On Monday, as soon as I got to work, I received a bank transfer from Mr. Ying for 10 pieces of heat-resistant steel 8433. Seeing such a large order come in immediately lifted my spirits.
Since last June, Mr. Ying has been placing orders for heat-resistant steel 8433 from time to time, usually in batches of 10 or 8 pieces. His willingness to continue placing repeat orders indicates that he recognizes the performance of heat-resistant steel 8433 and is satisfied with the mold life it provides.
On June 6, 2025, Mr. Ying contacted me. He specializes in forging high-temperature stainless steel materials such as austenitic, martensitic, and nickel-based alloys. He is now looking for a reliable mold steel that can withstand the demands of his process, with a required mold life of over 10,000 pieces. The workpieces weigh 0.5 to 2 kilograms and are processed on a 630-metric-ton double-disc friction press. The workpieces are heated to 1,000–1,050°C, and the process consists of four steps: reducing diameter, forming, trimming flash, and trimming. Previously, H13 die steel was used, but its service life was relatively short; after about 1,000 strokes, the die began to deform, develop corner collapse, and crack. Please help recommend suitable die steel materials, heat treatment processes, and methods for die repair and maintenance.
Since his die structure is an upper-and-lower die design with a stepped surface, it requires good toughness; the die as a whole uses a significant amount of steel, so the cost cannot be too high; various types of stainless steel are forged at high temperatures, which places extremely high demands on the die steel’s heat resistance and thermal stability, so a die steel with excellent heat resistance must be selected.
Currently, H13 begins to deform, experience corner collapse, and develop cracks after about 1,000 cycles. This is because H13 has poor heat resistance; the mold is annealed during use, causing a drop in hardness and a loss of red hardness, which leads to failure in the form of deformation, corner collapse, and cracking. Improving the heat resistance of the mold steel is key, so I recommended the heat-resistant steel 8433 at the time.
The heat resistance and stability of 8433 die steel are 2–3 times that of H13, with a hardness of HRC 50–54. Throughout its service life, the die will not anneal, its hardness will not decrease, and its red hardness is guaranteed. This eliminates the two major persistent problems of die collapse and cracking. It is particularly worth emphasizing that the service life of 8433 dies does not decrease after repair; even if a die is repaired to the point of scrapping, the hardness on the back surface will not decrease. A customer used this steel to hot-forge deep-drawn 45 steel products. After four surface regrinding operations, the mold’s service life remained unchanged, with each cycle lasting 10,000 strokes.
8433 is a proprietary heat-resistant steel developed by Yuhui Mold Steel. It far surpasses competing products in multiple performance metrics—including high heat resistance, fatigue resistance, and thermal conductivity—and its performance is second to none. Because 8433 prevents mold collapse and cracking, mold life is significantly extended, downtime for mold repairs is reduced, automated forging efficiency is maximized, and costs are drastically lowered. Currently, over 100 companies—including Valeo, South China Precision Forging, and Sanlian Forging—as well as Fortune 500 companies, publicly traded firms, and large and medium-sized automotive parts manufacturers—are using it.
From June 6, 2025, to the present—a full year has passed—Mr. Ying’s willingness to make frequent purchases clearly indicates that the service life of 8433 heat-resistant steel is definitely longer than that of H13. Since he needs fewer mold repairs and his efficiency has improved, he continues to place orders—and in bulk.
Repeat orders from long-time customers are always a pleasure. After a year has passed, I feel it’s time to document this case.
When hot-forging dies suffer from collapse or cracking, using 8433 die steel is even more satisfying than eating braised pork!
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.