Recently, several netizens have asked me about the differences in performance between high-toughness LG steel and 8566 chipping-resistant steel. To make it easier for everyone to understand and remember, I’ve summarized the key differences—there are roughly nine points.
1) The operating hardness differs: LG die steel has a hardness of 54–58 HRC, while 8566 chipping-resistant steel has a hardness of 58–60 HRC; 8566 is harder.
2) Toughness differs: LG’s toughness is 8–9 times that of DC53—it’s so tough that it won’t break even if you bend it; 8566’s resistance to chipping is 4 times that of high-speed steel SKH-9 and 2 times that of D2; LG has better toughness than 8566.
3) Wear resistance differs: Because 8566 has a higher total alloy content and greater hardness, it offers better wear resistance.
4) Resistance to hot metal erosion differs. As verified by die-casting experts, LG mold steel outperforms H13, SKD61, 2344, 8418, and others. In the field of die-casting molds, LG has a broader and more extensive range of applications than 8566.
5) Heat resistance differs; 8566 has a very high molybdenum content in its heat-resistant alloy, making its heat resistance twice that of LG.
6) High-temperature strength differs; because 8566’s heat-resistant alloy has high hardness, its high-temperature strength is naturally superior.
7) Resistance to thermal wear: 8566 offers high heat resistance, high hardness, a high total alloy content, and excellent resistance to thermal wear, resulting in a long service life when used in hot forging. As Mr. Zhang mentioned, when hot forging 304 stainless steel, 8566 receives a five-star rating—the finished product has excellent surface finish, resembling that of a tube, a performance that other die steels simply cannot match.
8) The heat treatment processes differ. The heat treatment process for 8566 is complex; we use a dedicated furnace and our own proprietary heat treatment process. If you purchase 8566 die steel, be sure to have it heat treated upon receipt.
9) Different Areas of Expertise. LG offers high toughness and is primarily used in applications with exceptionally high toughness requirements but no particularly high wear resistance requirements, such as cold extrusion dies for copper and aluminum, molds for glass-fiber-reinforced plastics, fine cores in plastic molds, PING pins for connectors, and aluminum extrusion dies.
8566 is primarily used in chipping scenarios that high-hardness mold steels cannot resolve. With a hardness of 58–60 HRC, it is specifically designed to address chipping issues that high-hardness mold steels such as D2, DC53, and SKH-9 cannot overcome. It is used to resolve chipping issues in stainless steel stamping, sharp-corner stamping, narrow-flange stamping, and even cases where the punch width is less than the sheet thickness or the stamping ratio is less than 1:1—problems that standard die steels cannot handle.
8566 is also used in cold heading dies, dies subjected to external stamping forces, and hydraulic dies with fine patterns. Furthermore, 8566 is particularly widely used for punches in hot forging dies.
I am listing these properties today to help everyone remember them and facilitate material selection. When choosing a specific die steel, we must comprehensively consider the properties of the material being stamped, the die structure, the operating conditions of the die, and the performance requirements of the die itself. Only then can we match the die’s performance needs, and the best choice is the one that suits your specific operating conditions.
It’s also important to note that “LG” and “8566” are not national steel grades; they are our company’s proprietary designations—exclusive products of Yuhui. They are not publicly available and constitute our intellectual property. However, due to the exceptional performance of these two materials, their high market visibility, strong sales, and the fact that customers specifically request them, they have been widely copied by competitors across the internet and even serve as reference standards for certain major steel mills—a truly unprecedented phenomenon in the industry.
The performance specifications I have listed apply exclusively to Yuhui’s LG and 8566 and do not apply to the imitations. If you see these exact same specifications elsewhere, they have undoubtedly been copied and pasted from my content.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.