Low-carbon equivalent high strength and toughness cast steel and preparation method thereof

Abstract

The invention relates to a low-carbon equivalent high strength and toughness cast steel and a preparation method thereof. The low-carbon equivalent high strength and toughness cast steel comprises the following chemical components in percentage by weight: 0.14 to 0.18% of C, 0.30 to 0.60% of Si, 1.00 to 1.20% of Mn, 0.40 to 0.60% of Cr, 0.70% to 0.80% of Ni, 0.20 to 0.30% of Mo, not greater than 0.025% of P, not greater than 0.020% of S, 0.02 to 0.03% of V, 0.03 to 0.05% of Nb, not greater than 0.20% of Cu, and the balance of Fe. The preparation method is characterized by comprising the following steps: performing secondary refining through an electric-arc furnace and an AOD (Argon Oxygen Decarburization) furnace; and carrying out high-heat treatment. The low-carbon equivalent high strength and toughness cast steel and the preparation method thereof have the beneficial effects that the micro-alloying technology is introduced to the production of low-carbon cast steel, so that the strength as well as low-temperature toughness of the material can be greatly improved on the premise that high welding performance is remained; the electric-arc furnace and the AOD furnace are adopted for performing joint smelting; the decarburization quantity in the oxidization period can be improved, and phosphorus and other harmful elements in molten steel can be removed by the electric-arc furnace; the secondary deoxidation is performed by the AOD furnace, the argon is charged for refining, and thus oxide inclusion in the molten steel, and N, H, O and other gases can be removed as far as possible, and as a result, the cleanness of the molten steel can be greatly improved; and before hardening and tempering, the high-temperature pretreatment process is carried out, thus the crystal grain is refined, and a condition is created for finish heat treatment.

Description

technical field [0001] The invention belongs to the technical field of low-alloy steel material casting, and in particular relates to a low-carbon equivalent high-strength toughness cast steel and a preparation method thereof. Background technique [0002] Due to the harsh operating environment of the mine truck, poor working road conditions, low ambient temperature, long working hours, and large impact loads during work, its key components - supporting shafts and other castings are required to have high yield strength (not less than 585Mpa) and tensile strength (not less than 725Mpa), good plasticity (elongation not less than 20%) and toughness (impact at -40°C not less than 27J), and good weldability (carbon equivalent Cev≤0.60%) . [0003] The chemical composition and mechanical properties of 4B in the American standard ASTM A487 "Standard Specification for Steel Castings Suitable for Pressure Service" are as follows: [0004] [0005] When the ASTMA4874B material me...

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Problems solved by technology

[0006] The technical problem to be solved by the present invention is to provide a k

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