If you’re making a die with a TD coating, I strongly advise against using Cr12MoV tool steel—the chances of failure are very high.
I just received an inquiry from a user: they bent 5mm duplex stainless steel into a W-shape using a Cr12MoV die with a TD coating costing 80 yuan per kilogram, but after stamping only 20 parts, the die started producing string marks, leaving streaks all over the products, which were deemed unqualified. Now they’re unsure what die steel to use.
After a mold is coated, its surface hardness increases and surface finish improves. This can resolve the issue of stringing caused by wear that degrades surface finish. However, if you choose the wrong base material—one with severe segregation or too many microcracks—the coating cannot cover these defects. In that case, even with the coating, the stringing problem will persist.
Cr12MoV is very inexpensive, but if the coating costs 80 yuan, the material cost alone comes to over 100 yuan. If stringing occurs after just 20 products, it’s as if the mold was made for nothing, the coating was applied for nothing, and the mold steel was wasted—this represents a significant loss.
The idea of applying a coating to improve the mold’s wear resistance is sound, but it’s crucial to choose the right base material. Don’t use Cr12MoV for coating—the likelihood of failure is very high. Even when people use DC53 for coating, failures still occur.
One user was drawing 1.2-mm stainless steel with a 1.2-meter-long die made of SKD11 + TD. After just 500 products, scratches started appearing—a massive loss. With material costs, heat treatment, and coating fees totaling over 100 yuan per kilogram, the die was scrapped after only 500 products, leaving the boss in tears.
If you’re going to apply a coating, you absolutely must use at least DC53. Although many people have had issues with DC53 coatings, the failure rate is much lower than with Cr12MoV.
If you don’t want to use DC53, you can use wear-resistant steel 6077, which has a hardness of 60–63 HRC and three times the toughness of chromium steel.
We have a customer who deep-draws 0.7 galvanized steel motor housings with a draw depth of 30 mm. Using DC53 tends to cause wire drawing, but with wear-resistant steel 6077, we’ve produced 3 million units without a single die failure. Although wear-resistant steel 6077 may eventually develop wire marks over time, I can simply polish it to restore its usability. Since this happens infrequently, customers don’t complain—and when customers don’t complain, we’re all happy.
Third option: If your budget allows and you want better coating performance, you can use 8503 die steel, which prevents material sticking.
8503 has a hardness of 59–61 and twice the toughness of DC53. Compared to DC53, its performance doubles without doubling the price, plus it offers the added benefit of non-stick properties. For our drawing dies, the biggest concern is adhesive wear caused by material sticking, which leads to stringing on the products. If you use 8503 with a coating, the results will be much better than those achieved with DC53 or wear-resistant steel 6077.
Of course, that’s just my opinion. When deciding which material to use, you’ll need to weigh your mold production costs and local supply chain availability.
However, for molds requiring a coating, I sincerely advise against using Cr12MoV or SKD11—the risk of failure is far too high. Coating costs are several times that of the mold steel itself, and if the mold fails, the losses are enormous; it simply isn’t worth it.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.