Effect Of Solidification Conditions Of Low Pressure Casting On Microstruction And Mechanical Properties Of ZL205A Alloy Castings

This paper employs the low pressure die-casting method to prepare ZL205 A alloy barrel-shapes sample. And as the research object study the effects of the pressure, wall thickness, location on the microstructure and the mechanical properties of ZL205 A cylinders.The effects of solidification conditions on the microstructure have been investigated. For the as-cast sample, along with the increase of the pressure, the average size of grain decreases slightly, the microstructure is more and more dense, the level of shrinkage decreased obviously; along with the increase of the wall thickness, the average grain size of ZL205 A alloy increase, shrinkage level as well, when the change from 15 mm to 25 mm, the average grain size of away from the gate increases from 68 um to 128 um. When the wall thickness of 45 mm, the average size of away from the gate is95 um, near the gate respectively is 132,127 um. The shrinkage of away from the gate is low, when the wall thickness is small, the influence of location is small. After T6 heat treatment, the microstructure is slightly bulky compare with as-cast, the level of shrinkage did not change obviously.The effects of solidification conditions on the ZL205 A alloy density have been investigated. When the wall thickness is 5 or 45 mm, along with the holding pressure increasing the the effect on density is not obvious; when the wall thickness is 15 or25 mm, with the increase of the holding pressure, the rising trend of density is obvious.With the increase of the wall thickness, ZL205 A alloy’s density first increases then decreases, the maximum density when the wall thickness is 15mm; the density sharply decline from 15 mm to 25 mm when the holding pressure is 65 kPa. From A to C of the casting position the density rise when the holding pressure is high.The effects of solidification conditions on the mechanical properties have been investigated. With the increasing of the holding pressure, the mechanical properties have been improved effectly. When the wall thickness is 45 mm, the tensile strength is improved greatly from 65 kPa to 75 kPa and the change of elongation with holding pressure is not obvious. With the increase of the wall thickness, ZL205 A alloy’s tensile strength first increases then decreases, the maximum density when the wall thickness is15 mm, as well the elongation. When the wall thickness change from 15 mm to 25 mm,the elongation is decline, similar to the density changes. The casting position is not significant influence on the mechanical prooerties and the regularity is not obvious.Alloy and the average grain size affect mechanical propersity together. When the average grain size is similar, the density has significant effects on mechnical properties.The effect of density on elongation is very obvious.