Cutting method and technology of wear-resistant thick steel plate
1, steel plate cutting methods include cold cutting and hot cutting
Cold cutting includes water jet cutting, shearing, sawing or abrasive cutting;
Thermal cutting includes oxygen fuel flame cutting (hereinafter referred to as "flame cutting"), plasma cutting and laser cutting.
2. Cutting test
Through the relevant process test, the general characteristics, cutting parameters and cutting thickness range of various cutting methods of steel plate are mastered.
3. Flame cutting of wear-resistant thick steel plate
The method is as simple as cutting ordinary low carbon and low alloy steel, but when cutting thick steel plates, it is necessary to prevent the generation of steel plate cutting cracks, and the following recommendations should be followed when cutting:
Cutting cracks: steel plate cutting cracks are similar to hydrogen induced cracks during welding, and if cracks occur on the cutting edge of the steel plate, they will appear within 48 hours to several weeks after cutting. Therefore, the cutting crack is a delayed crack, and the greater the thickness and hardness of the steel plate, the greater the tendency of cutting cracks.
Preheat cutting: The most effective way to prevent steel plate cutting cracks is to preheat before cutting. Before the flame cutting, the steel plate is usually preheated, and the preheating temperature mainly depends on the quality grade of the steel plate and the thickness of the plate. The preheating method can be carried out by the flame burner, the electronic heating pad, or the heating furnace. In order to determine the preheating effect of the steel plate, the temperature should be tested on the hot spot surface. Note: When preheating, the entire steel plate interface should be evenly heated to avoid local overheating in the area in contact with the heat source. If whole plate preheating is not possible, local preheating can be used instead.
Low-speed cutting: Another way to avoid cutting cracks is to reduce the cutting speed.
The use of low speed cutting methods to prevent cutting cracks, its reliability is not as good as preheating. It is recommended to preheat the cutting belt with the flame gun for several times before cutting, and the preheating temperature is about 100°C. The maximum cutting speed depends on the grade and thickness of the steel plate.
Special note: The combination of preheating and low-speed cutting methods can further reduce the incidence of cutting cracks.
Requirements for slow cooling after cutting: regardless of whether the steel plate is preheated before cutting, slow cooling after cutting will effectively reduce the risk of cutting cracks. After cutting, the warm parts are stacked and covered with thermal blankets to achieve slow cooling to room temperature.
Heating requirements after cutting: heating (low temperature tempering) immediately after cutting the thick steel plate, which can effectively eliminate the cutting stress (holding time can be 5min/mm), and is also an effective method and measure to prevent cutting cracks. Heating methods can also be used combustion gun, electronic heating pad and heating furnace, heating temperature should not exceed 200°C.
4, reduce the softening of steel plate measures
The softening resistance of steel mainly depends on its chemical composition, microstructure and processing method. In thermal cutting, when the temperature exceeds 200-250°C, the hardness of the wear-resistant steel plate will be reduced, and the smaller the part, the greater the risk of softening the entire part.
The best way to eliminate the risk of softening is cold cutting, such as water jet cutting or wire cutting, and if thermal cutting must be used, plasma or laser cutting with relatively small input is preferred.
Underwater cutting method: An effective method to limit and reduce the extent of the softening zone, by placing the steel plate underwater for cutting, or by spraying the cutting surface with water during cutting. Plasma or flame cutting is available using the underwater cutting method.
Underwater cutting has the following characteristics:
The cutting heat affected zone is small.
Prevent the hardness of the whole workpiece from decreasing;
Reduce cutting workpiece deformation;
The workpiece can be cooled directly after cutting.
Cutting method and technology of wear-resistant thick steel plate
1, steel plate cutting methods include cold cutting and hot cutting
Cold cutting includes water jet cutting, shearing, sawing or abrasive cutting;
Thermal cutting includes oxygen fuel flame cutting (hereinafter referred to as "flame cutting"), plasma cutting and laser cutting.
2. Cutting test
Through the relevant process test, the general characteristics, cutting parameters and cutting thickness range of various cutting methods of steel plate are mastered.
3. Flame cutting of wear-resistant thick steel plate
The method is as simple as cutting ordinary low carbon and low alloy steel, but when cutting thick steel plates, it is necessary to prevent the generation of steel plate cutting cracks, and the following recommendations should be followed when cutting:
Cutting cracks: steel plate cutting cracks are similar to hydrogen induced cracks during welding, and if cracks occur on the cutting edge of the steel plate, they will appear within 48 hours to several weeks after cutting. Therefore, the cutting crack is a delayed crack, and the greater the thickness and hardness of the steel plate, the greater the tendency of cutting cracks.
Preheat cutting: The most effective way to prevent steel plate cutting cracks is to preheat before cutting. Before the flame cutting, the steel plate is usually preheated, and the preheating temperature mainly depends on the quality grade of the steel plate and the thickness of the plate. The preheating method can be carried out by the flame burner, the electronic heating pad, or the heating furnace. In order to determine the preheating effect of the steel plate, the temperature should be tested on the hot spot surface. Note: When preheating, the entire steel plate interface should be evenly heated to avoid local overheating in the area in contact with the heat source. If whole plate preheating is not possible, local preheating can be used instead.
Low-speed cutting: Another way to avoid cutting cracks is to reduce the cutting speed.
The use of low speed cutting methods to prevent cutting cracks, its reliability is not as good as preheating. It is recommended to preheat the cutting belt with the flame gun for several times before cutting, and the preheating temperature is about 100°C. The maximum cutting speed depends on the grade and thickness of the steel plate.
Special note: The combination of preheating and low-speed cutting methods can further reduce the incidence of cutting cracks.
Requirements for slow cooling after cutting: regardless of whether the steel plate is preheated before cutting, slow cooling after cutting will effectively reduce the risk of cutting cracks. After cutting, the warm parts are stacked and covered with thermal blankets to achieve slow cooling to room temperature.
Heating requirements after cutting: heating (low temperature tempering) immediately after cutting the thick steel plate, which can effectively eliminate the cutting stress (holding time can be 5min/mm), and is also an effective method and measure to prevent cutting cracks. Heating methods can also be used combustion gun, electronic heating pad and heating furnace, heating temperature should not exceed 200°C.
4, reduce the softening of steel plate measures
The softening resistance of steel mainly depends on its chemical composition, microstructure and processing method. In thermal cutting, when the temperature exceeds 200-250°C, the hardness of the wear-resistant steel plate will be reduced, and the smaller the part, the greater the risk of softening the entire part.
The best way to eliminate the risk of softening is cold cutting, such as water jet cutting or wire cutting, and if thermal cutting must be used, plasma or laser cutting with relatively small input is preferred.
Underwater cutting method: An effective method to limit and reduce the extent of the softening zone, by placing the steel plate underwater for cutting, or by spraying the cutting surface with water during cutting. Plasma or flame cutting is available using the underwater cutting method.
Underwater cutting has the following characteristics:
The cutting heat affected zone is small.
Prevent the hardness of the whole workpiece from decreasing;
Reduce cutting workpiece deformation;
The workpiece can be cooled directly after cutting.
