High-silicon-molybdenum ductile iron material and preparation method thereof

Abstract

The invention discloses a high-silicon-molybdenum ductile iron material and a preparation method thereof. The high-silicon-molybdenum ductile iron material comprises the following components in percentage by weight: 2.90 to 3.35 percent of C, 4.40 to 4.80 percent of Si, 0.50 to 0.75 percent of Mo, 0.30 to 0.50 percentage of Cr, 0.20 to 0.45 percent of V, 0.10 to 0.30 percent of Mn, 0.04 to 0.07 percent of Mg, less than or equal to 0.07 percent of P, less than or equal to 0.02 percent of S, and the balance of Fe. For the high-silicon-molybdenum ductile iron material, the tensile strength is more than or equal to 710 MPa, the yield strength is more than or equal to 500 MPa, the extensibility is more than or equal to 10 percent, and the hardness is 230 to 265 HBW5/750. The high-silicon-molybdenum ductile iron material also contains a trace amount of Sn and Sb. The high-silicon-molybdenum ductile iron material eliminates fragmental graphite and graphite deterioration layers, ensures the spheroidization grades of the parts with different wall thicknesses, and the defects of microscopic shrinkage and the like are overcome.

Description

technical field [0001] The invention relates to a ductile iron material and a preparation method thereof, in particular to a high-silicon-molybdenum nodular iron material used for high-temperature-resistant parts of automobiles and a preparation method thereof. Background technique [0002] High-silicon-molybdenum ductile iron is widely used in automotive high-temperature resistant parts such as exhaust pipes and turbine shells due to its high high-temperature strength, thermal fatigue resistance, excellent oxidation resistance, growth and good high-temperature creep resistance. . With the improvement of people's awareness of environmental protection and regulations, HT250 and even vermicular iron materials can no longer meet the performance requirements of engine emissions, while the performance of high-silicon-molybdenum ductile iron can meet the current American standards and Euro IV standards. It is foreseeable that high-silicon Molybdenum ductile iron, as an emerging h...

AI Technical Summary

Problems solved by technology

[0003] However, the biggest problem currently existing in high-silicon-molybdenum ductile iron is that due to the high content of silicon and molybdenum, it is brittle, prone to produce fragmented graphite and graphite deterioration layers, and prone to micro-shrinkage, which leads to metallographic Organizations Difficult to Meet

However, the addition of vanadium and chromium is easy to form carbides, making it more brittle and more likely to produce fragmented graphite and microscopic shrinkage.

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