Mechanism of Cutting Delayed Cracks in Thick NM500 Wear-resistant Steel Plates
The factors leading to delayed cracks in the cutting process of NM500 wear-resistant steel plate are mainly two aspects. The first is that in the cutting process of NM500 wear-resistant steel plate, because the thermal expansion and contraction of the cutting material is larger than the cutting material, so the thermal stress produced in the cutting is relatively large, and the tensile stress at the cutting incision is much larger than the tensile stress. If the NM500 wear-resistant steel plate is cooled rapidly, the thermal stress generated in the cutting process will not be released in time, resulting in the formation of delayed cracks in the cutting area. On the other hand, as the NM500 wear-resistant steel plate is usually formed by thermosplastic forming, it will contain a large amount of residual internal stress. During the cutting process of the NM500 wear-resistant steel plate, when cutting force is applied, the internal stress of the material is further increased, and the tensile stress at the cutting incision will be greatly increased, which is also one of the main causes of delayed cracks.
To prevent delayed cracks in the cutting process of NM500 wear-resistant steel plate, in addition to improving the cutting parameters and optimizing the cutting technology, preheating treatment before the cutting process of the NM500 wear-resistant steel plate is an important measure. Through the preheating treatment with a suitable heating time and temperature, the thermal stress of the NM500 wear-resistant steel plate can be released, the cutting force is reduced, the cutting force at the edge of the incision is reduced, and the tensile stress generated in the cutting process is reduced. It can also reduce the residual internal stress of the material and reduce the chance of delayed cracking after the material cutting.
In addition, in order to NM500 wear-resistant steel reduce the tendency of delayed cracks caused by cutting force, it is necessary to provide reasonable chip evacuation measures to ensure a smooth chip evacuation process, reduce the load in the zone and avoid high local stress. For the cutting area of high stress, reasonable cutting position should be chosen to reduce the pressure of cutting force on the cutting section and reduce the chance of delayed cracking.
In addition, reasonable collimation and reasonable choice of blade angle should also be taken into consideration. The reasonable choice of blade angle can shorten the cutting area and reduce the cutting force. In the same way, reasonable collimation can reduce the cutting force and improve the cutting quality. At the same time, the common inclination angle between the blade and the workpiece surface should be set as far as possible to improve the cutting quality and reduce the cutting force.
Furthermore, reasonable selection of cutting fluids is also important to reduce the risk of delayed cracking. Cutting fluids can reduce cutting temperature, reduce tool and workpiece wear, eliminate friction between tool and workpiece, and protect tools from oxidation. In the cutting process of NM500 wear-resistant steel plate, if a suitable cutting fluid is selected, the cutting force can be reduced and the formation of delayed cracks caused by cutting force can be avoided to a certain extent.
In summary, cracking crack in the cutting process of NM500 wear-resistant steel plate is an inevitable problem in the engineering application, which not only affects the quality and efficiency of the product, but also causes potential safety hazards and industrial production losses. Therefore, it is necessary to take reasonable measures to reduce the risk of delayed cracking and ensure the quality of machining.
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