Material of niobium alloy cast iron piston ring and its production process, the material for the piston ring includes: 3.4 -- 3.75% carbon, 2.1 -- 2.4% silicon, 0.5 -- 0.9% manganese, 0.35 -- 0.5% phosphorus, ≤0.1 sulfur, 0.2 -- 0.3% chromium, 0.2 -- 0.3% molybdenum, 0.2 -- 0.3% copper, 0.2 -- 0.3% niobium, and 91.2 -- 92% iron. Use power frequency furnace melting.
The invention is suitable for piston ring materials of various diesel engines and gasoline engines, especially for high-horse power diesel engines. Its service life is alloy cast iron piston ring three times, or even longer. Stable performance, convenient processing.
At present, the alloy cast iron piston ring used in diesel engine is chromium, molybdenum, copper alloy cast iron. Its stability is not good, short service life. Usually, there is only one frame repair period. That is, 180,000 to 200,000 locomotives can travel kilometers. That's 4,300 to 4,800 hours.
The purpose of the invention is to provide a piston ring material with stable performance, wear resistance and long service life and its production process.
The invention relates to adding niobium alloy directly prepared by electric furnace aluminum reduction method with niobium iron concentrate into the original alloy cast iron. The graphite in the original alloy cast iron tends to be refined and evenly distributed (contrast in FIG. 1 and 2), the eutectic mass becomes smaller (contrast in FIG. 3 and 4), and the ferrite becomes smaller. At the same time, more than 100 pieces /mm2 are uniformly precipitated in the pearlite. Polygonal triaxial dendrite niobium carbon itride with particle size of 3 ~ 7μm (FIG. 5) has a hardness of up to HV2000 ~ 2500. And firmly combined with the matrix, friction is not easy to fall off. Due to the formation of niobium carbonitride, the boundary of eutectic clusters is purified, and the binding force between eutectic clusters is improved, so the tensile strength, bending strength, elasticity and thermal stability are improved. The comprehensive properties of alloy cast iron are obviously improved by the change of full phase microstructure. Especially outstanding is improved wear resistance.
