The preparation method of the grain-refining agent of Mg-Al series magnesium alloy
Technical field
The present invention relates to a kind of preparation method of grain-refining agent of the Mg-Al of being used for series magnesium alloy, utilize the grain-refining agent of preparation can make magnesium alloy grains, and its intensity and toughness are significantly improved.Belong to the metallic substance technical field.
Background technology
Magnesium alloy is a structural metallic materials the lightest in the practical application, and it has light specific gravity, specific tenacity and specific rigidity height, advantages such as damping capacity, machinability, good casting property.But the intensity of magnesium alloy and toughness are lower, at Hall-patch (σ=σ
0+ Kd
-1/2) in the formula, the size and the Taylor of K value are factor-related, and how much being inversely proportional to of the slip system in the Taylor factor and the alloy.Therefore, the Taylor factor of close-packed hexagonal is greater than face-centered cubic and body-centred cubic metal, and makes grain size bigger to the influence of close-packed hexagonal metal.Thus, the compact grained magnesium alloy materials has higher intensity.Simultaneously, grain refining also can improve the toughness of magnesium alloy materials.
Up to now, it is a variety of that Mg-Al is that the crystal fining method of alloy has had, and for example: overheated method, Elfinal method (add FeCl
3), the rotten method of carbon, stirring means, interpolation particulate (Al
4C
3, AIN, SiC, TiC, CaC
2) and solute atoms (Sr, B, Ce, Nd, Y, La, C) etc.In the middle of these methods, the most practical with the rotten method of carbon, because it has low deterroration and thinning effect preferably, (Grain refiningmechanism of a carbon addition method in a Mg-Al magnesium alloy, ScriptaMaterialia 2003; 49:pp1129-1132.) but the rotten method of carbon is normally added C in magnesium alloy
2Cl
6Perhaps CCl
4Deng the compound that contains carbon atom, and these compounds can be emitted a large amount of chlorine in the process on the turn, environment and human body are produced great harm, and the paracme of this method is shorter, generally about 20~30 minutes, therefore in industrial application, usually to carry out secondary metamorphic, so not only aggravate pollution, and can make the downgrade of magnesium alloy environment.
Summary of the invention
The objective of the invention is at the deficiencies in the prior art, a kind of preparation method of grain-refining agent of Mg-Al series magnesium alloy is proposed, method is simple, can not pollute environment, the magnesium alloy grains agent that utilizes lower production cost to prepare can effectively improve the mechanical property and the quality of magnesium alloy.
It is specific as follows that the present invention prepares the method for Mg-Al series magnesium alloy grain-refining agent:
After adopting electromagnetic induction furnace with the fine aluminium fusing, be warming up to 780~820 ℃, sprinkle the insulating covering agent of layer of aluminum alloy on aluminium liquid surface, the thickness of insulating covering agent is at 0.8~1.2cm, treat the insulating covering agent fusing after, add K
2TiF
6And KBF
4The mixture of two kinds of salt is incubated 20~30 minutes then, and temperature is risen to 1000~1200 ℃, the salt deposit on aluminium liquid surface is clawed, cool the temperature to 780~820 ℃ again, slagging-off, stir after adding pure Sr, be cast into intermediate alloy ingot after the degasification, promptly obtain Mg-Al series magnesium alloy grain-refining agent.Wherein, K
2TiF
6Add-on be 20~40% of aluminium liquid weight, KBF
4Add-on be 20~60% of aluminium liquid weight, the add-on of pure Sr is 1~2% of an aluminium liquid weight.
Utilize the grain-refining agent of a kind of Mg-Al of being used for series magnesium alloy that the inventive method obtains, the weight percent of its each component (wt.%) is: aluminium (Al) 90.00~95.00%, titanium (Ti) 3.00~5.00%, boron (B) 1.00~5.00%, strontium (Sr) 0.5~1.0%.
The grain-refining agent of the present invention's preparation is in the application process of Mg-Al series magnesium alloy refinement, and the addition of fining agent is 0.1~1.0wt%, and adding temperature is 720~800 ℃.
Method of the present invention is simple, and production cost is low, and the fining agent of preparation is to the good in refining effect of Mg-Al series magnesium alloy, and significantly the Mg-Al series magnesium alloy is out of shape in refinement, and its intensity and toughness are significantly improved.
Embodiment
Below by specific embodiment technical scheme of the present invention is described in detail.
Embodiment 1
The preparation of fining agent:
After adopting electromagnetic induction furnace with the fine aluminium fusing, be warming up to 780 ℃, sprinkle the insulating covering agent of layer of aluminum alloy on aluminium liquid surface, be approximately a cm thick, treat the insulating covering agent fusing after, be incorporated as the K of aluminium liquid weight 40%
2TiF
6With 20% KBF
4The mixture of two kinds of salt is incubated 20 minutes then, and temperature is risen to 1000 ℃, after the salt deposit on aluminium liquid surface is clawed, cools the temperature to 780 ℃, and slagging-off stirs after being incorporated as the pure Sr of aluminium liquid weight 2%, is cast into intermediate alloy ingot after the degasification.
Process for refining:
At CO
2+ SF
6Add industrial AZ31 magnesium alloy ingot 3000g in the gas shield electrical crucible, treat alloy melting after, add the fining agent of 1.0wt%, alloy liquid is fully stirred in the dissolving back, after 730 ℃ of insulations are left standstill 20 minutes, is molded in the metal type dies.Sample line is cut into the tension specimen of standard.The result of grain-size and tensile property is as follows:
| Grain-size (μ m) | Tensile strength (MPa) | Yield strength (MPa) | Unit elongation (%) |
Do not add fining agent and add fining agent | 1100~1300 150~200 | 160~180 170~190 | 41~45 45~48 | 8~10 11~13 |
Embodiment 2
The preparation of fining agent:
After adopting electromagnetic induction furnace with the fine aluminium fusing, be warming up to 800 ℃, sprinkle the insulating covering agent of layer of aluminum alloy on aluminium liquid surface, be approximately 0.8 cm thick, treat the insulating covering agent fusing after, be incorporated as the K of aluminium liquid weight 20%
2TiF
6With 40% KBF
4The mixture of two kinds of salt is incubated 25 minutes then, and temperature is risen to 1100 ℃, after the salt deposit on aluminium liquid surface is clawed, cools the temperature to 800 ℃ again, and slagging-off stirs after being incorporated as the pure Sr of aluminium liquid weight 1.5%, is cast into intermediate alloy ingot after the degasification.
Process for refining:
At CO
2+ SF
6Add industrial AZ31 magnesium alloy ingot 3000g in the gas shield electrical crucible, treat alloy melting after, add the master alloy of 0.5wt%, alloy liquid is fully stirred in the dissolving back, after 730 ℃ of insulations are left standstill 20 minutes, is molded in the metal type dies.Sample line is cut into the tension specimen of standard.The result of grain-size and tensile property is as follows:
| Grain-size (μ m) | Tensile strength (MPa) | Yield strength (MPa) | Unit elongation (%) |
Do not add fining agent and add fining agent | 1100~1300 100~150 | 160~180 180~200 | 41~45 50~55 | 8~10 13~15 |
Embodiment 3
The preparation of fining agent:
After adopting electromagnetic induction furnace with the fine aluminium fusing, be warming up to 820 ℃, sprinkle the insulating covering agent of layer of aluminum alloy on aluminium liquid surface, be approximately 1.2 cm thicks, treat the insulating covering agent fusing after, be incorporated as the K of aluminium liquid weight 30%
2TiF
6With 60% KBF
4The mixture of two kinds of salt is incubated 30 minutes then, and temperature is risen to 1200 ℃, after the salt deposit on aluminium liquid surface is clawed, cools the temperature to 820 ℃ again, and slagging-off stirs after being incorporated as the pure Sr of aluminium liquid weight 1%, is cast into intermediate alloy ingot after the degasification.
Process for refining:
At CO
2+ SF
6Add industrial AZ31 magnesium alloy ingot 3000g in the gas shield electrical crucible, treat alloy melting after, add the master alloy of 0.25wt%, alloy liquid is fully stirred in the dissolving back, after 730 ℃ of insulations are left standstill 20 minutes, is molded in the metal type dies.Sample line is cut into the tension specimen of standard.The result of grain-size and tensile property is as follows:
| Grain-size (μ m) | Tensile strength (MPa) | Yield strength (MPa) | Unit elongation (%) |
Do not add fining agent and add fining agent | 1100~1300 80~100 | 160~180 190~210 | 41~45 54~58 | 8~10 15~17 |