Chinese standard GB/T388-92 die-cast zinc alloy
China’s national standard GB/T388-92 is a key national standard for die-cast zinc alloys. It provides clear technical specifications for the production, inspection, and application of die-cast zinc alloys. This standard is crucial for ensuring the quality of die-cast zinc alloy products and promoting the healthy development of the industry. Since its implementation, this standard has played a positive role in regulating market order and improving product competitiveness.
GB/T388-92 provides detailed regulations regarding alloy grades and chemical composition. The standard classifies die-cast zinc alloys into multiple grades, such as ZA9-4 and ZA10-5, each corresponding to a specific chemical composition range. Taking ZA9-4 as an example, the standard specifies the primary zinc content, as well as the specific content ranges for alloying elements such as aluminum, copper, and magnesium. The addition of aluminum can increase the strength and hardness of zinc alloys and improve their casting properties; copper can further enhance the alloy’s strength and wear resistance, but excessive levels can increase the alloy’s brittleness; and magnesium helps improve the zinc alloy’s corrosion resistance and grain refinement. Furthermore, the standard strictly limits the content of harmful impurities such as lead, cadmium, and iron to prevent these impurities from adversely affecting the physical and mechanical properties of zinc alloys, thereby ensuring the quality stability of die-cast zinc alloys.
Mechanical property requirements are a core component of GB/T388-92. The standard specifies mechanical properties such as tensile strength, elongation, and hardness for different grades of die-cast zinc alloys. For example, for ZA10-5 die-cast zinc alloy, its tensile strength should be no less than 245 MPa, its elongation no less than 3%, and its Brinell hardness no less than 80 HB. These specifications are based on extensive test data and practical application experience and are designed to meet the requirements of die-cast zinc alloys across various industries. In the automotive industry, die-cast zinc alloys used in engine mounts, transmission components, and other applications require high tensile strength and hardness. Components requiring flexibility, such as toy joints and instrument connectors, have even higher elongation requirements. Clearly defined mechanical property indicators enable manufacturers to tailor their production processes to ensure their products meet standard requirements.
Standardization of test methods is a key element of GB/T388-92’s product quality assurance. The standard details the specific methods and operating procedures for chemical composition analysis and mechanical properties testing. For chemical composition analysis, proven and reliable methods such as chemical analysis and spectral analysis are recommended. Clear instructions are provided for sample collection, preparation, and analysis procedures to ensure the accuracy and consistency of the analysis results. For mechanical properties testing, strict regulations apply to the shape and dimensions of specimens for tensile and hardness tests, the precision requirements for test equipment, and test environment conditions. For example, tensile test specimens must meet the dimensional accuracy specified in the standard, and the test speed must be controlled within a certain range to ensure the reliability of the test data. These standardized test methods provide comparable test results for different companies and inspection agencies, facilitating the assessment and supervision of product quality.
Inspection rules and quality assurance are crucial components of product quality assurance in GB/T388-92. The standard specifies the items, frequency, and criteria for factory inspection and type testing of die-cast zinc alloys. Factory inspection is a routine test conducted on each batch of products, primarily including spot checks of chemical composition and mechanical properties to ensure product quality meets standard requirements. Type testing is a comprehensive inspection conducted upon product finalization, or when significant changes are made to raw materials or production processes. It covers all technical specifications specified in the standard. Furthermore, the standard requires manufacturers to establish a comprehensive quality assurance system, strictly control every step of the production process, maintain quality records, and ensure traceability of product quality. For products that fail inspection, the standard specifies appropriate procedures, such as rework, downgrading, or scrapping, to maintain the rigor of the standard and market order. Strict implementation of these inspection rules and quality assurance measures can effectively improve the overall quality of die-cast zinc alloys and promote the standardized development of the industry.
