CN102925831B - Preparation method for fine-grain magnesium alloy - Google Patents
Preparation method for fine-grain magnesium alloy Download PDFInfo
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- CN102925831B CN102925831B CN201210451142.0A CN201210451142A CN102925831B CN 102925831 B CN102925831 B CN 102925831B CN 201210451142 A CN201210451142 A CN 201210451142A CN 102925831 B CN102925831 B CN 102925831B
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Abstract
The invention discloses a preparation method for fine-grain magnesium alloy. The preparation method comprises the following steps: (1) a mold and a sample are respectively heated primarily, (2) after the temperature of the mold and the sample reaches the pre-heat temperature, the sample is placed into a grind instrument and is squeezed by means of a route of Bc, a back pressure of 50 MPa is exerted in the direction where the sample is squeezed, so that the sample is in a state of three-direction stress, (3) every time the sample is squeezed by two ways, the temperatures of the sample and the mold are both lowered by 20 DEG C, (4) the sample after being cooled is squeezed according to the step (2), if the sample cracks in the squeezing process, squeezing is stopped, and if the sample does not crack in the squeezing process, the squeezing of the next way is carried out, and (5) the step (3) and the step (4) are repeated until the sample cracks in the squeezing process. The preparation method for the fine-grain magnesium alloy is simple to operate, reliable and easy to popularize, and resolves the problems that the temperature is high in the process of plastic deformation of the magnesium alloy, and the refining of grains is not obvious.
Description
Technical field
The present invention relates to metal material processing technical field, relate in particular to a kind of preparation method of thin grained magnesium alloy.
Background technology
Magnesium alloy is one of the lightest structural metallic materials of current industrial application, other metallic substance relatively, magnesium alloy has low density, and specific tenacity and specific rigidity are high, the advantages such as good machinability, are having good application prospect aspect Aeronautics and Astronautics and automotive industry.In recent years, along with novel magnesium alloy material is in the quick application of Aeronautics and Astronautics, automobile and electron trade, the research of magnesium alloy has also been entered to a new stage, but magnesium alloy belongs to close-packed hexagonal structure, slip system is few, poor, the low wide range of industrial applications that restricts magnesium alloy of intensity of plasticity under normal temperature.The plasticity that adopts viscous deformation to improve magnesium alloy is the emphasis that people study always, and conventional extruded technique is to improve the performance of magnesium alloy, but grain refinement effect is limited, can not increase substantially the performance of magnesium alloy.The research that is introduced as magnesium alloy of large plastometric set technique (SPD) open up a new way [1-3], adopt large plastometric set technique can prepare ultrafine crystal deformed magnesium alloy, in addition, Mg-RE magnesium alloy is because rare earth element has stronger solution strengthening and precipitation strengthening effect, mechanical property is greatly improved compared with traditional magnesium alloy, becomes people's study hotspot.
Refined crystalline strengthening is the main schedule of reinforcement of magnesium alloy, although significantly crystal grain thinning of large plastometric set, grain size is more responsive to extrusion temperature, and magnesium alloy plasticity is bad.Equal Channel Angular Pressing (ECAP) is the effective large plastometric set technique of the one of crystal grain thinning [4], but has a problem, and ECAP must carry out at higher temperature, and no person there will be crackle, and under high temperature, crystal grain can be grown up, and thinning effect is bad.So probe under a kind of low temperature, to carry out the technique of large plastometric set to magnesium alloy significant.
Reference:
[1] CHEN YONGJUN, Wang Qudong, Zhai Chunquan, Ding Wenjiang. large plastometric set is prepared the Study prospects [J] of high-strength magnesium alloy. mechanical engineering material, 2006 (3), 1-3+47.
[2] Zhang Juan, Liu Changrui, Wang Kuaishe, Ren Hongxia. prepare the large plastometric set method [J] of block grained material. New Technologies, 2008 (8), 93-96+4.
[3] Du Wenbo, Qin Yaling, Yan Zhenjie, Zuo Tieyong. the impact [J] of large plastometric set on magnesium alloy microtexture and performance. Rare Metals Materials and engineering, 2009 (10), 1870-1875.
[4] Jin Li. Magnesium Alloy by Equal Channel Angular Extrusion microtexture and mechanical property research. Shanghai Communications University's Ph D dissertation, 2006.
Summary of the invention
The object of the invention is to solve above-mentioned deficiency of the prior art, for at higher temperature, while adopting Equal Channel Angular Pressing (ECAP) to prepare magnesium alloy, there is crackle, grain growth, the bad problem of thinning effect, a kind of preparation method of thin grained magnesium alloy is provided, described method applies certain back pressure to material in the time that material carries out ECAP, (three-dimensional is for horizontal in three-dimensional stress state to make material, longitudinally, normal direction), improve the plasticity of material, reduce the minimum extrusion temperature of material flawless extruding.There is crackle in material when preventing that extrusion temperature is too low in addition, and the present invention adopts multistep cooling.The present invention is applicable to cast magnesium alloys, is also applicable to the secondary deformation of wrought magnesium alloys, has both been applicable to traditional magnesium alloy, is applicable to again magnesium-rare earth, and for the magnesium-rare earth of difficulty distortion, effect is particularly evident especially.
For achieving the above object, the invention provides a kind of preparation method of thin grained magnesium alloy, specifically comprise the following steps:
(1) respectively mould and sample are carried out to preheating;
(2) arrive after preheating temperature until described mould and described specimen temperature, described sample is put into described grinding tool, adopt Bc route to push, in the direction being extruded at described sample, apply 50Mpa back pressure, make described sample in three-dimensional stress state;
(3) after every extruding 2 passages, the temperature of described sample and described mould is all reduced to 20 DEG C;
(4) sample after described cooling, pushes by step (2), as described in sample time there is crackle in extruding, stop extruding; As described in sample in extrusion process, there is not crackle, carry out lower a time extruding;
(5) repeating step (3) and step (4) until there is crackle in described sample in the time of extruding.
Further, described mould is for waiting passage extrusion mould.
Further, described grinding tool adopts heating collar heating, and described sample heats in holding furnace.
Further, described sample comprises magnesium-rare earth and non-magnesium-rare earth.
Further, described sample is magnesium-rare earth, and the mould that step (1) is described and the preheating temperature of sample are 350-420 DEG C.
Further, described sample is non-magnesium-rare earth, and the mould that step (1) is described and the preheating temperature of sample are 200-250 DEG C.
Further, before described extruding, sample is of a size of 12mm × 12mm × 90mm.
Further, described Bc route is between adjacent passage, and sample rotates clockwise 90 °.
Further, the speed of described extruding is 12mm/s.
Further, the time of described extruding is 9s.
What the present invention adopted waits passage extrusion mould is the mould of the autonomous research in this laboratory and design, concrete referenced patent: the patent No.: 2012100833603, and the passage extrusion moulds such as a kind of back pressure.The present invention is compared with conventional extruded technique, and while adopting the extruding of Equal Channel Angular Pressing mould, mould and sample be heating separately, mould is by the heating collar heating of parcel die, and sample heats with holding furnace, and mould heated together with sample in the past, can only push a sample, mould efficiency is low at every turn; Equal Channel Angular Pressing mould is furnished with back pressure apparatus, by push rod mode, sample is applied to back pressure, and back pressure push rod can insert in transverse passage-way, in the time that being just extruded, sample just applies back pressure, can make sample stressed evenly, homogeneity of structure is better, in addition, sample is in the time of Equal Channel Angular Pressing, extruded sample is applied to back pressure, can effectively prevent germinating and the expansion of crackle, under back pressure effect, make sample in three-dimensional stress state, improved the plastic deformation ability of material; Adopt Bc extruding route, Bc route refers between adjacent passage (sample every extruding in mould once, is called a passage), sample rotates clockwise 90 °, compared with other route, after the extruding of Bc route multi-pass, the deformation uniformity of alloy is better; What the present invention lowered the temperature employing is multistep cooling, once temperature is fallen after every extruding 2 passages, along with the increase of extruded sample passage, the plasticity of material improves gradually, while cooling below, the plasticity of material makes moderate progress, and is difficult for cracking, and adopts multistep cooling, reduce extrusion temperature, be conducive to further crystal grain thinning.
Below with reference to accompanying drawing, the technique effect of design of the present invention, concrete structure and generation is described further, to understand fully object of the present invention, feature and effect.
Brief description of the drawings
Fig. 1 is the metallograph of GW103 magnesium-rare earth alloy before waiting passage extruding in the invention process 1.
Fig. 2 is that in the invention process 1, GW103 magnesium-rare earth, under 50MPa back pressure, pushes 1-2 passage at 420 DEG C, lowers the temperature, and pushes the metallograph of alloy after 3-4 passage at 400 DEG C.
Fig. 3 is that in the invention process 1, GW103 magnesium-rare earth is after 4 passage extruding, and extrusion temperature drops to 380 DEG C, applies 50MPa back pressure, after extruding 5-6 passage, and the metallograph of alloy.
Fig. 4 is the metallograph of alloy before the extruding of the passage such as the non-magnesium-rare earth of AZ31 in the invention process 2.
Fig. 5 is that in the invention process 2, the non-magnesium-rare earth of AZ31, under 50MPa back pressure, pushes 1-2 passage at 220 DEG C, lowers the temperature, and pushes the metallograph of alloy after 3-4 passage at 200 DEG C.
Fig. 6 is that in the invention process 2, the non-magnesium-rare earth of AZ31 is after 4 passage extruding, and extrusion temperature drops to 180 DEG C, applies 50MPa back pressure, after the extruding of 5-6 passage, and the metallograph of alloy.
Embodiment
Embodiment 1:
Adopting raw material is trade mark GW103 magnesium-rare earth, and alloying constituent: Gd is 10%; Y is 3%; Zr is 0.4%, and all the other are Mg, and ratio is mass percent.Concrete steps are:
1, GW103 magnesium-rare earth is cut into the extruded sample of 12mm × 12mm × 90mm.
2, adopt the heating collar that surrounds mould to carry out preheating to mould, by temperature controller control die temperature, mold preheating temperature is made as 420 DEG C.
3, the holding furnace temperature on hydropress side is made as to 420 DEG C, holding furnace temperature arrives after preset temp, and specimen surface is coated with one deck oildag, reduces the friction between sample and mould, and sample is put in holding furnace and heated.
4, in the time that mould and specimen temperature reach preset temp, sample takes out from holding furnace, puts into etc. in passage extrusion mould and pushes, and applies the back pressure that size is 50MPa when extruding at sample in the direction being extruded, extrusion speed is made as 12mm/s, extrusion time 9s.
5, under 50MPa back pressure, the passage extrusion moulds such as employing and Bc extruding route pushes 1-2 passage at 420 DEG C, lowers the temperature, and pushes 3-4 passage at 400 DEG C, then lowers the temperature, and temperature drops to 380 DEG C.
6, under 50MPa back pressure, the passage extrusion moulds such as employing and Bc extruding route, at 380 DEG C, carry out the extruding of 5-6 passage to sample, applies the back pressure of size for 50MPa in the direction that sample is extruded, and extrusion speed is made as 12mm/s, extrusion time 9s.
The present embodiment GW103 magnesium-rare earth is before process waits passage extruding, the metallograph of alloy as shown in Figure 1, the coarse grains of alloy, average particle size particle size 45 μ m left and right.GW103 magnesium-rare earth, through waiting after passage extruding, pushes 1-2 passage at 420 DEG C, lowers the temperature, and pushes after 3-4 passage at 400 DEG C, and as shown in Figure 2, the crystal grain of alloy obtains refinement to the metallograph of alloy, average particle size particle size 4.5 μ m left and right.GW103 magnesium-rare earth is after 4 passage extruding, and extrusion temperature drops to 380 DEG C, and after extruding 5-6 passage, as shown in Figure 3, crystal grain obtains further refinement to the metallograph of alloy, average particle size particle size 2.5 μ m left and right.
Embodiment 2:
Adopting raw material is the non-magnesium-rare earth alloy of trade mark AZ31, and composition: AL is 3%; Y is 3%; Zn is 1%, and all the other are Mg, and ratio is mass percent.Concrete steps are:
1, non-AZ31 magnesium-rare earth is cut into the extruded sample of 12mm × 12mm × 90mm.
2, adopt the heating collar that surrounds mould to carry out preheating to mould, by temperature controller control die temperature, mold preheating temperature is made as 220 DEG C.
3, the holding furnace temperature on hydropress side is made as to 220 DEG C, holding furnace temperature arrives after preset temp, and specimen surface is coated with one deck oildag, reduces the friction between sample and mould, and sample is put in holding furnace and heated.
4, in the time that mould and specimen temperature reach preset temp, sample takes out from holding furnace, puts into etc. in passage extrusion mould and pushes, and applies the back pressure that size is 50MPa when extruding at sample in the direction being extruded, extrusion speed is made as 12mm/s, extrusion time 9s.
5, under 50MPa back pressure, the passage extrusion moulds such as employing and Bc extruding route pushes 1-2 passage at 220 DEG C, lowers the temperature, and pushes 3-4 passage at 200 DEG C, continues cooling, and temperature drops to 180 DEG C.
6, under 50MPa back pressure, the passage extrusion moulds such as employing and Bc extruding route, at 180 DEG C, carry out the extruding of 5-6 passage to sample, and extrusion speed is made as 12mm/s, extrusion time 9s.
The non-magnesium-rare earth of the present embodiment AZ31 is before process waits passage extruding, the metallograph of alloy as shown in Figure 4, the coarse grains of alloy, average particle size particle size 27 μ m left and right.The non-magnesium-rare earth of AZ31 is through waiting after passage extruding, and it is 50MPa that institute adds back pressure, pushes 1-2 passage at 220 DEG C, lower the temperature, push 3-4 passage at 200 DEG C, the metallograph of alloy as shown in Figure 5, the crystal grain of alloy obtains refinement, average particle size particle size 10 μ m left and right.The non-magnesium-rare earth of AZ31 is after 4 passage extruding, and temperature drops to 180 DEG C, and after extruding 5-6 passage, as shown in Figure 6, crystal grain obtains further refinement to the metallograph of alloy, average particle size particle size 1.7 μ m left and right.
More than describe preferred embodiment of the present invention in detail.The ordinary skill that should be appreciated that this area just can design according to the present invention be made many modifications and variations without creative work.Therefore, all technician in the art, all should be in by the determined protection domain of claims under this invention's idea on the basis of existing technology by the available technical scheme of logical analysis, reasoning, or a limited experiment.
Claims (8)
1. a preparation method for thin grained magnesium alloy, is characterized in that specifically comprising the following steps:
(1) respectively mould and sample are carried out to preheating;
(2) arrive after preheating temperature until described mould and described specimen temperature, described sample is put into described mould, adopt Bc route to push, in the direction being extruded at described sample, apply 50Mpa back pressure, make described sample in three-dimensional stress state;
(3) after every extruding 2 passages, the temperature of described sample and described mould is all reduced to 20 DEG C;
(4) sample after described cooling, pushes by step (2), as described in sample time there is crackle in extruding, stop extruding; As described in sample in extrusion process, there is not crackle, carry out lower a time extruding;
(5) repeating step (3) and step (4) until there is crackle in described sample in the time of extruding;
The speed of described extruding is 12mm/s; The time of described extruding is 9s.
2. preparation method as claimed in claim 1, wherein, the described mould of step (1) is to wait passage extrusion mould.
3. preparation method as claimed in claim 1, wherein, described mould adopts heating collar heating, and described sample heats in holding furnace.
4. preparation method as claimed in claim 1, wherein, described sample is the one in magnesium-rare earth and non-magnesium-rare earth.
5. preparation method as claimed in claim 1, wherein, described sample is magnesium-rare earth, the mould that step (1) is described and the preheating temperature of described sample are 350-420 DEG C.
6. preparation method as claimed in claim 1, wherein, described sample is non-magnesium-rare earth, the mould that step (1) is described and the preheating temperature of described sample are 200-250 DEG C.
7. preparation method as claimed in claim 1, wherein, before described extruding, sample is of a size of 12mm × 12mm × 90mm.
8. preparation method as claimed in claim 1, wherein, described Bc route is between adjacent passage, sample rotates clockwise 90 °.
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| CN201210451142.0A CN102925831B (en) | 2012-11-12 | 2012-11-12 | Preparation method for fine-grain magnesium alloy |
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| CN104726804A (en) * | 2013-12-24 | 2015-06-24 | 上海交通大学深圳研究院 | Novel high-plasticity rare earth magnesium alloy preparation technology |
| CN104651694A (en) * | 2015-01-30 | 2015-05-27 | 上海交通大学 | Magnesium alloy and preparation method and application thereof |
| CN110468294A (en) * | 2019-09-23 | 2019-11-19 | 上海交通大学 | Mg in a kind of Mg-Al-Si system alloy2The thinning method of Si phase |
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