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Sawing processing and sawing machine selection of high manganese steel

High manganese steel

Steel with a manganese content of 11% to 18% is called high manganese steel. The chemical composition of commonly used cast high manganese steel ZMn13 is: Mn content is 11% to 14%, C content is 1% to 1.4%, Si content is 0.3% to 1%, P content is less than 0.03%, and S content is less than 0.05% . High manganese steel is a kind of wear-resistant steel. The high manganese steel that has been treated with water toughness can obtain better plasticity and impact toughness. The high manganese steel that has been water toughened is called high manganese austenitic steel. Its mechanical properties: tensile strength=980MPa, yield strength=392MPa, hardness of 210HB, ak=2.94MJ/m2. Although the hardness of high manganese steel is only 210HBW, its yield point is low, only 40% of the tensile strength, so it has high plasticity and toughness.

High manganese steel is divided into high carbon high manganese wear-resistant steel, medium carbon high manganese non-magnetic steel, low carbon high manganese stainless steel and high manganese heat resistant steel.

The grades of high manganese steel commonly used in China: ZGMn13-1 (C:1.10%~1.50%) is used for low-impact parts, ZGMn13-2 (C1.00%~1.40%) is used for ordinary parts, and ZGMn13-3 (C0. 90%~1.30%) is used for complex parts, ZGMn13-4 (C0.90%~1.20%) is used for high-impact parts, ZGMn13-5, 50Mn18Cr4V for motor guard ring, etc.

Cutting characteristics of high manganese steel
(1) Work hardening is particularly serious. In the cutting process of high manganese steel, due to the large plastic deformation, the austenite structure transforms into a fine-grained martensite structure, resulting in severe hardening. The hardness can be increased from 210HB to more than 500HB, which is 2.5 higher than the hardness of the matrix. The depth of the hardened layer can reach 0.1~0.3mm. This not only increases the cutting force and cutting heat, but also aggravates the wear of the tool and brings difficulties to the next cutting process. Its hardening degree and depth are several times that of cutting 45 steel.
(2) The cutting force is large. According to relevant literature, the unit cutting force of 3800MPa/mm2 when cutting ZGMn13 is about 60% larger than the unit cutting force of 2300MPa/mm2 for cutting 45 steel.
(3) The cutting temperature is high. Due to the high cutting force and cutting power of cutting high manganese steel, more heat is generated. In addition, its thermal conductivity is small, only about 1/4 of the thermal conductivity of 45 steel, so the temperature in the cutting zone is very high. When the cutting speed Vc≤50m/min, the cutting temperature of high manganese steel is 200~250℃ higher than that of cutting 45 steel.
(4) Difficult chip breaking. The toughness of high manganese steel is 8 times that of 45 steel, and the elongation is also very large, resulting in large deformation coefficient and cutting force. During cutting, the chips are not easy to break, which brings great difficulties to chip handling.
(5) Machining accuracy is not easy to guarantee. Due to the high linear expansion coefficient of high manganese steel, under the action of cutting heat, it is easy to produce thermal deformation, which affects the machining accuracy of the workpiece.

Cutting characteristics of high manganese steel

(1) Work hardening is particularly serious. In the cutting process of high manganese steel, due to the large plastic deformation, the austenite structure transforms into a fine-grained martensite structure, resulting in severe hardening. The hardness can be increased from 210HB to more than 500HB, which is 2.5 higher than the hardness of the matrix. The depth of the hardened layer can reach 0.1~0.3mm. This not only increases the cutting force and cutting heat, but also aggravates the wear of the tool and difficulties to the next cutting process. Its hardening degree and depth are several times that of cutting 45 steel.

(2) The cutting force is large. According to relevant literature, the unit cutting force of 3800MPa/mm2 when cutting ZGMn13 is about 60% larger than the unit cutting force of 2300MPa/mm2 for cutting 45 steel.

(3) The cutting temperature is high. Due to the high cutting force and cutting power of cutting high manganese steel, more heat is generated. In addition, its thermal conductivity is small, only about 1/4 of the thermal conductivity of 45 steel , so the temperature in the cutting zone is very high. When the cutting speed Vc≤50m/min, the cutting temperature of high manganese steel is 200~250℃ higher than that of cutting 45 steel.

(4) Difficult chip breaking. The toughness of high manganese steel is 8 times that of 45 steel, and the elongation is also very large, resulting in large deformation coefficient and cutting force. During cutting, the chips are not easy to break, which brings great difficulties to chip handling.

(5) Machining accuracy is not easy to guarantee. Due to the high linear expansion coefficient of high manganese steel, under the action of cutting heat, it is easy to produce thermal deformation, which affects the machining accuracy of the workpiece.

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