CN101537484A - Method for improving temperature distribution in process of single crystal casting solidification - Google Patents

Method for improving temperature distribution in process of single crystal casting solidification Download PDF

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Publication number
CN101537484A
CN101537484A CN200910030213A CN200910030213A CN101537484A CN 101537484 A CN101537484 A CN 101537484A CN 200910030213 A CN200910030213 A CN 200910030213A CN 200910030213 A CN200910030213 A CN 200910030213A CN 101537484 A CN101537484 A CN 101537484A
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heat conductor
single crystal
graphite
casting
temperature distribution
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CN200910030213A
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CN101537484B (en
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赵玉涛
马德新
孙少纯
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Jiangsu University
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Jiangsu University
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Abstract

The invention discloses a method for improving temperature distribution in a process of single crystal casting solidification, relating to the field of high-temperature alloy directional solidification. In a process of preparing molten mould casting ceramic mould shell, and in a process of implanting a heat conductor into a casting to be solidified and transfer heat to the external, a position with thermal barrier is easy to occur. The heat conductor is graphite or SiC. Practical use shows that by applying the technology, an undercooling difference and an undercooling time difference in the casting can be greatly reduced, thereby the probability of generating stray crystals is obviously reduced, and the single crystal qualified rate of the casting is greatly enhanced.

Description

A kind of method of improving Temperature Distribution in the process of single crystal casting solidification
Technical field
The present invention relates to high temperature alloy directional solidification field, refer in particular to a kind of method of improving Temperature Distribution in the process of single crystal casting solidification.
Background technology
From eighties of last century fifties, for function and the efficient that improves aero-engine, people successfully utilize the high temperature alloy directional solidification technique that turbine blade is made the monocrystalline form.Owing to eliminated the weak link under this hot operation condition of crystal boundary, made the hot operation life-span of blade improve tens times.Recent two decades comes, urgent day by day along with the energy and environmental protection problem, and each industrialized country all is being devoted to improve the especially efficient of power station gas turbine of industry gas turbine.Wherein most important measure is exactly that the single crystal blade technology of aero-engine is applied in the blade manufacturing of large scale industry gas turbine.Because the blade dimensions of gas turbine is much larger than aerial blade, weight has increased by tens times, makes the production of its single crystal casting become very difficult.The formation of external crystalline substance mostly occurs at the position of blade profile generation strong variations, and as our department of blade junction to integral shroud, sectional dimension generally all can have tens millimeters expansion.Integral shroud edge (B place in the accompanying drawing 1) because the thin radiating condition of formwork is good, can be cooled to liquidus temperature (T very soon L) below, cause the cold excessively of solution; And integral shroud interior angle (A place in the accompanying drawing 1), because the radiating condition extreme difference can keep superheat state for a long time.This thermal center point has hindered the expansion of the crystal growth of blade our department to B place, integral shroud edge, makes that the degree of supercooling at B place is increasing, finally causes the forming core and the growth of second crystal grain, has destroyed the monocrystalline of whole blade.Therefore,, improve the Temperature Distribution in the oriented monocrystalline casting solidification process by adjusting the radiating condition of outside formwork, for preventing that stray crystal from appearring in the part, most important.
Summary of the invention
The purpose of this invention is to provide a kind of method that can effectively improve Temperature Distribution in the process of single crystal casting solidification.
A kind of by implanting heat conductor, improve the method for Temperature Distribution in the single crystal casting directional solidification process.In the process of preparation model casting ceramic shell mould, heat conductor is implanted to casting solidification in outside diabatic process, be prone to the position of thermal boundary.Above-mentioned heat conductor is graphite or SiC, and the capacity of heat transmission of graphite exceeds tens times than ceramic shell mould, has the good high-temperature performance under vacuum condition, and the casting of high temperature alloy and to solidify all be to finish under the condition of vacuum.The graphite low price is easy to be processed into needed shape in addition.SiC also can be used as heat conductor, but its hardness height is difficult for processing.
The concrete grammar that heat conductor is implanted is: after molten (wax) mould surface first or second layer ceramic case form, heat conductor is bonded in the precalculated position with making shell with ceramic size; By the same preparation method of common precise casting mould shell, hang coating, stucco, the long-pending sand of heat conductor outer end is erased after having spread sand; When heat conductor is graphite, the ceramic shell mould roasting is needed to carry out in airtight sintering furnace, place graphite scrap in the sintering furnace to absorb oxygen.Or adopt following sintering method: formwork 600 ℃ of presintering earlier thoroughly dewax, and casting is preceding carries out 1200 ℃ of heat preservation sinterings of 1 hour earlier when vacuum is solidified in the stove preheating formwork, and then are heated to predetermined preheat temperature and cast; When adopting the SiC heat conductor in the formwork preparation process, to implant, can carry out the ceramic shell mould roasting by normal method.
When adopting the graphite heat conductor, also can adopt following method: before the implantation, on the graphite heat conductor, be coated with one deck cere.In the dewaxing process, the taking-up that comes off of cere melting heat conductor stays the hole in the position of original heat conductor; By after the normal method roasting, again the graphite heat conductor is glued in the hole with ceramic size then.
Principle of the present invention is promptly implanted the Effect on Temperature Distribution of heat conductor to foundry goods in the formwork, as shown in Figure 1.Among the figure: 1, ceramic shell mould; 2, hot-zone; 3, thermal baffle; 4, cold-zone; 5, heat conductor.Fig. 1 (a) is that the interior temperature field of ceramic shell mould of not implanting heat conductor usually distributes, and Fig. 1 (b) is the Temperature Distribution behind the implantation heat conductor.Obviously by implanting a heat carrier, the heat at integral shroud interior angle A place in time can be shed, it is cooled to below the liquidus temperature rapidly.The crystal growth of blade our department can enter integral shroud rapidly and to the expansion of outer rim B place, avoid herein because of the cold stray crystal that produces of long-time mistake.
Advantage of the present invention is: concrete application implementation is simple, need not to change original apparatus for directional solidification; By the heat at heat conductor derivation heat conduction thermal boundary place, can effectively regulate and optimize temperature field distribution in the process of single crystal casting solidification, guarantee the smooth growth and the expansion of monocrystalline.
Description of drawings
Fig. 1: implant the influence that heat conductor distributes to casting temperature in the formwork
(e) temperature field of not implanting single product blade foundry goods in the ceramic shell mould of heat conductor distributes, thereby visible obviously integral shroud outer rim B position easily forms isolated high undercooling district initiation stray crystal;
(f) implant the Temperature Distribution of single crystal blade foundry goods behind the heat conductor, the heat that obviously uses the heat conductor technology can alleviate the A position is greatly concentrated, thus make monocrystalline can the integral shroud outer rim reach the degree of depth cross cold before, expand to this place.
Fig. 2: the geometry of blade and the structure of ceramic shell mould
Fig. 3: implant heat conductor to T L-isothermal influence
When (a) not implanting heat conductor, solidification front T L-Isothermal Line Distribution
(b) behind the implantation heat conductor, solidification front T L-Isothermal Line Distribution
Fig. 4: implant the influence of heat conductor to the single crystal blade tissue
When (c) not implanting heat conductor, the both macro and micro tissue of blade body and integral shroud join domain
When (d) implanting heat conductor, the both macro and micro tissue of blade body and integral shroud join domain
1, ceramic shell mould, 2, the hot-zone, 3, thermal baffle, 4, the cold-zone, 5, heat conductor
The specific embodiment
Embodiment:
The technology of the present invention is applied to the casting of a single crystal blade, and length of blade is 150mm, and material is CMSX6, and the structure of ceramic shell mould is seen accompanying drawing 2.
Accompanying drawing 3 is in the process of setting of practical measurement in the ceramic shell mould, t1=2105s and t2=2190s T constantly L-Isothermal Line Distribution.Wherein (a) figure is not for implanting heat conductor, the T in the ceramic shell mould in the process of setting L-thermoisopleth; (b) figure implants under the heat conductor condition T in the ceramic shell mould in the process of setting L-thermoisopleth.Obviously as seen, liquidus curve (T L) thermoisopleth is because the effect of heat conductor becomes obviously mild by spill.The degree of supercooling at edge is reduced to 18 ℃ by 29 ℃, crosses cool time and is reduced to 150 seconds by 244 seconds, makes the possibility that forms second crystal grain herein reduce greatly.
Accompanying drawing 4 is for implanting and do not implant heat conductor gained blade foundry goods, the contrast of the both macro and micro tissue of blade body and integral shroud join domain.When not implementing the heat conductor technology, blade is actually the polycrystalline tissue in this zone, promptly stray crystal occurred at the integral shroud edge; And after the enforcement present technique, blade is a single crystal organization.Before using technology of the present invention, the single crystal blade foundry goods of being cast only is 20% in this position single crystal organization qualification rate; And the blade foundry goods of being produced behind the installation heat conductor is all qualified at the single crystal organization at this position.
As seen, use technology of the present invention, can effectively improve the radiating condition of integral shroud interior angle, make the crystal growth of blade our department in time expand to the integral shroud edge, thereby avoided the integral shroud part to generate stray crystal too greatly, improved the qualification rate of monocrystalline product greatly because of degree of supercooling.

Claims (5)

1, a kind of method of improving Temperature Distribution in the process of single crystal casting solidification, be specially: after molten (wax) mould surface first or second layer ceramic case form, heat conductor is bonded in casting solidification is prone to thermal boundary in outside diabatic process position with the system shell with ceramic size, and heat conductor is graphite or SiC; By the same preparation method of common precise casting mould shell, hang coating, stucco, spread behind the sand and to have carried out sintering after the long-pending sand of heat conductor outer end erased.
2, the described a kind of method of improving Temperature Distribution in the process of single crystal casting solidification of claim 1 is characterized in that: when heat conductor is graphite, the ceramic shell mould roasting is needed to carry out in airtight sintering furnace, place graphite scrap in the sintering furnace to absorb oxygen.
3, the described a kind of method of improving Temperature Distribution in the process of single crystal casting solidification of claim 1, it is characterized in that: when heat conductor is graphite, adopt following sintering method: formwork 600 ℃ of presintering earlier thoroughly dewax, before the casting when vacuum is solidified in the stove preheating formwork, carry out 1200 ℃ of heat preservation sinterings of 1 hour earlier, and then be heated to predetermined preheat temperature and cast.
4, the described a kind of method of improving Temperature Distribution in the process of single crystal casting solidification of claim 1 is characterized in that: when heat conductor is SiC, carry out the ceramic shell mould roasting according to a conventional method.
5, a kind of method of improving Temperature Distribution in the process of single crystal casting solidification is specially: when selecting for use graphite to be heat conductor, adopt following method: the implantation casting solidification is prone to the position of thermal boundary in outside diabatic process before, be coated with one deck cere on the graphite heat conductor; In the dewaxing process, the taking-up that comes off of cere melting heat conductor stays the hole in the position of original heat conductor; According to a conventional method after the roasting, again the graphite heat conductor is glued in the hole with ceramic size then.
CN2009100302138A 2009-03-17 2009-03-17 Method for improving temperature distribution in process of single crystal casting solidification Expired - Fee Related CN101537484B (en)

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101954452A (en) * 2010-10-14 2011-01-26 安徽应流集团霍山铸造有限公司 Shell manufacture method for solving problem on local shrinkage of precise investment casting alloy
CN102019354A (en) * 2010-12-27 2011-04-20 沈阳黎明航空发动机(集团)有限责任公司 Directional solidification method of ultra-thin and long shrouded blade
CN102166643A (en) * 2011-03-30 2011-08-31 江苏中欧材料研究院有限公司 Method for preventing monocrystal blades from having mixed crystal defects
CN102865944A (en) * 2012-09-03 2013-01-09 中国科学院金属研究所 Method for evaluating temperature field distribution in orientated solidification process
CN103147120A (en) * 2013-04-01 2013-06-12 东方电气集团东方汽轮机有限公司 Directional solidification device of high-temperature alloy
CN103192062A (en) * 2013-04-01 2013-07-10 东方电气集团东方汽轮机有限公司 Mold case for producing high-temperature alloy single crystal blades
CN103894546A (en) * 2014-03-26 2014-07-02 东方电气集团东方汽轮机有限公司 Precision casting method for complex casting with concave-convex end
CN104259442A (en) * 2014-09-29 2015-01-07 江苏大学 Method for preventing single crystal blade from generating miscellaneous crystal defect
CN104439077A (en) * 2014-12-15 2015-03-25 东方电气集团东方汽轮机有限公司 Wax tree structure for forming high-temperature alloy single-crystal turbine blade
CN104690256A (en) * 2015-02-11 2015-06-10 西北工业大学 Directional solidification method for controlling foreign crystal defects of nickel-base superalloy step cast
CN105772633A (en) * 2015-12-28 2016-07-20 浙江亚辰新材料科技有限公司 Mold filling device for directional solidification of turbine blades and preparation method
CN105964991A (en) * 2016-05-23 2016-09-28 西北工业大学 Directional solidification method capable of eliminating spots in casting
CN106563773A (en) * 2016-10-19 2017-04-19 江苏大学 Method for preventing mixed crystal defect of single crystal blade based on laser heating technology
CN106734852A (en) * 2016-12-22 2017-05-31 中国科学院金属研究所 A kind of anti-sticking tin liquid metal cools down the preparation method of directional solidification ceramic shell
CN107377879A (en) * 2017-08-29 2017-11-24 安徽信息工程学院 A kind of model casting casting method
CN108097877A (en) * 2017-11-02 2018-06-01 江苏大学 A kind of method for being used to inhibit monocrystal blades from having mixed crystal defects formation
CN110083927A (en) * 2019-04-24 2019-08-02 西安交通大学 It is a kind of for controlling the integrated cast design method of single crystal blade listrium stray crystal
CN114130994A (en) * 2021-12-20 2022-03-04 成都航宇超合金技术有限公司 Device and method for reducing mixed crystal defects at platform of single crystal blade

Cited By (26)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101954452A (en) * 2010-10-14 2011-01-26 安徽应流集团霍山铸造有限公司 Shell manufacture method for solving problem on local shrinkage of precise investment casting alloy
CN102019354A (en) * 2010-12-27 2011-04-20 沈阳黎明航空发动机(集团)有限责任公司 Directional solidification method of ultra-thin and long shrouded blade
CN102019354B (en) * 2010-12-27 2012-11-07 沈阳黎明航空发动机(集团)有限责任公司 Directional solidification method of ultra-thin and long shrouded blade
CN102166643A (en) * 2011-03-30 2011-08-31 江苏中欧材料研究院有限公司 Method for preventing monocrystal blades from having mixed crystal defects
CN102166643B (en) * 2011-03-30 2013-07-24 江苏中欧材料研究院有限公司 Method for preventing monocrystal blades from having mixed crystal defects
CN102865944A (en) * 2012-09-03 2013-01-09 中国科学院金属研究所 Method for evaluating temperature field distribution in orientated solidification process
CN103147120A (en) * 2013-04-01 2013-06-12 东方电气集团东方汽轮机有限公司 Directional solidification device of high-temperature alloy
CN103192062A (en) * 2013-04-01 2013-07-10 东方电气集团东方汽轮机有限公司 Mold case for producing high-temperature alloy single crystal blades
CN103147120B (en) * 2013-04-01 2016-04-20 东方电气集团东方汽轮机有限公司 A kind of device for directionally solidifying of superalloy
CN103894546B (en) * 2014-03-26 2016-03-23 东方电气集团东方汽轮机有限公司 The casting method of the concavo-convex intricate casting in end
CN103894546A (en) * 2014-03-26 2014-07-02 东方电气集团东方汽轮机有限公司 Precision casting method for complex casting with concave-convex end
CN104259442A (en) * 2014-09-29 2015-01-07 江苏大学 Method for preventing single crystal blade from generating miscellaneous crystal defect
CN104439077A (en) * 2014-12-15 2015-03-25 东方电气集团东方汽轮机有限公司 Wax tree structure for forming high-temperature alloy single-crystal turbine blade
CN104690256A (en) * 2015-02-11 2015-06-10 西北工业大学 Directional solidification method for controlling foreign crystal defects of nickel-base superalloy step cast
CN105772633B (en) * 2015-12-28 2018-05-11 浙江亚辰新材料科技有限公司 A kind of turbo blade hot investment casting directional freeze method
CN105772633A (en) * 2015-12-28 2016-07-20 浙江亚辰新材料科技有限公司 Mold filling device for directional solidification of turbine blades and preparation method
CN105964991A (en) * 2016-05-23 2016-09-28 西北工业大学 Directional solidification method capable of eliminating spots in casting
CN106563773A (en) * 2016-10-19 2017-04-19 江苏大学 Method for preventing mixed crystal defect of single crystal blade based on laser heating technology
CN106563773B (en) * 2016-10-19 2018-06-26 江苏大学 A kind of method that monocrystal blades from having mixed crystal defects is prevented based on laser heating technique
CN106734852B (en) * 2016-12-22 2019-05-21 中国科学院金属研究所 A kind of preparation method of the cooling directional solidification ceramic shell of anti-sticking tin liquid metal
CN106734852A (en) * 2016-12-22 2017-05-31 中国科学院金属研究所 A kind of anti-sticking tin liquid metal cools down the preparation method of directional solidification ceramic shell
CN107377879A (en) * 2017-08-29 2017-11-24 安徽信息工程学院 A kind of model casting casting method
CN107377879B (en) * 2017-08-29 2019-10-11 安徽信息工程学院 A kind of model casting casting method
CN108097877A (en) * 2017-11-02 2018-06-01 江苏大学 A kind of method for being used to inhibit monocrystal blades from having mixed crystal defects formation
CN110083927A (en) * 2019-04-24 2019-08-02 西安交通大学 It is a kind of for controlling the integrated cast design method of single crystal blade listrium stray crystal
CN114130994A (en) * 2021-12-20 2022-03-04 成都航宇超合金技术有限公司 Device and method for reducing mixed crystal defects at platform of single crystal blade

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