CN107190220B - A method of improving magnesium-rare earth fatigue behaviour using unusual twin - Google Patents

A method of improving magnesium-rare earth fatigue behaviour using unusual twin Download PDF

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Publication number
CN107190220B
CN107190220B CN201710366055.8A CN201710366055A CN107190220B CN 107190220 B CN107190220 B CN 107190220B CN 201710366055 A CN201710366055 A CN 201710366055A CN 107190220 B CN107190220 B CN 107190220B
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China
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twin
rare earth
magnesium
unusual
fatigue
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CN201710366055.8A
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Chinese (zh)
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CN107190220A (en
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杨续跃
肖振宇
霍庆欢
张笃秀
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中南大学
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/06Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of magnesium or alloys based thereon

Abstract

A method of improving magnesium-rare earth fatigue behaviour using unusual twin, the present invention carries out pre-treatment in 15~80 ° of direction in 15~300 DEG C of lower edges and basal plane normal direction to magnesium-rare earth, true strain amount is 0.0005~0.1, pass through the unusual twin of predeformation { 10 12 } preset into magnesium-rare earth, to whether there is or not the magnesium-rare earths of unusual twin to carry out testing fatigue, compared to the magnesium-rare earth of not preset unusual twin, the magnesium-rare earth fatigue limit of preset abnormality twin is obviously improved, fatigue life is extended, and fatigue behaviour is obviously improved.The present invention provides a kind of reasonable design, equipment requirement is simple and convenient to operate, is at low cost, is efficient, stablizes the technique for improving magnesium-rare earth fatigue behaviour.

Description

A method of improving magnesium-rare earth fatigue behaviour using unusual twin

Technical field

The present invention relates to a kind of methods improving magnesium-rare earth fatigue behaviour using unusual twin, and in particular to be one Kind improves the method for magnesium-rare earth fatigue behaviour by the preset unusual twin organization of regulation control of pre-treatment, belongs to non-ferrous metal Inactivation and protection for materials technical field.

Background technology

Magnesium-rare earth has broad application prospects in the fields such as the vehicles, aerospace.It is gradually replaced It is applied on automobile or aircraft as time bearing member even main load-bearing part for aluminium alloy.In recent years, although numerous countries and enterprise All input huge fund researchs and develops high tough rare earth magnesium alloy material to industry in succession, but compared to aluminium alloy, commercial application process Also be difficult to achieve the desired results, wherein cyclic loading when poor fatigue properties become one of the main bottleneck for limiting its application of being on active service. Different from ordinary magnesium alloy, the fatigue damage when fatigue damage of magnesium-rare earth, especially high all cyclic loadings is derived mainly from friendship A large amount of generations of sliding.Existing research utilizes the hands such as solid solution and ageing treatment mainly by continuing to increase the addition of rare earth element Section introduces precipitated phase and commutative Banach aglebra, the proportion of common magnesium-rare earth part middle rare earth is inhibited to be up to 12~18wt.%.However rare earth is first Element largely adds introduced precipitated phase, in the fatigue process middle and later periods due to stress concentration, can become crack initiation instead Source.It on the other hand, should be by the cycle profit of material in the high tough magnesium-rare earth composition design of selection, process optimization scheme With taking into account, key is to simplify alloying component and the trade mark, reduces harmful, rare and noble element addition.Meanwhile The addition for aggravating rare earth element not only increases alloy density, but also production cost increases.It is expected that research and development of magnesium alloy from now on Trend also will gradually be changed to attention " organization optimization technique " from traditional attention " ingredient and alloying ".Therefore, it is necessary to one kind Simply, tissue modulation technique that is at low cost, can effectively improve magnesium-rare earth fatigue behaviour and method promote magnesium-rare earth Military service application.

Invention content

Present invention aims at providing, a kind of technological design is reasonable, equipment requirement is simple and convenient to operate, at low cost, effective Improve the method for magnesium-rare earth fatigue behaviour.

In order to achieve the above object, a kind of method improving magnesium-rare earth fatigue behaviour using unusual twin of the present invention, Including:

Along basal plane easy glide direction at 15~300 DEG C, i.e., rare earth magnesium is closed in 15~80 ° of direction along with basal plane normal direction Gold carries out pre-treatment, and deflection determines by the yield point of the alloy, and true strain is 0.0005~0.1, by predeformation to { 10-12 } preset in magnesium-rare earth abnormality twin inhibits rare earth magnesium to close using the pinning effect of unusual twin On Dislocation Motion The commutative Banach aglebra of golden fatigue process Dislocations improves fatigue behaviour to improve fatigue limit, extend fatigue life;Described is anti- For often twin is relatively normal { 10-12 } twin, normal twin, which refers to, geometrically to be thought with crystal grain basal plane normal direction in 0 ° of stretching Or { 10-12 } twin generated when with it in 90 ° of compressions;And along with basal plane normal direction in 15~75 ° of direction to magnesium-rare earth When being stretched or being compressed, { 10-12 } twin of appearance is then { 10-12 } unusual twin.

A kind of method improving magnesium-rare earth fatigue behaviour using unusual twin of the present invention, the pre-treatment is to adopt With one kind or at least one processing mode in pre-stretching, compression, bending.

A kind of method improving magnesium-rare earth fatigue behaviour using unusual twin of the present invention, the predeformation temperature range 25~300 DEG C, 0.001~0.3s of predeformation speed range-1, predeformation amount determines that true strain is by the yield point of the alloy 0.002~0.05.

A kind of method improving magnesium-rare earth fatigue behaviour using unusual twin of the present invention, the load side of the predeformation To the direction that along the direction of basal plane easy glide, in particular to basal plane normal direction should be in 15~60 °.

A kind of method being improved magnesium-rare earth fatigue behaviour using unusual twin of the present invention, the magnesium-rare earth are selected from Mg-RE systems, Mg-RE-Zn systems alloy.

A kind of method being improved magnesium-rare earth fatigue behaviour using unusual twin provided by the invention is had following several big excellent Point:

1, present invention process is not necessarily to aggravate the addition of rare earth, it is preferred that emphasis is and to now organized regulation and control, suitable material is extensive, Environmental protection is at low cost, and production efficiency is high;Preset abnormality twin, equipment requirement letter in existing tissue in the way of simple small deformation It is single, easy to operate;

2, geometrically think the { 10- for stretching in 0 ° with crystal grain (0001) basal plane normal direction or being generated when compressing in 90 ° with it 12 } twin is normal { 10-12 } twin, and this normal twin leads to magnesium alloy work softening, unfavorable to fatigue behaviour;On the contrary, When with matrix basal plane normal direction in 15~75 ° of loads, no matter stretches or compress, basal plane all easy glides, normal twin is difficult to out It is existing, but be uneven shear strain caused by cooperative slip, it will appear in the crystal grain of these easy basal slips and do not follow { 10-12 } unusual twin of { 10-12 } normal twin condition;

3, unusual twin can effectively inhibit the commutative Banach aglebra of dislocation, lead to processing hardening, be conducive to promote yield stress, expand CYCLIC LOADING range;

4, precipitated phase and normal twin are compared, unusual twin is more preferable in tired stand under load process and the compatibility of matrix, energy Cause strain hardening, it is also relatively small to the damage of material matrix.

5, after the preset unusual twin of pre-treatment, the fatigue behaviour of magnesium-rare earth is promoted, and fatigue life increases, Fatigue limit intensity improves at least 50%.

In conclusion present invention process is reasonable, flow is simple, easy to operate, at low cost, efficient, to magnesium-rare earth Fatigue behaviour improvement wants more obvious, has a good application prospect.

Description of the drawings

Fig. 1 (a) is the distribution of orientations organized after the alloy hot rolled preset unusual twins of Mg-1.5Gd in the embodiment of the present invention 1 Figure;Fig. 1 (b) is alloy hot rolled (0001) basal plane pole figures containing unusual twin crystal grain of Mg-1.5Gd in the embodiment of the present invention 1;

Fig. 2 is that whether there is or not stress amplitude-cycles time that preset unusual twin Mg-1.5Gd is alloy hot rolled in the embodiment of the present invention 1 Number curve comparison diagram;

Fig. 3 (a) is that group after the preset unusual twin of state Mg-6Gd-3Y-1Zn-0.4Zr alloys is cast in the embodiment of the present invention 2 The distribution of orientations figure knitted;Fig. 3 (b) is Mg-6Gd-3Y-1Zn-0.4Zr alloys in the embodiment of the present invention 2 containing unusual twin crystal grain (0001) basal plane pole figure;

Fig. 4 is that whether there is or not preset unusual twins to cast answering for state Mg-6Gd-3Y-1Zn-0.4Zr alloys in the embodiment of the present invention 2 Power width-cycle-index curve comparison figure;

Fig. 5 (a) is the distribution of orientations figure organized after the alloy hot rolled preset unusual twins of Mg-2Y in the embodiment of the present invention 3; Fig. 5 (b) is alloy hot rolled (0001) basal plane pole figures containing unusual twin crystal grain of Mg-2Y in the embodiment of the present invention 3;

Fig. 6 (a) is that whether there is or not stress amplitude-cycles time that preset unusual twin Mg-2Y is alloy hot rolled in the embodiment of the present invention 3 Number curve comparison diagram;It is alloy hot rolled in the half-life that Fig. 6 (b) is that whether there is or not preset unusual twin Mg-2Y in the embodiment of the present invention 3 Stress-strain B-H loop comparison diagram.

Specific implementation mode

It is intended to further illustrate the present invention with reference to embodiments, is not intended to limit the present invention.

Embodiment 1

The present embodiment is that Mg-1.5Gd is alloy hot rolled using raw material.After 430 DEG C of homogenizing annealing 5h, average crystalline substance Particle size is about 120 μm.Crystal grain orientation is analyzed based on electron backscattered technology of spreading out, is chosen and is added according to distribution of orientations result Carry direction.At 300 DEG C, along pre-stretching processing is carried out to the test specimen with 15~60 ° of directions of basal plane normal direction angle, compression speed is 0.003s-1, dependent variable is about 0.005~0.05.

Shown in La Hou test specimens tissue orientating distribution map such as Fig. 1 (a), according to the criterion of unusual twin, contain twin crystal grain base (0001) basal plane pole figure of body is made and is divided to its region, and wherein LD (Loading Direction) is predeformation Loading stress direction (vertical paper direction), TD (Transverse Direction) are with loading direction in 90 ° of transverse direction, edge When LD stretchings, 1 is normal twin area, and 2 be unusual twin area, as shown in Fig. 1 (b).From Fig. 3 (b) it is found that loading direction and this (0001) basal plane normal direction angle of a little crystal grain is concentrated mainly on 15~60 °, meets 15~75 ° of unusual twin criterions, along this direction The twin occurred when stretching is unusual twin.It may determine that the twin occurred in these crystal grain is { 10-12 } unusual twin.

Its fatigue behaviour is tested at room temperature, gained stress amplitude-cycle-index curve comparison figure as shown in Fig. 2, Compare both stress amplitude-cycle-index curve it is found that it is preset abnormality twin Mg-1.5Gd alloy test specimens, in same stress amplitude Under cycle-index be greater than not preset unusual twin test specimen.Such as in the case where stress amplitude is the cyclic loading of 70MPa, preset abnormality Twin makes the fatigue life of test specimen be increased to from 140000 times 450000 times, promotes about 3 times or so.Meanwhile preset abnormality is twin After crystalline substance, the fatigue limit of test specimen has also been increased to 60MPa from 30MPa, promotes 100%.Preset abnormality twin can effectively improve it Fatigue behaviour.

Embodiment 2

The present embodiment is casting state Mg-6Gd-3Y-1Zn-0.4Zr alloys using raw material.Average grain size is about 60 μ m.At 25 DEG C, 0.03s-1Under along with 15~60 ° of directions of basal plane normal direction angle to the test specimen carry out precompression treatment, dependent variable is about It is 0.01~0.03.

The crystal grain orientation of test specimen after stretching is analyzed based on electron backscattered technology of spreading out, obtains distribution of orientations Fig. 3 (a), (0001) basal plane pole figure containing twin grain matrix is made and its region is divided, compressed along the directions LD After (vertical paper direction) pre-treatment, 3 be normal twin area, and 4 be unusual twin area, as shown in Fig. 3 (b).From Fig. 3 (b) It is found that (0001) basal plane normal direction angle of loading direction and these crystal grain is concentrated mainly at 15~60 °, meet 15~75 ° instead Normal twin criterion, the twin occurred when being compressed along this direction are unusual twin.

Its fatigue behaviour is tested at room temperature, gained stress amplitude-cycle-index curve comparison figure as shown in figure 4, Compare both stress amplitude-cycle-index curve it is found that it is preset abnormality twin Mg-6Gd-3Y-1Zn-0.4Zr alloy test specimens, Cycle-index under same stress amplitude is greater than not preset unusual twin test specimen.Meanwhile after preset unusual twin, test specimen it is tired The labor limit has been increased to 150MPa from 100MPa, promotes 50%.Preset abnormality twin can effectively improve its fatigue behaviour.

Embodiment 3

The present embodiment is Mg-2Y magnesium alloy hot rolled plates using raw material, after 450 DEG C of homogenizing annealing 2h, average crystalline substance Particle size is about 120 μm.Pre- alternating bending processing is carried out to it at 150 DEG C.Due to the particularity of alternating bending mode of texturing, in Property layer both sides group be woven in during alternating bending can be successively by the load of two opposite directions.Suitable bending side should be chosen Formula ensures that its crystal grain basal plane and loading direction are in 15~60 °, and accumulative dependent variable is about 0.002~0.04.

Analysis is carried out to tissue orientating's distribution map 5 (a) after pre-treatment and by (0001) base containing twin crystal grain Face pole figure Fig. 5 (b) makes and divides region, and 5 is during alternating bending, (hang down in Fig. 5 (b) when stretching or compress along the directions LD Straight paper direction), corresponding normal twin area, 6 are unusual twin areas.These crystal grain it can be seen from Fig. 5 (b) (0001) angle of basal plane normal direction and loading direction is concentrated mainly at 15~60 °, meets 15~75 ° of unusual twin criterions, nothing By being to stretch or compress, the twin generated in these crystal grain is all unusual twin.

Its fatigue behaviour is tested at room temperature, gained stress amplitude-cycle-index curve comparison figure is with it in fatigue Stress-strain B-H loop comparison diagram when ultimate strength half-life is as shown in Figure 6.Compare the stress amplitude-cycle time of the two Number curve (Fig. 6 (a)) it is found that preset abnormality twin Mg-2Y alloy test specimens, the cycle-index under same stress amplitude is greater than Not preset unusual twin test specimen, the fatigue limit of test specimen have also been increased to 50MPa from 30MPa, have promoted 67%.Meanwhile it is preset anti- Stress-strain B-H loop relative narrower when half-life after normal twin, the area surrounded are relatively small (Fig. 6 (b)).This meaning Taste in cyclic process that consumed strain energy is small, and fatigue damage is smaller.Preset abnormality twin can effectively improve its fatigue behaviour.

Claims (4)

1. a kind of method improving magnesium-rare earth fatigue behaviour using unusual twin, it is characterised in that:In 15~300 DEG C of lower edges Basal plane easy glide direction carries out pre-treatment, deflection in 15~80 ° of direction along with basal plane normal direction to magnesium-rare earth It is determined by the yield point of the alloy, true strain is 0.0005~0.1, preset into magnesium-rare earth { 10-12 } by predeformation Unusual twin inhibits the friendship of magnesium-rare earth fatigue process Dislocations to slide using the pinning effect of unusual twin On Dislocation Motion It moves, to improve fatigue limit intensity, extend fatigue life, improves fatigue behaviour;The unusual twin is relatively normal For { 10-12 } twin, normal twin, which refers to, geometrically to be thought with crystal grain basal plane normal direction in 0 ° of stretching or when being compressed in 90 ° with it { 10-12 } twin generated;And along when magnesium-rare earth being stretched or compressed in 15~75 ° of direction with basal plane normal direction, { 10-12 } twin occurred is then { 10-12 } unusual twin;The magnesium-rare earth is Mg-1.5Gd, Mg-6Gd-3Y- 1Zn-0.4Zr or Mg-2Y.
2. a kind of method improving magnesium-rare earth fatigue behaviour using unusual twin according to claim 1, feature It is:The pre-treatment is using one or more processing modes in pre-stretching, compression, bending.
3. a kind of method improving magnesium-rare earth fatigue behaviour using unusual twin according to claim 1, feature It is:25~300 DEG C of the predeformation temperature range, 0.001~0.3s of predeformation speed range-1, predeformation amount is by the alloy Yield point determine, true strain be 0.002~0.05.
4. a kind of method improving magnesium-rare earth fatigue behaviour using unusual twin according to claim 1, feature It is:The loading direction of the predeformation should be in 15~60 ° of side along the direction of basal plane easy glide, in particular to basal plane normal direction To.
CN201710366055.8A 2017-05-22 2017-05-22 A method of improving magnesium-rare earth fatigue behaviour using unusual twin CN107190220B (en)

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KR0149219B1 (en) * 1994-12-27 1998-12-01 김주용 Charge pump circuit
CN101463454B (en) * 2009-01-16 2010-06-16 中南大学 Method for preparing bulk nano/superfine crystal grain magnesium alloy by twinning deformation
KR101139879B1 (en) * 2009-07-17 2012-05-02 포항공과대학교 산학협력단 Method for manufacturing wrought magnesium alloy having improved low-cycle fatigue life using pre-straining
KR101324715B1 (en) * 2012-02-13 2013-11-05 한국기계연구원 A method for increasing formability of magnesium alloy sheet and magnesium alloy sheet prepared by the same method
JP6587174B2 (en) * 2015-04-28 2019-10-09 国立研究開発法人物質・材料研究機構 High toughness magnesium-based alloy extender and method for producing the same
CN105112827B (en) * 2015-09-14 2017-01-25 重庆大学 Method for refining crystalline grains of wrought magnesium alloy at room temperature
CN105463354A (en) * 2016-01-22 2016-04-06 重庆大学 Method for improving strength of magnesium alloy plate through pre-stretching and low-temperature annealing technology

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