A lot of research has been done on the changes of mechanical properties and microstructure of bainitic Martian multiphase wear-resistant cast steel under different heat treatment processes. However, the wear-resistant mechanism of bainitic Martian multiphase wear-resistant cast steel is not clear. Wear resistance is not an inherent physical property of steel materials, but a series of complex engineering problems, which are closely related to the stress state of steel materials, physical morphology of surface, physical properties of abrasive medium and dual medium, working environment and other problems, The microstructure and properties of wear-resistant steel materials are one of the important factors. The bainite Martian multiphase wear-resistant cast steel was compared with mnl3cr2 wear-resistant steel, which is the most widely used high manganese steel in the field of wear-resistant lining plate. The two-body and three-body wear experiments were carried out by MM-W1A universal wear tester and MLD-10 impact abrasive wear tester respectively. The neutral salt spray experiment was designed to corrode the experimental steel, and then through the impact abrasive wear experiment, the microstructure evolution law and wear behavior of the experimental steel under different experimental conditions were explored, and a multi-dimensional wear analysis method was proposed, which described the wear behavior of the material from four dimensions and reflected the severity of wear through the wear dimension, Thus, the wear-resistant mechanism of Bei Ma multiphase wear-resistant cast steel is clearly explained, which lays a theoretical basis for the further practical application and popularization of Bei Ma multiphase wear-resistant cast steel.
(1) In the two body pin disc wear test, the wear resistance of bainite multiphase wear-resistant cast steel is nearly three times that of mnl3cr2; In the three body impact abrasive wear test, the wear resistance of bainite Martian multiphase wear-resistant cast steel is 38%, 99% and 246% higher than mnl3cr2 at 1J, 2J and 4J, respectively; In the three body impact abrasive wear test after salt spray corrosion, the wear resistance of bainite Martian multiphase wear-resistant cast steel decreased by 10%, 42%, 54%, 57% and 58% respectively after salt spray corrosion for 1h, 2h, 4h, 8h and 24h.
(2) A multi-dimensional wear analysis method is proposed to explain the wear mechanism of bainite Martian multiphase wear-resistant cast steel. One dimensional wear analysis describes the microstructure evolution and work hardening along the normal direction of the wear surface. Twinning, high-density dislocation and retained austenite transformation are the strengthening mechanism of bainite Martian multiphase wear-resistant cast steel, which has obvious advantages in wear resistance. The work hardening mechanism of mnl3cr2 is dislocation entanglement and stacking fault.
(3) The two-dimensional wear analysis describes the wear mechanism on the two-body friction and wear surface. Mnl3cr2 with low strength is prone to deformation and spalling, and its wear form is mainly adhesive wear. Therefore, the two-body friction and wear performance is far lower than that of bainite Martian composite wear-resistant cast steel with abrasive wear.
(4) The three-dimensional wear analysis explains the wear mechanism on the three body impact abrasive wear surface. Strain fatigue, crack, furrow, embedded abrasive particles and extrusion accumulation are the main wear mechanisms of bainite Martian multiphase wear-resistant cast steel. Embedded abrasive particles, furrow, strain fatigue, cutting, extrusion accumulation and spalling pits are the main wear mechanisms of mnl3cr2. The difference of wear mechanism is due to the difference of yield strength and initial hardness.
(5) The corrosion products accounted for 26.6%, 47.5%, 72.4%, 79.5% and 98.8% of the sample surface after salt spray corrosion for 1h, 2h, 4h, 8h and 24h, respectively. During salt spray corrosion for 1-4h, the corrosion rate of the sample increases continuously, and decreases from 8h. In the early stage of salt spray corrosion, pitting corrosion mainly occurred, and the rust was loose and discrete. At 4h, the corrosion products increased significantly, and the morphology was mostly needle flocculent. From 8h, the corrosion products became dense and connected together, the color was dark red of iron oxide, and the morphology was cluster, forming a dense rust layer to cover the metal matrix.
(6) The four-dimensional wear analysis explains the wear behavior under the combined action of salt spray corrosion and impact abrasive wear. The wear mechanism of 1H salt spray corrosion specimen in impact abrasive wear test is still characterized by furrow, strain fatigue and embedded abrasive particles. After that, with the extension of salt spray corrosion time, the strength of metal matrix decreases, so it is easier to be moved and cut, the furrow becomes shorter and deeper, and the wear weight loss increases. When salt spray corrosion for 0-2h, the width of the deformation zone of the worn sub surface of the sample increases gradually. When the salt spray corrosion lasts for more than 8h, the impact energy is dispersed and absorbed by the corrosion products, the metal matrix can not be effectively strengthened, delamination and spalling failure occur, and the wear resistance of the material deteriorates. A theoretical formula is established to estimate the wear weight loss of bainitic Martian multiphase wear-resistant cast steel under the synergistic action of salt spray corrosion and impact abrasive wear: F = 0.0611nt + 0.077t + 0.0722