1.Soil abrasive particles and medium
The aggravation of wear at each wear part of tractor track shoe is closely related to the characteristics of soil abrasive particles and medium conditions. According to the measurement of energy spectrum probe, the soil is widely distributed on the wear surface, especially in the pit area. In addition, the influence of water and corrosive medium in soil is also great. In paddy field, the first consideration may be corrosion and wear. This problem is particularly prominent in the pin hole. The pin hole and the pin shaft are constantly sliding and rolling relative to each other, which accelerates the wear of the corrosive surface layer. The fresh worn surface is corroded by the atmosphere and moisture again during parking. This cycle accelerates the damage of tractor track shoes. At the same time, due to the large soil resistance in the paddy field, the pin hole part bears the tension. In the paddy field soil, the pin hole is easy to deform and pull into a trumpet shape and be scrapped.
2.Selection of tractor track shoe materials
At present, it is generally believed that the track shoes of high manganese steel tractors can not be fully work hardened, the service life potential can not be brought into full play, and the service life in paddy fields is very low. At present, several alternative materials tested can not fundamentally solve the problem of paddy field corrosion and wear. Relatively speaking, M7 material, especially after dispersion treatment, has better work hardening degree than high manganese steel because it reduces the stability of austenitic manganese steel. It shows good wear resistance in paddy field. Therefore, the track shoe of M7 tractor is effective in paddy field. The current problem is to solve the problem of brittle fracture in dry field.
For dry field operation, the selection of materials is based on the premise of improving the hardness as much as possible on the basis of ensuring a certain toughness without fracture. Higher hardness and yield limit are beneficial to resist micro cutting and rolling deformation. 31mn2si has quite high hardness (HRC45-50) and yield limit value（ σ S = 14-16mpa), which is beneficial to wear resistance. The future direction is how to improve its plasticity and toughness, especially its ability to resist the occurrence and development of microcracks. The wear resistance of nodular cast iron isothermal quenching tractor track material is still good, but due to the unstable casting quality, there are many fractures in actual use, which limits its use.