Analysis of the Casting Process of New Die-Casting Parts for Automobiles

In today’s rapid economic development, people’s life and travel are more and more inseparable from the car. The quality of the car, performance, economy, service life, etc., have higher requirements. At the same time, based on energy saving and emission reduction, consumption reduction, lightweight, and another new development concept, automotive materials tend to be more lightweight, high performance, and environmental protection; aluminum, magnesium alloy, and other lightweight metals have been more research and application [1]. And a wide variety of automotive parts, complex shapes, such as cylinder blocks, transmission, cylinder head, wheel hub, etc., mostly large, complex thin-walled parts, and therefore in the production process, gradually turn to die-casting, automotive die-casting parts by the industry more attention and application. Although the die-casting process is better than standard casting technology, the surface is smoother, the wall is thinner, precision, higher strength, simple process, high production efficiency, can greatly save raw materials, but the die-casting process is only suitable for liquid metal processing, the development is subject to certain restrictions, and die-casting also has certain casting defects, easy to produce porosity, oxidation debris, etc., and die-casting required equipment molds and other higher costs, so suitable for mass production. Although China’s die-casting technology is becoming more and more mature, greatly enhancing the quality and performance of automotive parts, based on the industry and society, the automotive die-casting parts performance of high demand, so also need to continue to develop and innovate die-casting technology, promote the development of the new type of automotive die-casting parts to a higher level.

Table of Contents

Test

The research object is Mg-9Al-1Zn-0.5Ce automotive new die-casting parts, Mg-9Al-1Zn-0.5Ce alloy of raw materials selected for the purity of The melting is carried out in a crucible resistance furnace, firstly preheat the crucible, after the crucible appears dark red sprinkle RJ-2 melt on the bottom and around the crucible, add magnesium ingot, fine manganese powder, cerium powder, aluminum ingot, zinc ingot in batches, after all the components are melted, carry out slagging and refining, let it stand for After 10min, the alloy is poured into the mold cavity of the 1250kN horizontal cold chamber die-casting machine and the die-casting test is carried out on the 1250kN horizontal cold chamber die-casting machine. During the die-casting process, the mold preheating temperature of 250°C and the injection ratio pressure of 90MPa were kept constant, and the pouring temperature and injection speed were changed. The die-casting process parameters of the specimens are shown in Table 2. all die-cast specimens are not heat treated. Figure 1 is a new type of automotive die-casting parts forging; the main dimensions are: outside diameter 88 mm, height 54 mm, thickness 5 mm, inner diameter 42 mm, and total length 101 mm.

Table 1 Chemical composition of Mg-9Al-1Zn-0.5Ce magnesium alloy (mass fraction)

Fig. 1 New die-cast parts forgings for automobiles

The mechanical properties of the new Mg-9Al-1Zn-0.5Ce automotive die-cast parts were tested at room temperature with an Instron 8032 electronic tensile tester at a constant speed of 2mm/min to record the strength and elongation after fracture and the fracture shape was observed with a The fracture shape was observed by S-530 scanning electron microscope. The corrosion resistance was tested by electrochemical corrosion method at room temperature, the test instrument was PARSTAT electrochemical three-electrode system, the corrosion medium was NaCl solution with a concentration of 3.5%, the polarization curve was tested at a speed of 0.4mV/s, and Tafel fitting was carried out in combination with analysis software, the electrochemical parameters (corrosion potential) were recorded, and S-530 SEM observed the corrosion morphology.

Test results and discussion

Mechanical properties of specimens at different pouring temperatures

The mechanical properties of Mg-9Al-1Zn-0.5Ce automotive new die-cast parts specimens prepared at a constant injection speed of 3m/s and different pouring temperatures are shown in Figure 2. The specimens’ tensile strength and yield strength at 620, 635, 650, 675, and 700°C were 237, 253, 268, 257, and 242 MPa, respectively, while the yield strength was 143, 165, 177, 169, and 154 MPa. 7.9%, 8.1%, 8.4%. It can be seen: 620 ℃ casting temperature specimen tensile strength and yield strength are the smallest, elongation after the break is the largest, the worst mechanical properties of the specimen; 650 ℃ casting temperature die-casting, the specimen of tensile strength and yield strength is the largest, respectively, compared with 620 ℃ die-casting increased by 13.08%, 23.78%, elongation after the break is only reduced by 1%, the best mechanical properties. When the pouring temperature continues to rise, the strength of the specimen decreases, the elongation after break decreases, and the mechanical properties begin to decline again.

Figure 2 Effect of pouring temperature on the mechanical properties of Mg-9Al-1Zn-0.5Ce alloy

Mechanical properties of specimens at different press injection speeds

The mechanical properties of the new Mg-9Al-1Zn-0.5Ce automotive die-cast component specimens prepared at a constant pouring temperature of 650°C and different injection speeds are shown in Figure 3.

Figure 3: Effect of injection speed on the mechanical properties of Mg-9Al-1Zn-0.5Ce alloy

As seen from Fig. 3, the slower the pressing speed, the lower the strength, and the faster the pressing speed can effectively enhance the tensile strength and yield strength of the specimens, while the elongation after fracture is slightly reduced. The elongation after the break was 8.7%, 8.4%, 7.9%, 8.2%, and 8.5%, respectively. It can be seen: 1m/s injection speed specimen tensile strength and yield strength are the smallest, elongation after the break is the largest, the worst mechanical properties of the specimen; 3m/s speed die-casting, the specimen tensile strength and yield strength is the largest, respectively, compared with 1m/s die-casting increased by 11.20%, 16.45%, elongation after the break only reduced by 0.8%, the best mechanical properties. When the die-casting speed continues to increase, the strength of the specimen decreases, the elongation after fracture decreases, and the mechanical properties begin to decline again. 2.3 Tensile fracture morphology of the specimen

Figure 4 is Mg-9Al-1Zn-0.5Ce automobile new die-casting parts specimens with 620, 650 ℃ casting temperature die-casting tensile fracture pictures. It can be seen: two casting temperature die-casting, the tensile fracture of the specimen showing typical ductile fracture characteristics. 620 ℃ die-casting specimen of the torn rib coarse, tough nest irregular, with poor toughness; 650 ℃ die-casting specimens of tough nest significantly reduced, the shape is more rounded, the distribution is more regular, uniform, toughness greatly improved, the best mechanical properties. The test results of strength and elongation of Mg-9Al-1Zn-0.5Ce automotive new die-cast parts specimens at different casting temperatures can be integrated and learned from the optimization of Mg-9Al-1Zn 0.5Ce automotive die-cast specimens; the preferred casting temperature is 650°C.

Figure 4 Tensile fracture profile of Mg-9Al-1Zn-0.5Ce alloy at different casting temperatures

Corrosion resistance of specimens at different pouring temperatures

The corrosion resistance of the new Mg-9Al-1Zn-0.5Ce automotive die-casting specimens prepared at a constant injection speed of 3m/s and different pouring temperatures are shown in Figure 6. The corrosion resistance can be improved. With the increase of casting temperature from 620℃ to 650℃, the corrosion resistance of the specimens first increased and then decreased. 620, 635, 650, 675, and 700℃ casting temperature corrosion potentials were -0.924, -0.913, -0.881, -0.893, -0.893, -0.893, and -0.893, respectively. This can be seen at 620 ℃ casting temperature, specimen corrosion potential is the most negative when the specimen corrosion resistance is the worst; at 650 ℃ casting temperature die-casting, the specimen corrosion potential is the most positive, compared with 620 ℃ die-casting is moving 43mV when the corrosion resistance is the best. When the casting temperature continued to rise, the corrosion potential of the specimen began to negative shift, corrosion resistance, and decline.

Figure 6 Effect of casting temperature on the corrosion resistance of Mg-9Al-1Zn-0.5Ce alloy

Corrosion resistance of specimens at different press injection speeds

The corrosion resistance of Mg-9Al-1Zn-0.5Ce automotive new die-cast parts specimens prepared at a constant pouring temperature of 650°C and different injection speeds are shown in Figure 7. The corrosion resistance can be improved. With the acceleration of the pressure injection speed from 1m/s to 5m/s, the corrosion potential of the specimen shifted positively and then gradually shifted negatively, and the corrosion potentials at 1, 2, 3, 4, and 5m/s pressure injection speed were -0.912, -0.906, -0.881, -0.892 and -0.892 respectively. It can be seen that 1m/s die-casting speed under the corrosion potential of the specimen is the most negative when the corrosion resistance of the specimen is the worst; at 3m/s die-casting speed, the corrosion potential of the specimen is the most positive, compared with the die-casting speed of 1m/s when the positive shift of 31mV, when the corrosion resistance is the best. When the pressure injection speed continues to increase, the corrosion potential of the specimen begins to negative shift, corrosion resistance, and decline.

Figure 7 Effect of injection speed on the corrosion resistance of Mg-9Al-1Zn-0.5Ce alloy

Corrosion morphology of specimens under different die-casting processes

Figure 8 is the corrosion profile of Mg-9Al-1Zn-0.5Ce automotive new die-casting parts specimens by 620, 650 ℃ pouring temperature die-casting pictures. Can be seen: at 620 ℃ die-casting, specimens of corrosion pits are dense group, pit depth is deeper, at this time the corrosion degree is serious; 650 ℃ die-casting specimens of corrosion degree greatly reduced, only a small amount of corrosion points appear. Contact different casting temperature Mg-9Al-1Zn-0.5Ce automotive new die-casting parts specimen corrosion potential test values can be learned from the optimization of Mg-9Al-1Zn 0.5Ce automotive die-cast specimens, a casting temperature of 650°C is preferred.

Figure 8 Surface corrosion profile of Mg-9Al-1Zn-0.5Ce alloy at different casting temperatures

Figure 9 shows the surface corrosion profile of a new Mg-9Al-1Zn-0.5Ce automotive die-cast part specimen under die-casting at 3 and 5m/s, respectively.

Figure 9 Surface corrosion profile of Mg-9Al-1Zn-0.5Ce alloy at different injection speeds

From Figure 9 can be seen: 3m / s speed injection, the specimen surface corrosion points are small, and not many, at this time, the best corrosion resistance; when the injection

speed is up to 5m/s, the corrosion of the specimen increased, there is a larger shape of corrosion pits, corrosion resistance decreased. The corrosion potential of the Mg-9Al-1Zn-0.5Ce new automotive die-cast parts specimens at different injection speeds can be linked to the corrosion potential test values to optimize the corrosion resistance of the Mg-9Al-1Zn-0.5Ce new automotive die-cast parts. 0.5Ce new automotive die-cast specimens, an injection speed of 3m/s is preferred.

Conclusion

The new Mg-9Al-1Zn-0.5Ce automotive die-cast specimens were molded using different pouring temperatures and injection speeds, and the mechanical properties and corrosion resistance were tested and analyzed. It is summarized as follows:

(1) with the rise in casting temperature and the acceleration of the injection speed, the specimen tensile strength and yield strength first increased and then decreased, with corrosion potential positive shift and then a gradual negative shift; elongation change is small, mechanical properties and corrosion resistance are first enhanced and then decreased. 650 ℃ casting temperature, 3m / s injection speed Mg-9Al 1Zn-0.5Ce automotive new die-casting parts specimens have the greatest tensile strength and yield strength, the smallest elongation after the break, the most positive corrosion potential, the best mechanical properties, and corrosion resistance.

(2) Compared with 620℃ casting temperature, the tensile strength and yield strength of 650℃ casting temperature increased by 13.08% and 23.78%, respectively, the elongation after break decreased by 1%, and the corrosion potential was positively shifted by 43mV; compared with 1m/s die casting, the tensile strength and yield strength of 3m/s die casting increased by 11.20% and 16.45% respectively. The elongation after the break was reduced by 0.8%, and the corrosion potential was positively shifted by 31mV.

(3) To optimize the mechanical properties and corrosion resistance of the new Mg-9Al-1Zn-0.5Ce automotive die-cast parts specimens, the Mg-9Al-1Zn-0.5Ce 0.5Ce automotive new die-cast parts specimen of the die-casting process parameters are preferred: 650 ℃ forging temperature, 3m / s injection speed.

Share:

Share on facebook
Facebook
Share on twitter
Twitter
Share on linkedin
LinkedIn

Related Posts

Die Casting Mold Finishing

Do you know the Effect of Cooling Water on Mold?

/*! elementor – v3.6.5 – 27-04-2022 */ .elementor-widget-image{text-align:center}.elementor-widget-image a{display:inline-block}.elementor-widget-image a img[src$=”.svg”]{width:48px}.elementor-widget-image img{vertical-align:middle;display:inline-block} Die-casting is the use of the die-casting machine will be aluminium, zinc, magnesium,

400T-Die-Casting-Machine

What is the immersion process?

In a microporous (slit) infiltration sealing process, the sealing medium (usually low-viscosity liquid) through natural infiltration (i.e., microporous self-priming) vacuum and pressure and other methods

vicky

Hi there, I'm Vicky

From V1Diecast, I’m a the marketing manager. I am familar with die casting parts and die casting technologies, including vacuum die casting, aluminium die casting, and related surface finishings. Ask for a quote for your ongoing or upcoming projects now!

Best Regards, Vicky.

Wait!

If You need any Help Please Contact Us
Email:vicky@v-1.com Phone: +86 137 9493 0097

    Place file(s) for transfer in the same folder and ZIP or RAR before attaching. If attachment over 25MB, please send via email directly.