How to determine the quality of mold steel?

To judge the quality of mold steel, we need to comprehensively consider the appearance, hardness, composition, and metallographic structure:

Observation of appearance quality: The surface of high-quality mold steel should be smooth and flat, without defects such as cracks, folds, inclusions, pores, or obvious scratches. The surface color is uniform, with a metallic luster, and no rough surface or scar phenomenon. ‌

Check dimensional accuracy: Measure the size of the mold steel to ensure it meets the standard tolerance range. Small size deviation and regular shape (such as a standard circular or square cross-section) indicate good quality, while size deviation may indicate uneven material or poor production process. ‌

Testing physical properties: Evaluate the hardness, toughness, strength, and wear resistance of mold steel through hardness testing (such as using a hardness tester), impact testing, and tensile testing. Moderate and uniform hardness, as well as good toughness (not easily broken), are the characteristics of high-quality mold steel. ‌

Analyze chemical composition: The performance of mold steel depends on its chemical composition (such as the content of elements such as carbon, chromium, molybdenum, etc.). By conducting professional testing or requesting a composition report, it is ensured that it meets relevant standards. For example, high carbon steel usually has high hardness but low toughness, and the content of alloying elements affects corrosion resistance and thermal strength. ‌

Perform non-destructive testing: Use techniques such as ultrasonic testing or radiographic testing to inspect for internal defects such as cracks, pores, segregation, or delamination, which may affect the service life and reliability of the mold. ‌

Through metallographic analysis: observe whether the microstructure is uniform, and whether the grains of high-quality mold steel are small and evenly distributed. If the organization is coarse or uneven, it indicates that there may be a problem with the material quality.

Evaluate production processes and sources: Understand the manufacturer's reputation and production processes. Mold steel produced by legitimate manufacturers usually has more stable quality and should provide factory certificates, quality assurance certificates, and other documents. ‌

Pay attention to corrosion resistance and heat treatment performance: For specific applications (such as plastic molds), corrosion resistance testing (such as salt spray testing) is important; Hot work mold steel also needs to be checked for its performance stability at high temperatures. ‌