阅读说明：本技术 一种高强度高延伸率铸态球墨铸铁 (High-strength high-elongation as-cast nodular cast iron ) 是由 焦金国 焦洪雷 焦洪开 于 2020-10-30 设计创作，主要内容包括：本发明涉及一种高强度高延伸率铸态球墨铸铁,化学成分的质量百分数为：C含量3.7％-3.8％、Si含量2.4％-2.6％、Mn含量0.3％-0.4％、Mg含量0.01%-0.05%、Cu含量0.15%-0.3%、Cr含量0.09％-0.14％、Sn含量0.02％-0.025％、Mo含量0.04％-0.06％、铸元素变质剂0.03％-0.035％、P含量≤0.07%、S含量≤0.03%、剩余为铁元素及不可避杂质。本发明利用合金元素调控基体组织、提高球墨铸铁件的综合力学能力,使其同时具有较高强度和高的延伸率。(The invention relates to high-strength high-elongation as-cast nodular cast iron which comprises the following chemical components in percentage by mass: 3.7 to 3.8 percent of C, 2.4 to 2.6 percent of Si, 0.3 to 0.4 percent of Mn, 0.01 to 0.05 percent of Mg, 0.15 to 0.3 percent of Cu, 0.09 to 0.14 percent of Cr, 0.02 to 0.025 percent of Sn, 0.04 to 0.06 percent of Mo, 0.03 to 0.035 percent of casting element modifier, less than or equal to 0.07 percent of P, less than or equal to 0.03 percent of S, and the balance of iron and inevitable impurities. The invention utilizes alloy elements to regulate and control the matrix structure and improve the comprehensive mechanical capability of the nodular iron casting, so that the nodular iron casting has higher strength and high elongation.)

1. The high-strength high-elongation as-cast nodular cast iron is characterized by comprising the following chemical components in percentage by mass: 3.7 to 3.8 percent of C, 2.4 to 2.6 percent of Si, 0.3 to 0.4 percent of Mn, 0.01 to 0.05 percent of Mg, 0.15 to 0.3 percent of Cu, 0.09 to 0.14 percent of Cr, 0.02 to 0.025 percent of Sn, 0.04 to 0.06 percent of Mo, 0.03 to 0.035 percent of casting element modifier, less than or equal to 0.07 percent of P, less than or equal to 0.03 percent of S, and the balance of iron and inevitable impurities.

2. The as-cast spheroidal graphite cast iron according to claim 1, wherein: the mass percentage of the chemical components is as follows: 3.71% of C, 2.45% of Si, 0.32% of Mn, 0.02% of Mg, 0.2% of Cu, 0.1% of Cr, 0.021% of Sn, 0.05% of Mo, 0.031% of cast element modifier, 0.07% of P, 0.03% of S, and the balance of iron and inevitable impurities.

3. The as-cast spheroidal graphite cast iron according to claim 1, wherein: the tensile strength of the as-cast nodular cast iron is more than or equal to 600 MPa, the yield strength is more than or equal to 370 MPa, the elongation is more than or equal to 10 percent, and the Brinell hardness is 190-250 HBW.

4. The as-cast spheroidal graphite cast iron according to claim 1, wherein: the casting element alterant mainly comprises the following components: cerium element Ce for strongly promoting spheroidization and a metal compound fluxing agent, wherein the metal compound fluxing agent is an Sn compound.

Technical Field

The invention belongs to the technical field of casting, and particularly relates to high-strength high-elongation as-cast nodular cast iron.

Background

The cast iron is an iron-carbon alloy with a carbon content of more than 2.11 percent, which is obtained by high-temperature melting and casting and molding of iron and steel such as industrial pig iron, scrap steel and other alloy materials thereof, besides Fe, carbon in other cast iron is precipitated in a graphite form, if the precipitated graphite is strip-shaped, the cast iron is grey cast iron or grey cast iron, if the precipitated graphite is vermicular, the cast iron is malleable cast iron, or nodular cast iron, and if the precipitated graphite is nodular, the cast iron is nodular cast iron. The nodular iron castings have good mechanical properties and casting properties, so that the nodular iron castings become a choice for replacing cast steel blank forming materials, and with the rapid development of economy and the improvement of technological level, the no-load and light-weight requirements of automobile products are continuously strengthened, and the requirements of automobile parts on high-strength and high-toughness nodular iron castings are further promoted.

Disclosure of Invention

The invention aims to provide high-strength high-elongation as-cast nodular cast iron, which is expected to regulate and control matrix structure by using alloy elements and improve the comprehensive mechanical capacity of a nodular cast iron part, so that the nodular cast iron has high strength and high elongation.

In order to solve the technical problems, the invention adopts the following technical scheme: the high-strength high-elongation as-cast nodular cast iron is characterized by comprising the following chemical components in percentage by mass: 3.7 to 3.8 percent of C, 2.4 to 2.6 percent of Si, 0.3 to 0.4 percent of Mn, 0.01 to 0.05 percent of Mg, 0.15 to 0.3 percent of Cu, 0.09 to 0.14 percent of Cr, 0.02 to 0.025 percent of Sn, 0.04 to 0.06 percent of Mo, 0.03 to 0.035 percent of casting element modifier, less than or equal to 0.07 percent of P, less than or equal to 0.03 percent of S, and the balance of iron and inevitable impurities.

The high-strength high-elongation as-cast nodular cast iron is characterized in that: the mass percentage of the chemical components is as follows: 3.71% of C, 2.45% of Si, 0.32% of Mn, 0.02% of Mg, 0.2% of Cu, 0.1% of Cr, 0.021% of Sn, 0.05% of Mo, 0.031% of cast element modifier, 0.07% of P, 0.03% of S, and the balance of iron and inevitable impurities.

The tensile strength of the as-cast nodular cast iron is more than or equal to 600 MPa, the yield strength is more than or equal to 370 MPa, the elongation is more than or equal to 10 percent, and the Brinell hardness is 190-250 HBW.

The casting element alterant mainly comprises the following components: cerium element Ce for strongly promoting spheroidization and a metal compound fluxing agent, wherein the metal compound fluxing agent is an Sn compound.

A preparation method of high-strength high-elongation as-cast nodular cast iron comprises the following steps: the material is selected, carbon steel scrap, ductile iron scrap and ductile cast iron are selected as raw materials, and a carburant is selected.

Smelting, namely adding the raw materials into an induction furnace for smelting, standing after smelting to 1600 ℃, and then slagging off to obtain molten iron.

And (2) spheroidizing inoculation, namely adding a FeSiMg8Re2 spheroidizing agent, ferrosilicon and a silicon barium inoculant into a spheroidizing bag layer by layer, covering perlite on the spheroidizing bag, flushing molten iron into the spheroidizing bag for spheroidizing, slagging and deslagging after the spheroidizing is finished, and then performing ladle-to-ladle inoculation to obtain pure molten iron.

And (3) molding, namely adding the prepared precoated sand into a molding machine to manufacture a shell mold to form a casting mold shell, putting an iron mold into the casting mold shell, then hoisting the spheroidized pure iron liquid to the casting position of the iron mold for casting, and forming a finished product after casting.

And cooling, namely cooling the finished product, and taking down the molding die through a box removing operation to obtain the as-cast nodular cast iron.

And (3) performing sampling analysis when the temperature is close to 1500 ℃ in the smelting, adjusting ingredients according to an analysis result, and standing for 3-5 minutes.

And red copper scraps are also added into the spheroidizing ladle in the spheroidizing inoculation, and a SiBa compound inoculant is added along with the iron liquid in the ladle-to-ladle inoculation process, and a covering agent is added after the iron liquid is fully stirred.

C is the most basic and important element in cast iron, the graphite separated out usually increases when the carbon content is high, wherein the C content is favorable for graphitization and promotes Mg absorption, and the graphite of the nodular cast iron is spherical.

Si belongs to elements for promoting graphitization, and the improvement of the Si content is beneficial to improving the activity of C

And the dissolution of the silicon carbide in molten iron is reduced, thereby promoting graphitization, and when Si is dissolved in a matrix structure, the silicon carbide can also play a role in solid solution strengthening of ferrite.

P is also a common harmful impurity element in the nodular cast iron, but can reduce the eutectic transformation temperature of the nodular cast iron to a certain extent and narrow the critical humidity range, thereby improving the wear resistance of the nodular cast iron; however, the content of P needs to be strictly controlled because eutectic P has a low melting point, is usually in a liquid state, and is solidified at the eutectic cell boundary, and the mechanical properties of the nodular cast iron are reduced if the content of P is not strictly controlled.

The invention utilizes alloy elements such as Mn, Cu and the like to regulate and control the matrix structure, improves the roundness of graphite, carries out level refinement and stabilizes pearlite, improves the comprehensive mechanical capability of the nodular iron casting, and simultaneously has higher strength and high elongation.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

The high-strength high-elongation as-cast nodular cast iron comprises the following chemical components in percentage by mass: 3.7% of C, 2.4% of Si, 0.3% of Mn, 0.01% of Mg, 0.15% of Cu, 0.09% of Cr, 0.02% of Sn, 0.04% of Mo, 0.03% of cast element modifier, 0.05% of P, 0.02% of S, and the balance of Fe and unavoidable impurities.

Example 2

The high-strength high-elongation as-cast nodular cast iron comprises the following chemical components in percentage by mass: 3.8% of C, 2.6% of Si, 0.4% of Mn, 0.05% of Mg, 0.3% of Cu, 0.14% of Cr, 0.025% of Sn, 0.06% of Mo, 0.035% of cast element modifier, 0.07% of P, 0.03% of S, and the balance of Fe and unavoidable impurities.

S belongs to an anti-graphitization element in nodular cast iron, but the excessive content of P can reduce the fluidity of molten iron and increase the cracking tendency of a casting, so that the content is strictly controlled.

Cu is a medium graphitization promoting element, Cu and iron liquid are mutually soluble to form a liquid solid solution, the combination of carbon and iron can be reduced, the effect of strongly promoting pearlite formation is achieved, the eutectoid transformation temperature is reduced, the pearlite transformation area is enlarged, the pearlite formation is promoted and refined, after the Cu and Mn are combined, the mutual promotion is achieved, austenite is stabilized, the roundness of graphite can be improved, the bead intersection is refined and stabilized, Mn can react with sulfur, and the residual sulfur in the molten metal can be effectively reduced.

In this embodiment, according to the specification of the dimensions of a tensile sample of a ductile iron casting in GB/T1348-2009, a product is detected, a spectrum analyzer is used to analyze the main chemical components of the metallographic sample, and a type optical microscope and a scanning electron microscope are used to observe the graphite morphology, the matrix structure morphology, the lamellar spacing of pearlite, the primary austenite morphology, and the like, wherein the spheroidization grade is 1-2 grade, the spherical diameter is 5-7 grade, and the pearlite content is 50-65%. In conclusion, by adding special casting element alterant and trace elements, the material properties of the cast condition that the tensile strength is more than or equal to 860 and the elongation is more than or equal to 6 percent are realized, and the casting product with high strength, high toughness and uniform internal structure is obtained.

The above embodiments are only specific examples of the present invention, which is not intended to limit the present invention in any way, and any person skilled in the art may modify or modify the technical details disclosed above and equally vary from the equivalent embodiments. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention should fall within the scope of protection of the present invention without departing from the technical principle of the present invention.