Aluminum bronze is widely used in wear-resistant and corrosion-resistant parts because of its excellent wear resistance.A lot of research work has been done to improve its performance to adapt to increasingly harsh friction and wear conditions.In the development and coating of new aluminum bronze Researches on layer materials have also achieved many results. The content of aluminum (mass fraction,%, the same below) in conventional aluminum bronze is 5% to 12%, and the Al content in the new high aluminum bronze (Cu-14% Al-X) developed by Heda Copper Alloy has been increased to 14 % ～ 15%, also adding elements such as Fe, Ni, Mn, Co, and rare earth, the ideal structure can be obtained after heat treatment, and its physical, chemical, mechanical and friction and wear properties have been significantly improved, which can replace high alloy tool steel in Promotion and application on large metal drawing dies. This article uses microstructure analysis to systematically study the distribution of alloying elements in new high-alumina bronzes, the characteristics of precipitation phases, and their changes before and after heat treatment, and to associate the structural changes with their abrasion properties. Reasons for the increased wear resistance of the new high speed machining aluminum bronze.
Performance organization of aluminum bronze1.The new high-aluminum bronze sample is in the as-cast and heat-treated state, and its main chemical composition is 14.2% Al, 3.5% Fe, 0.6% Mn, 0.4% Ni, 0.8% Co, 0.2% Zn, 0.06% rare earth, and the balance Cu. The main chemical composition of as-cast aluminum bronze (QAl9-4) is 9.2% Al, 3.6% Fe, and the balance of Cu.
2. The test materials are smelted in an intermediate frequency furnace, released from 1200 ° C, poured at 1150 ° C, and cast by sand casting. The heat treatment process of high aluminum bronze is 920 ℃ × 2h (oil quenching) + 580 ℃ × 3h (air cooling). Metallographic sample size is 10mm × 10mm × 10mm; wear sample size is 50mm × 25mm × 10mm, surface roughness Ra = 0.4μm. Use the electronic probe to determine the micro-area composition of the sample; determine the phase composition of the sample with an X-ray diffractometer; observe the morphology of the structure with a metallographic microscope; determine the relative content of the κ phase with a standard quantitative metallographic method; use electrolytic deep etching The sample was prepared by scanning method, and the three-dimensional morphology of the phases in the sample was taken with a scanning electron microscope.
3.Use a Rockwell hardness tester to measure the microhardness of each phase; use a reciprocating abrasion tester to perform the wear test. The Si3N4 ceramic ball is 6mm, the wear scar length is 40mm, and the reciprocating frequency is 50r / min. 480m, load is 15 ~ 29N. The abrasion amount was obtained by the abrasion mass loss method, and the wear scar width was measured by a 2201 surface topography instrument for re-inspection. All the abrasion test data are the average of the three test results.
Wear properties of aluminum bronze1. The relationship between the wear and load of high-aluminum bronze and aluminum bronze under dry friction. The wear increases with the increase of the load, and the relationship is linear, which is in line with Rabinowicz's simplified model of abrasive wear. For high-aluminum bronze, whether it is heat treated or not, the amount of wear is much smaller than that of aluminum bronze under the same conditions, indicating that under dry friction conditions.
2. High-aluminum bronze has better wear resistance due to its higher hardness and strength (σb = 564MPa). The wear resistance of high-aluminum bronze after heat treatment is improved compared to the as-cast state. This is because although the κ phase is reduced, Fe is transferred to the matrix to strengthen the matrix, and the hardness is increased to improve the overall material's resistance to ploughing.
3. The Rabinowicz formula indicates that the weight loss is inversely proportional to the hardness. The average mass loss of as-cast and heat-treated high-aluminum bronzes with loads from 15N to 29N was measured to be 7.45mg and 6.73mg, with a ratio of 1.14.The microhardness of the two substrates was 190HV0.2 and 220HV0.2. The reciprocal is 1.16, which indicates that the improvement of abrasion resistance of aluminum bronze is the result of increasing the hardness of the material. The wear mechanism of aluminum bronze and Si3N4 balls accords with the characteristics of abrasive wear.