare earth element can also improve the existence of crystal boundary place harmful element significantly in addition, with the oxidation-resistance that significantly improves steel, also play a role to stoping grain growth.Steel of the present invention is to be base with Fe, may have some inevitable tramp elements and bring in the steel in preparation process, has good comprehensive use properties in order to guarantee this steel, so should eliminate and control sneaking into of harmful element when steel-making as far as possible.
The preparation of economical austenitic air valve steel of the present invention is similar to the method for prior art, this steel can be made steel, cast and forge in the AOD stove or in other smelting furnaces, after adopting 800 milling train hot rollings to be shaped earlier to this ingot then, become to set the work in-process pole of size again in 650 mill millings.Blank after rolling will carry out the thermal treatment of annealing softening.Again through after slightly strong and essence is rectified, equipment such as employing coreless grinding machine carry out mechanical workout, and are prepared into the workpiece product that requires size to the blank after annealing.Product is that its detected result is all qualified by JB/T 6720 " metallographic examination of the oil engine inlet and outlet door " check that standard is carried out.
Economical austenitic air valve steel of the present invention is compared with the prior art steel, and it is reasonable in design to have a composition, characteristics such as good combination property and preparation cost are low.Because air valve steel of the present invention has been done necessary adjustment to composition design, makes this steel possess good anti-oxidant and anti-exhaust gas corrosion performance in 650-750 ℃ working range.The present invention is the austenitic heat-resistance steel that belongs to a kind of precipitation strength type, and this steel has the stratiform amount of separating out few (<5%), and mechanical property was higher than the 21-4N steel when high temperature was long, and cost is lower than a kind of novel economizer type air valve steel of 21-4N again.
Embodiment
Composition range according to economical air valve steel proposed by the invention, we have been five groups of embodiment of the present invention altogether, we have also done the 21-4N steel of one group of prior art simultaneously, and convenient for simultaneous test, the preparation of the economical air valve steel of the present invention is to adopt the preparation method similar to prior art.The composition contrast of embodiment of the invention air valve steel is listed in the table 1.The preparation of embodiment of the invention air valve steel is to adopt to smelt in the induction furnace of 50Kg and be cast into ingot, forging into test rod then, opening and forging temperature is 1160 ℃, final forging temperature should be not less than 1000 ℃, and then adopts the preparation method of prior art that the standard test specimen that coupon is processed into detection usefulness is tested.Embodiment of the invention product sample room temperature and pyritous mechanical property comparing result are listed in the table 2, listed content is the comparing result of embodiment of the invention product sample at 725 ℃ enduring quality (sample fracture time) in table 3, listed content is the comparing result of embodiment of the invention product standard specimen at 750 ℃ hot bending fatigue property in table 4, and listed content is embodiment of the invention product comparing result of the stratiform amount of separating out (%) after the timeliness in the time of 750 ℃ long in table 5.In following each table, sequence number 1-5 is an air valve steel of the present invention; Sequence number 21-4N steel is the prior art compared steel.
Think according to table 2, table 3, table 4 aggregation of data in the embodiment of the invention, though the room temperature of air valve steel of the present invention and high temperature, short time intensity and plasticity are suitable with 21-4N, and high temperature when long intensity such as creep rupture strength and hot bending fatigue strength therefore prove that steel of the present invention obviously is better than 21-4N at aspect of performance all apparently higher than 21-4N.And steel of the present invention stratiform amount of separating out after the timeliness in the time of 750 ℃ long significantly is lower than 21-4N (seeing Table 5) again, and corrosion resistance is much better than correlated 21-4N again.
The composition contrast of table 1 air valve steel of the present invention embodiment and prior art steel
The element sequence number | C | Si | Mn | S | P | Cr | Ni | N | Nb | Re | Fe |
21-4N | 0.56 | 0.12 | 8.42 | 0.008 | 0.028 | 21.36 | 3.85 | 0.41 | - | - | Surplus |
1 | 0.53 | 0.30 | 8.75 | 0.012 | 0.022 | 21.40 | 2.30 | 0.42 | 0.23 | 0.020 | Surplus |
2 | 0.56 | 0.26 | 8.77 | 0.013 | 0.024 | 21.25 | 2.25 | 0.43 | 0.45 | 0.025 | Surplus |
3 | 0.52 | 0.28 | 8.75 | 0.011 | 0.026 | 21.27 | 2.21 | 0.40 | 0.66 | 0.022 | Surplus |
4 | 0.54 | 0.28 | 8.76 | 0.012 | 0.024 | 21.10 | 2.20 | 0.47 | 0.90 | 0.022 | Surplus |
5 | 0.53 | 0.26 | 8.70 | 0.013 | 0.023 | 21.15 | 2.26 | 0.50 | 1.10 | 0.026 | Surplus |
The comparison of table 2 embodiment of the invention room temperature and mechanical behavior under high temperature (1150 ℃ of 30min W.C./750 ℃ 2h A.C.)
Table 3 embodiment of the invention is in the comparison (1150 ℃ of 30min W.C./760 ℃ 2h A.C.) of 725 ℃ of enduring qualities
Stress MPa | 21-4N | 1 # | 2 # | 3 # | 4 # | 5 # |
200 | 69h | 105h | 154h | 198h | 175h | 325h |
170 | 156h | 243h | 469h | 460h | 875h | 838h |
140 | 284h | 890h | 1200h | 1190h |
21-4N steel 1000h creep rupture strength is 110Mpa in ISO 683-15 and the DIN/EN10090 standard.(sample fracture time)
Table 4 embodiment of the invention contrasts (1150 ℃ of 60min W.C./760 ℃ 4h A.C.) at 750 ℃ of hot bending fatigue propertys
Stress MPa | 21-4N | 1 # | 2 # | 3 # | 4 # | 5 # |
360 | 3.03×10 6 | 6.75×10 6 | 1.14×10 7 | 1.09×10 7 | 1.23×10 7 | 1.32×10 7 |
Table 5 embodiment of the invention is the comparison (%) of the stratiform amount of separating out after the timeliness in the time of 750 ℃ long
The time sequence number | 2h | 10h | 30h | 60h | 100h | 200h |
21-4N | <5 | ~5 | 10~15 | 30~40 | 40~60 | 60~80 |
1 | ~1 | 1~2 | <5 | ~8 | <10 | <10 |
2 | ~1 | 1~2 | <5 | ~5 | <8 | <10 |
3 | ~1 | 1~2 | <3 | <5 | <5 | <8 |
4 | <1 | 1~2 | <3 | <5 | <5 | <5 |
5 | <1 | 1~2 | <3 | <3 | <5 | <5 |
Claims (1)
1, a kind of Eco-power austenite air valve steel is characterized in that the concrete chemical composition content weight % of this air valve steel is: C 0.40-0.65%; Si≤0.50%; Mn 8.0-11.0%; S≤0.030%; P≤0.040%; Cr 19.0-23.0%; Ni 1.0-3.0%; Nb 0.20-1.10%; Re 0.01-0.2%; N0.35-0.60%; All the other are Fe.
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CN 200410037808 CN1239729C (en) | 2004-05-10 | 2004-05-10 | Economical air valve steel |
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CN 200410037808 CN1239729C (en) | 2004-05-10 | 2004-05-10 | Economical air valve steel |
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CN1239729C true CN1239729C (en) | 2006-02-01 |
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Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
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CN1306053C (en) * | 2005-03-10 | 2007-03-21 | 钢铁研究总院 | High performance nickel saving gas valve alloy material |
CN100450651C (en) * | 2007-04-04 | 2009-01-14 | 江苏申源特钢有限公司 | Method for producing cogging by air-valve steel rolling |
CN102409257B (en) * | 2010-09-21 | 2013-05-29 | 宝山钢铁股份有限公司 | Austenite-series heat-resistant steel and manufacturing method thereof |
CN102921721B (en) * | 2012-10-26 | 2015-06-03 | 宝钢特钢有限公司 | Production method of ingot casting rolling cogging for steel for high load engine vent valve |
CN109112407B (en) * | 2018-09-21 | 2019-07-23 | 江西樟树市兴隆特殊钢有限公司 | A kind of high-performance Valve Steel and preparation method |
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