Improvement of wear resistant casting bucket teeth of excavator

1. Improvement of structure

From the actual failure of the bucket teeth, it is found that the tooth tip is the most easily worn place in theory, but a part of the bucket teeth failure is broken from the middle, which shows that the structure of the bucket teeth directly affects the service life of the bucket teeth. The tooth structure includes the angle of installation and use of the tooth and the appearance of the tooth itself. These factors can be simulated by the simulation analysis software, and then the structure of the bucket tooth can be optimized to improve the service life of the bucket tooth and save the production cost. Yang lie et al. Made improvements in the bucket tooth structure. The improved bucket tooth structure is simple. The improved bucket tooth structure eliminates some shortcomings of the existing bucket tooth structure. The structure is simple and easy to process and manufacture. When the tooth pin falls off or the bucket tooth is worn out, it can save users precious construction time.

2. Material improvement

At present, the commonly used materials for making bucket teeth are high manganese steel anti-wear bucket teeth and medium and low-carbon low-alloy wear-resistant bucket teeth. High manganese steel materials have a history of 100 years (the composition is C09% – 12%, MN11% – 14%, SI) The strength of single-phase austenite after water toughening treatment is not high (the strength is less than 680mpa), but it has higher impact toughness than other casting materials. Its anti-wear mechanism is that the single-phase austenite will undergo extremely strong cold work hardening under severe impact and extrusion conditions, which promotes the surface hardness of parts from hv20 to hv20 High wear resistance was obtained by increasing the wear resistance to HV500. Therefore, the bucket teeth of high manganese steel are suitable for digging materials with hard, strength and high wear capacity. However, the yield strength of high manganese steel is low, and it is easy to bend and deform under impact and extrusion. Therefore, many countries have done a lot of research on improving the strength and toughness of high manganese steel, mainly adding alloying elements (such as adding CrNi) Mo) and microalloying method (such as adding V, Ti, Nb, re, etc.) to make high manganese steel.

Low carbon alloy steel bucket teeth are mainly used in the process of digging soft materials. Through strengthening the bucket teeth with alloy elements and improving the hardenability, the bucket teeth can obtain overall high hardness after material heat treatment to improve the wear resistance. Generally, the carbon content is about 0.2%. Cr Ni Mo, Cr Mo and CrMn Mo types are used for this kind of bucket teeth abroad. After quenching, the tempering structure is martensitic. Low carbon low alloy martensitic steel has good strength and toughness, especially suitable for thin, long and sharp bucket teeth.

In conclusion, low carbon and low alloy materials have advantages over high manganese steel in improving the comprehensive properties of bucket teeth.

3. Improvement of heat treatment process

Heat treatment process plays an important role in the shape and distribution of carbides in high manganese steel, thus affecting the service life of the material. High manganese steel along the grain boundary distribution of bar, sheet, needle like carbides, these shapes of carbides are very harmful, but block, spherical needle like carbides distributed in the grain or inside the grain boundary can also play a role in increasing hard points and improving wear resistance. Therefore, reasonable heat treatment process has important research value for improving the comprehensive properties of high manganese steel.

In order to obtain the required metallographic structure during heat treatment of low alloy materials, low carbon low alloy steel adopts solution spheroidizing annealing to make the carbide in the structure become uniform and fine, and improve the mechanical properties of the material. The low carbon low alloy steel is quenched and tempered at low temperature to obtain lath martensite. It is one of the ideal materials to resist abrasive wear under high load and high impact load Compared with zgmnl3, the steel has better wear resistance, longer service life, better market competitiveness and greater economic benefits.

As mentioned above, the bucket teeth must meet the following requirements in use, with high bending strength, resistance to various stresses, good comprehensive mechanical properties, high hardness and high wear resistance.