Crusher blow bars (also known as hammer) is the main wear part of horizontal shaft impact crusher, is also an important factor affecting cost. The hammer acts by striking the material entering the crushing chamber and throwing it against the impact wall, thereby breaking the material into smaller particles. The hammer wears out gradually during striking the material and needs to be replaced. They are made of cast steel and contain a variety of metallurgical components optimized for specific applications. The material of the hammer has been adjusted differently for different working conditions. High manganese blow bar is a material invented for specific working conditions.
Why Manganese Steel?
manganese steel is a unique non-magnetic steel with extreme anti-wear properties. The material is very resistant to abrasion and will achieve up to three times its surface hardness during conditions of impact, without any increase in brittleness which is usually associated with hardness. This allows manganese steel to retain its toughness. Because of this characteristic of high manganese steel, it is very suitable for making the blow bars of impact crusher.
Manganese Blow Bars’ Applicable Conditions
Properties: Manganese steels are used in conditions where greater resistance to impact or tension is required. When impact forces are high, the manganese steel material of the hammer is reinforced (cold-set) to reduce wear.
Recommended for:
- Less abrasive materials such as limestone
- In case of very large feed size
- When the feeding material contains a large amount of non-breakable material (e.g., iron), or when the use of other hammers is not cost effective
Grade and Chemical Composition of Manganese Blow Bars
| Grade | Chemical Composition (%) | ||||||||
| C | Si | Mn | Cr | Mo | Ni | Cu | S | P | |
| ZG12OMnl3Cr2 | 1．05～ 1．35 | O．3～ 0．9 | 11～ 14 | 1．5～ 2．5 | ≤ l.O | / | / | ≤ 0．04 | ≤ O．06 |
| ZG12OMnl7Cr2 | 1．05～ 1．35 | O．3～ 0．9 | 16～ 19 | 1．5～ 2．5 | ≤ l.O | / | / | ≤ 0．04 | ≤ O．06 |
Note: This is only a standard chemical composition. The actual chemical composition needs to be adjusted according to the customer’s working conditions.
Metallographic Organization and Mechanical Properties
- Surface hardness: ≤ 300 HBW
- After impact hardening: around 55-60 HRC
- Impact power: ≥ 90J
Heat Treatment of Manganese Blow Bars
The principle of heat treatment of high manganese steel is that the supercooled austenite is obtained by cooling the structure after heating and holding the heat, that is, the high temperature austenite structure is kept to room temperature. When the heated workpiece is cooled in static water, about 800~400 °C, the vapor film is formed on the surface and enters the vapor film cooling stage, at which time the heat transfer is relatively slow; When it was cooled to about 300 °C, the steam film was broken and the cooling rate increased sharply. The boiling disappears when the temperature is below 100 °C, and the convection cooling stage is entered. SODIUM CHLORIDE can decrease the stability of the vapor film, promote the rupture of the vapor film, increase the characteristic temperature, increase the maximum cooling rate to 500 °C, increase the cooling capacity and increase the cooling rate.
No just Manganese Blow Bars!
In order to solve the defect of short service life of high manganese steel blow bars. Our engineers have developed a process of embedding titanium carbide with high manganese steel blow bars.
With the same working conditions, the service life of the newly designed manganese blow bars can be increased by 150% ~ 200%.
