| Magnesium alloy materials have been recognized by the public as an emerging metal structural material due to their low density and high strength.However,many problems with magnesium alloys have not been solved and they have not been widely used.Among them,the influence of refinement and purification on the performance of various aspects of the alloy has attracted great attention from scholars in recent years.In this paper,the effects of ultrasonic field and argon on the solidification structure of alloy ingot,hydrogen content in the melt,mechanical properties at room temperature,corrosion resistance and thermal compression properties were investigated,which provided a method for obtaining high quality magnesium alloy ingot preparation technology.reference.After the ultrasonic power is 2000W,the hydrogen content of Mg-3Ca alloy can be reduced to 57cm3/100g when treated for Os,30s,60s,90s and 120s.At this time,the outgassing rate is 32.1%,continue to increase the application.The time is up to 120s,the hydrogen content is 69 cm3/100g,and the hydrogen content is increased.With the further progress of the ultrasonic treatment,the hydrogen content in the Mg-6Ca alloy gradually decreased.After 120s of sonication,the hydrogen content in the alloy was reduced to 70cm3/100g,and the maximum outgassing rate was also reached at 16.7%.The Mg-9Ca alloy is similar to Mg-6Ca.When the ultrasonic treatment time is 120s,the hydrogen content of the ingot is the lowest,65.5cm3/100g,and the degassing rate reaches a maximum of 32.5%.Since the hydrogen content is intimately related to the elemental species of the alloy,the maximum outgassing rate of each alloy will vary,and this difference is affected by the type of added elements in the alloy.The maximum outgassing rates of Mg-3Ca,Mg-3Zn and Mg-3Al alloys were 32.1%,36%and 40.4%,respectively.The hydrogen content in the magnesium alloy is also affected by the content of the alloying elements,and the more the alloying element content,the larger the hydrogen content.The soot content of the ingot decreased after sonication.The AZ91 magnesium alloy has the highest hydrogen content when it is not ultrasonically treated,reaching 19.4cm3/100g.After 150W ultrasonic treatment for 90s,the hydrogen content in the magnesium alloy melt is reduced to 9.6cm3/100g,and the outgassing rate is as high as 50.5%.After degassing treatment,the elongation increased from 2.8%to 4.8%;the tensile strength increased from 152 MPa to 194 MPa;the yield strength increased from 125 MPa to 133 MPa;and the hardness increased from 30.7 to 67.8.It shows that the hydrogen content has a great influence on the properties of the alloy.Degassing treatment can significantly reduce the average corrosion rate of the billet for magnesium alloys,but for alloys the corrosion potential(Ecorr)has little effect According to the results of the full immersion corrosion test,the average corrosion rate of the untreated AZ91 magnesium alloy was 7738mg/m2·h,and the average corrosion rate of the degassed AZ91 magnesium alloy was 4684.3mg/m2·h,which was reduced by 39.5%;the corrosion current density ratio after degassing is smaller than that of the degassed billet,and the average value can be reduced from 44.277 ?tA/cm 2 to 32.467?A/cm 2 with a reduction of 26.7%.When the alloy were thermal compression tested at 250??400?C and at strain rates of 0.01s-1?10s-1,the flow stress decreased with increasing temperature,and increased with increasing the strain rate.The flow stress of degassing in ingot is higher than that of without degassing.The constitutive equation in sample having without degassing sample is:?=1.19855×1014[sinh(0.00836?)]7.52635 exp[-175.1158×103/(RT)]The constitutive equation in sample having degassing sample is:?=6.35746×1012[sinh(0.00976?)]6.05515 exp[-165.2974×103/(RT)]... |
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