CN103924097A

CN103924097A - Ultrasonic/inert gas combined degassing technology

Info

Publication number: CN103924097A
Application number: CN201310524453.XA
Authority: CN
Inventors: 李晓谦; 蒋日鹏; 张立华; 郭东柱
Original assignee: Central South University
Current assignee: Central South University
Priority date: 2013-10-31
Filing date: 2013-10-31
Publication date: 2014-07-16

Abstract

The invention discloses an ultrasonic/inert gas combined degassing technology which is a comprehensive technology integrating an ultrasonic degassing technology, an inert gas degassing technology and metal solidification technology in one, and is a combined degassing method which can achieve high hydrogen removal efficiency and low hydrogen content, and can meet the casting requirements of high-purity large-size aluminum alloy ingots.

Description

Ultrasonic/rare gas element associating outgas technique

Technical field

Ultrasonic applications technology, metal sublimate technology.

Background technology

The high-tech sectors such as modern space flight and aviation, traffic delivery, information industry, particularly the important hi-tech of national Important Project planning is equipped, not only aluminium alloy capability has been proposed to more and more high requirement, and require to adopt large-scale integral member to alleviate structural weight, improve rigidity and the validity of equipment.Along with different field improves day by day to aluminium performance requriements, the preparation of high-performance aluminium is the pressing issues that aluminium industry sustainable development faces.High strength alumin ium alloy over-all properties is low, and large specification aluminium ingot casting can not be produced in qualified preparation, causes high-performance aluminium critical shortage.Wherein pore is one of main defect in aluminium alloy cast ingot, and its generation can reduce physical strength and the mechanical property of material greatly.Pore is to produce because gas dissolves wherein in the process of setting of aluminium alloy melt, and hydrogen is the main gas that can slightly be dissolved in aluminium alloy.Therefore control the content of Hydrogen In Molten Aluminum Alloys for producing pore-free and most important without the high-performance aluminium alloy of shrinkage cavity.For the high-strength high-performance Al-alloy products of aerospace industry application, the index of hydrogen richness is particularly important, requires every 100g aluminium alloy hydrogen content to be no more than 0.1mL.Outgas technique is mainly to utilize the online outgas technique of partial pressure difference degasification at present.In addition, ultrasonic degassing technology is paid attention to by people as a kind of new and effective technology.

In order further to improve the action effect to aluminium alloy ultrasonic cleaning degasification, the present invention gets up ultrasonic outgas technique and inert gas deaeration technical tie-up.

Summary of the invention

Problem to be solved by this invention is that ultrasonic outgas technique and inertia outgas technique are effectively joined together, obtain more high-efficiency degasification efficiency and the hydrogen richness of aluminium alloy melt is even lower, for the large size ingot-casting castingprocesses of high-performance provides a kind of more outstanding outgas technique.

As shown in Figure 1, rare gas element passes into melt from melt bottom by the device of logical rare gas element single inert gas deaeration technology, and inertia bubble floats in melt subsequently, reaches the object of degasification in floating-upward process.

Ultrasonic outgas technique schematic diagram as shown in Figure 2, ultrasonicly imports to aluminium alloy melt from the top of melt by ultrasound emission end.Under ultrasonic effect, " thin spot " in melt forms cavitation nucleus, and cavitation nucleus forms cavitation bubble under the acoustic pressure effect alternately changing.Hydrogen in melt due to the diffusion mass transfer of ultrasonic cavitation, three aspects of pressure and temperature gradient mass transfer of the effect layer of ultrasonic cavitation bubble and surface effects, the collapse of ultrasonic cavitation bubble can enter into cavitation bubble, but due to the small and collapsibility of cavitation bubble, thereby only have small portion cavitation bubble in melt, to be gathered into larger bubble at self buoyancy float downward discharge bath surface.Most of cavitation bubble can collapse, and forms new cavitation nucleon, reenters next step cavitation and expands and compression, and this has just affected ultrasonic degassing efficiency to a certain extent.

So-called " ultrasonic/rare gas element associating degasification " is that two kinds of outgas technique are above joined together to use, and at aluminium alloy melt top, applies ultrasonic vibration, the logical inertia bubble in bottom, as shown in Figure 3.Inertia bubble always itself has certain dehydrogenation effect at floating-upward process, when inertia bubble floats to ultrasonic cavitation region, and the indifferent gas generation steady-static vibration of steeping oneself-meeting, in vibration, small cavitation bubble can be added in inertia bubble, thereby reduces the quantity of the cavitation bubble of collapse, as shown in Figure 4.Due to inertia bubble and ultrasonic coordinative role, ultrasonic degassing efficiency is accelerated, degassing effect is better, and after degasification, hydrogen richness is lower.

Advantage of the present invention is: the mode of the ultrasonic and rare gas element associating degasification of the employing of novelty, hydrogen richness after further improving speed and the efficiency of ultrasonic degasification and reducing degasification, be applicable to semicontinuous casting and the continuous casting of large-size aluminum alloy ingot, there is wide popularization and application and be worth.

Accompanying drawing explanation

Fig. 1 is inert gas deaeration schematic diagram.

Fig. 2 is ultrasonic degasification schematic diagram.

Fig. 3 is ultrasonic/rare gas element associating degasification schematic diagram.

Fig. 4 is ultrasonic/rare gas element associating degasification principle analysis schematic diagram.

Fig. 5 is the hydrogen richness temporal evolution curve of rare gas element, ultrasonic and the two associating degasification.

Fig. 6 is rare gas element, ultrasonic and the two associating degassing efficiency temporal evolution curve.

Embodiment

Below in conjunction with the drawings and specific embodiments, the invention will be further described.

Experiment schematic diagram as shown in Figure 1, 2, 3, has carried out relevant inert gas deaeration experiment, ultrasonic degasification experiment and the two associating degasification experiment.The equipment that three experiments are selected comprises altogether: independent-excited ultrasonic generator; Piezoelectric ceramic type transverter, design frequency is 20KHz; 45# steel horn and titanium alloy transmitting terminal; Rare gas element breather.Other utility appliance: Resistant heating stove; Plumbago crucible; Displacement operation platform; ALSCAN hydrogen meter.

Inert gas deaeration experimental procedure is as Fig. 1: 7050 aluminium alloys are put into plumbago crucible, then put into resistance furnace and be heated to 800 ℃, treat that aluminium alloy melts completely, add slagging agent to remove the gred and be incubated 800 ℃ of for some time.Then melt temperature is maintained between 710～720 ℃.First use ALSCAN to measure the initial hydrogen content of molten aluminium.Then pass into the nitrogen of 15kpa, produce the nitrogen bubble of 1mm left and right, the breather that swings back and forth in venting process, guarantees that gas can arrive crucible every nook and cranny.Aeration time is 160s, and then uses hydrogen meter to measure hydrogen richness.And then the 160s measure hydrogen richness of ventilating, continue to repeat 4 times and also record measured hydrogen richness data.

Ultrasonic degasification experimental procedure is as Fig. 2: equivalent 7050 aluminium alloys are put into plumbago crucible, equally with front step heat and be incubated, then ultrasonic emitting end is inserted to the melt 20mm degree of depth, treat that temperature-stable is between 710～720 ℃, measure its initial hydrogen content.Then open ultrasonic 3 grades of power supplys and apply ultrasonic vibration, execute the time of shaking and get 180s, then measure Dissolved H in Liquid Al-Si Alloy content.And then execute respectively the 120s that shakes, 180s, 120s and record measured hydrogen richness data.

Associating degasification experimental procedure is as shown in Figure 3: 7050 aluminium alloys are put into plumbago crucible, equally with front step heat and be incubated.Then ultrasonic emitting end is inserted to the melt 20mm degree of depth, treat that temperature-stable is between 710～720 ℃, measure initial hydrogen content.Then ultrasonic power is transferred to 3 grades aluminium alloy melt is applied to ultrasonic wave, pass into the nitrogen of 15kpa simultaneously, the breather that swings back and forth, keeps ultrasonic and aeration time 180s, then closes ultrasonic and stops ventilation, re-uses hydrogen meter and measures hydrogen richness.Measurement completes the follow-up continuous ultrasonic and ventilation that applies, and is respectively 120s action time, and hydrogen richness measured in 180s and 120s respectively record.

Conclusion (of pressure testing): three kinds of degassing efficiency contrasts as shown in Figure 5,6, ultrasonic and rare gas element associating degassing efficiency can reach 80%, minimum hydrogen richness can drop to 0.07ml/100gAL, and ultrasonic or rare gas element is when used separately, and its effect and the minimum hydrogen richness that can reach are all not so good as associating degasification.

Claims

1. ultrasonic/rare gas element associating outgas technique, is characterized in that: ultrasonic and rare gas element associating degasification.