Purchasing tool steel and purchasing ordinary steel plates are two completely different things. The wrong choice of ordinary steel plate is nothing more than changing the batch, the wrong choice of tool steel, the collapse of the mold and the broken tool, and the loss of tens of thousands of pieces when the production line stops.
However, many purchases are easy to fall into a misunderstanding: the expensive ones are definitely good, or just look at the brand number regardless of the use. Today, let's make it clear that D2, H13, O1 and M2, the four most common tool steels, have their own unique skills. Choosing the right one means saving money, and choosing the wrong one means wasting.
Make clear the core logic of tool steel first.
Tool steel doesn't compete for strength like ordinary steel plates. It competes for three things: wear resistance, toughness and heat resistance. And these three things are usually you can't have your cake and eat it. If you want to wear resistance, you have to sacrifice a little toughness; If you want to resist high temperature, it may be soft at room temperature. So no steel is the "best", only the "most suitable".
What are the four common brands?
D2: High-carbon and high-chromium cold-working steel. Its greatest advantage is its strong wear resistance. The molds and blades made of it will not wear for a long time, and the hardness can reach HRC 60-64. But the price is that it is brittle, has poor impact resistance and is easy to crack under severe impact. Suitable for stamping dies, shear blades and other parts that need long-term friction but are not subject to severe impact.
O1: Oil quenching is a panacea in tool steel. Toughness is better than D2, and it is easier to process. The hardness is about HRC 57-62, but the wear resistance is not as good as D2. Suitable for ordinary tools, fixtures, measuring tools, which are not particularly demanding but need good processing.
H13: Hot working steel, specially designed for high temperature environment. It can maintain hardness at high temperature of 700-800 Baidu, and it is not easy to crack. The hardness at room temperature is only HRC 46-52, which is softer than the first two. It is mainly used in die casting dies and hot forging dies where high temperature is needed. If you don't use it at high temperature, buying H13 is a waste of money.
M2: High-speed steel, which can keep sharp even under high-speed cutting. When running at high speed, friction generates heat, and ordinary tool steel soon softens, but M2 has good heat resistance and can withstand it. Hardness HRC 62-64, similar to D2. Suitable for high-speed cutting tools such as drill, milling cutter and tap. The price is not cheap, and the cost of containing tungsten and molybdenum is there.
The three most common mistakes in purchasing
- The first mistake: treat D2 as universal steel. D2 is really wear-resistant. Many people think that wear-resistance is good, so they use D2 for everything. However, D2' s carbide particles are large, so it is easy to crack when it is impacted. It's no problem to make a stamping die, but it may collapse after hundreds of times when it is used to make a cold forging die that needs stress.
- The second mistake: I think H13 has low hardness. H13 is soft at room temperature, and people who don't understand it think it is defective. In fact, its value is in a high temperature environment. Ordinary steel begins to soften at 400 degrees, and it can still work at H13 to 600 degrees. It's not used in hot places, and you shouldn't buy H13 at all.
- The third mistake: M2 is also used for ordinary cutting. M2 is really good, but expensive. Conventional processing of ordinary carbon steel, using M2 is to kill chickens. M2 is reserved for high-speed cutting or machining difficult-to-cut materials.
summary
Use cold and choose D2 when friction is the main occasion; Cold use but need toughness and good processing, choose O1; H13; is directly selected in high temperature environment; M2 is selected for high-speed cutting.
