High-strength and high-toughness thick-wall nodular cast iron material and casting method thereof

Abstract

The invention provides a high-strength and high-toughness thick-wall nodular cast iron material and a casting method thereof. Raw iron liquid of the material comprises, by mass, 3.5%-3.8% of C, 0.3%-0.60% of Si, smaller than 0.4% of Mn, smaller than 0.06% of P, smaller than 0.05% of S, 0.4%-0.7% of Cr and the balance Fe and inevitable impurities. The casting material subjected to spheroidizing inoculation comprises the following chemical components in percentage by mass: 3.5%-3.8% of C, 1.6%-2.2% of Si, less than 0.4% of Mn, less than 0.06% of P, less than 0.05% of S, 0.4%-0.7% of Cr, 0.5%-0.8% of Cu, 0.04%-0.06% of Mg and 0.01%-0.04% of RE. The casting method comprises the following steps of melting raw materials into molten iron, preparing a nodulizing agent, a nucleating agent, a deslagging agent and Cu in a casting ladle, then discharging, treating the molten iron by adopting a pouring method and a flow following mode, casting after slagging off, and finally carrying out normalizing and tempering heat treatment to obtain the high-strength and high-toughness thick-wall nodular cast iron material, wherein the wall thickness of the material is greater than 100mm, the tensile strength is greater than or equal to 1000MPA, the elongation is greater than or equal to 4%, and the HBW is greater than or equal to 300.

Description

technical field [0001] The invention belongs to the technical field of cast iron materials, and in particular relates to a high-strength toughness thick-walled ductile iron material and a casting method thereof. Background technique [0002] Ductile iron has high tensile strength and bending fatigue limit, and also has quite good plasticity and toughness. It is often used in the production of parts with complex stress, high strength, toughness, wear resistance, etc., such as automobiles, tractors, and internal combustion engines. Other crankshafts, camshafts, and medium-pressure valves for general machinery. [0003] QT1000-4 has high tensile strength and high yield strength, with a hardness of 280-320HB. It is widely used in high-end equipment such as mining machinery gears, special equipment swing arms, and low-speed diesel engine crankshafts. At present, the strength and toughness of general QT1000-4 materials are difficult to meet the technical requirements in the state...

AI Technical Summary

Problems solved by technology

At present, the strength and toughness of general QT1000-4 materials are difficult to meet the technical requirements in the state of thick wall (wall thickness greater than 100mm). The production process needs to strictly control other trace elements (such as V, Ti). In the production process of cast iron, it is mainly to prevent nodularization decline and graphite floating. Ti element can inhibit nodularization, especially in the production of thick-walled high-strength ductile cast iron, so the raw materials must be selected to control the residual amount of Ti; adding Ni , Mo and other alloying elements to increase the pearlite content and increase the tensile strength, because Ni and Mo alloys are expensive, the production cost is high, and the process is complicated

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