Microstructure And Properties Of YH31 Alloy Cast Iron Used As Piston Rings

The internal combustion engine piston ring works under the harsh condition, and has a strong friction with the cylinder liner, and also suffered from the alternating stress, wear, abrasion and fatigue fracture failure were often occured, which have a direct impact on fuel consumption of the internal combustion engine, working stability and the horsepower. Alloy cast iron has good heat resistance, wear resistance, corrosion resistance and low-temperature resistance and other physical-chemical properties, and it is a good material for the manufacture of internal combustion piston rings.In order to improve the performance of piston rings, based on changing the components of original cast iron and choosing the alloy elements preferably, in this research, the piston ring heat treatment process was optimized by adjusting the austenitizing temperature, quenching method, tempering temperature and other parameters. By optical microscopic observation, hardness test, abrasion resistance test and corrosion resistance test methods, the effects of different heat treatment process on the microstructure, hardness, wear resistance of cast iron piston rings alloy were studied and finally the best heat treatment process was chosen.Considering the microstructure, the overall performance microstructure, mechanical properties, wear resistance and corrosion resistance of YH31 alloy cast iron piston ring, the heat treatment process of the quenching at 1000 ℃ and medium tempering temperature(480 ℃× 2 h) was the better heat treatment method. The results showed that: the hardness of YH31 alloy cast iron piston rings was the most significantly increased by the above process, reaching 438 HV, and the wear resistance was the best among five samples, the wear rate of which was only 0.11 mg / min. The corrosion resistance tests were performed in oxidizing solution(15mol / L H2SO4), alkaline solution(5mol / L NaOH), saline solution(0.2mol / L FeCl3), reducing solution(3mol / L HCl), respectively, and oxidation-reducing solution(1mol / L HCl + 1mol / L HNO3 mixed acid) and it was found that the weight loss of the iron alloy quenched at 1000 ℃ and tempered at 480 ℃ corrosion in the solution was the least and showed the best corrosion resistance.