Comparative Analysis of Aluminum Alloy Die - Castings Before and After Brazing
May. 31, 2025
Aluminum alloy die - castings are widely used in numerous fields due to their advantages of light weight, high strength, good corrosion resistance, and ease of forming. Brazing, as an important joining process, can effectively connect multiple aluminum alloy die - castings or die - castings with other metal components to form an integrated structure with specific functions. The following will provide a detailed analysis of the key performance and state changes of aluminum alloy die - castings before and after brazing in the form of a comparative table:
Comparison Items | Before Brazing | After Brazing |
Appearance |
The surface is smooth, showing the unique texture and shape of the die - cast part, with clear edges and no obvious signs of connection or deformation. Each component exists independently, with a complete but separate structure | At the joint area after brazing, there are traces of filler metal filling. The surface may change slightly due to the high temperature and chemical reactions during the brazing process, such as showing a slight oxidation tint or the luster of the filler metal. Multiple die - cast parts are tightly connected into a whole through the filler metal, resulting in a more complex yet coherent structure |
Dimensional Accuracy | It has high dimensional accuracy, meeting the design requirements of the die - casting mold, with a relatively small tolerance range. The relative positional relationships between various components are accurate, enabling them to meet assembly requirements | Due to thermal expansion and cooling contraction during the brazing process, certain dimensional changes may occur. However, through reasonable process control, the dimensional changes can be kept within the allowable tolerance range. Nevertheless, the dimensional accuracy of the overall structure may be somewhat affected, especially the dimensional accuracy at the connection sites |
Mechanical properties | Strength: It has a certain degree of strength and can withstand a certain amount of external force. However, the strength mainly depends on the material and structure of the die-casting part itself. Toughness: It has good toughness and can resist impact and deformation to a certain extent. Fatigue performance: Under alternating load, it has a certain fatigue life, but it is relatively low. | Strength: The strength of the joint area depends on the bonding strength between the brazing filler metal and the aluminum alloy matrix. If the brazing process is carried out properly, the strength of the joint area can approach, reach, or even exceed that of the die - casting part itself, thereby enhancing the load - bearing capacity of the entire structure. Toughness: The toughness after brazing will be affected to some extent because the addition of the brazing filler metal may alter the local material structure. However, by selecting appropriate brazing filler metals and process parameters, relatively good toughness can be maintained to a certain degree. Fatigue performance: The fatigue performance is usually improved because brazed joints can eliminate the gaps between die - casting parts and reduce stress concentration, thus increasing the service life of the entire structure under alternating loads.
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Sealing performance |
Independent aluminum alloy die - castings do not possess sealing performance on their own, unless sealed through additional sealing measures (such as rubber sealing rings). | After brazing, a good seal can be formed at the joint area. The brazing filler metal fills the gaps between the die - castings, effectively preventing the leakage of media like gases and liquids, and meeting the requirements of application scenarios with high sealing demands, such as the cooling systems of automobile engines and the fuel systems of aerospace equipment. |
Corrosion resistance |
The surface of aluminum alloy die - casting parts usually undergoes certain surface treatments (such as anodizing) to enhance their corrosion resistance. In normal use environments, they can resist corrosion to a certain extent | During the brazing process, the high temperature may partially damage the oxide film on the surface of aluminum alloy die - casting parts, thereby affecting their corrosion resistance. However, the selection of brazing filler metals and subsequent surface treatment processes can compensate for this impact. |
Electrical conductivity | Aluminum alloy itself has good electrical conductivity. The electrical conductivity of die - casting parts mainly depends on the composition and purity of the aluminum alloy. | The addition of the brazing filler metal may have a certain impact on the electrical conductivity of the joint area. Brazing filler metals with different compositions have different electrical conductivities. If the electrical conductivity of the brazing filler metal is lower than that of the aluminum alloy, the resistance of the joint area may increase. However, in some applications where the requirement for electrical conductivity is not particularly high, this impact may be negligible. For applications with high demands on electrical conductivity, brazing filler metals with better electrical conductivity can be selected. |
From the above comparison, it is evident that aluminum alloy die - casting parts undergo significant changes in multiple aspects before and after brazing. Although the brazing process may bring about some adverse effects, by giving full play to its advantages, comprehensively considering the performance variations before and after brazing, and selecting appropriate brazing processes and materials, we can ensure that the quality and performance of aluminum alloy die - casting parts after brazing meet the usage requirements.
