The boss consulted that the hexagonal nut hot forging die of rebar is produced by automatic hot forging, and 20,000 products are made a day. The bottom mold is made of H13 mold steel with a hardness of about 50.
Sometimes the H13 ejector rod (top core) can be beaten for a day, but the surface of the mold is particularly cracked, and there are many small cracks. After lowering the surface, it will be used for another day, and the ejector rod (top core) can only make a few thousand more products, and then the whole will crack. What are the more durable die steels you are looking for now? [Yuhui Mould Steel Huang Zipeng's Diary No. 760]
The boss's ejector rod (top core) is in the bottom mold, and the ejector rod is also inlaid with tungsten steel.
After watching the work video of the boss, the rebar is heated to a whitish color, and the temperature is relatively high. When the ejector rod (top core) is in direct contact with the forging, it has been heated, and it has to withstand the pressure of a 200-ton punch, which requires the heat resistance, strength and toughness of the die steel.
The surface of the die steel with poor heat resistance is annealed quickly, and early thermal fatigue cracks will appear on the surface after many times of alternating between cold and heat.
Moreover, the ejector rod (top core) should fully bear the pressure of molding, and the mechanical stress is large, and there is no hardness, which will cause the thermal fatigue crack to extend to the inside of the mold very quickly.
The heat-resistant element molybdenum content of H13 is low, the alloy has a low degree of strengthening, and the strength and toughness of the alloy are not enough at high temperature to inhibit the appearance and development of cracks. Therefore, it is recommended that the boss use more heat-resistant 8433 mold steel.
8433 die steel is smelted by atmosphere protection electroslag furnace, and the sulfur content of harmful impurities that are easy to decompose at high temperature in the steel is very low, which reduces the source of early thermal fatigue and internal cracking of the die steel.
The heat resistance of 8433 die steel is 2-3 times that of H13, and the mold can maintain high hardness for a long time, and there will be no rapid collapse and thermal deformation. The hardness is HRC50-54, high temperature strength, and toughness, which can effectively inhibit the development of thermal fatigue cracks, and is commonly known as good crack resistance.
I remember that in March this year, I went to visit the customer's factory in Zhejiang. He has been producing a part in white goods for a long time, and the workshop has to finish the blank into the finished product. In the pre-forging process, the 35 steel round bar should be heated and flattened into a disc.
At the beginning, the mold core was inlaid tungsten steel, which was able to produce more than 100,000 products. Later, it was transformed into manipulator automatic forging production, and the mold core was changed to inlay H13.
Although the mold core of H13 has been soaked in water for cooling, it is often played for about 2 hours, and there are many cracks and reaming holes on the edge of the mold core.
The boss has to work more than 5,000 pieces in one shift, and he has to work 2 shifts a day. If the life of the mold is unstable, the master often has to replace the mold, and the mold has to be repaired and opened all the time, and the workshop will be inefficient.
The boss began to experiment with different die steels. After replacing Yuhui 8433 mold steel, the life of a single mold can be more than 10,000 pieces, and often 20,000 pieces of products are replaced by molds.
Because the effect is good, the life of the mold is stable and long enough, and the boss is dozens or dozens of pieces of orders to go back to use.
There are also many bosses who do hot forging of screws, hot forging of flanges, hot forging of large mechanical parts, and high requirements for the thermal stability of the mold, all of which are using 8433 die steel. More than 100 of the world's top 500, listed companies, large and medium-sized auto parts factories such as Valeo, South China Precision Forging, Sanlian Forging and so on are our users.
I am Huang Zipeng, from Liaobu, Dongguan. Yuhui die steel, 3 of the world's top 500 are in use, Kyocera has purchased for 7 consecutive years.
If the boss in front of the screen also has a similar rebar hexagon nut hot forging die H13 top rod cracking serious working conditions, you can also come to Yuhui die steel Huang Zipeng to try it.