Aluminum alloy die casting mold material and method for manufacturing the same

Abstract

The application discloses an aluminum alloy die casting die material, and raw material components include 3.6-3.9% C, 2.1-2.7% Si, <=0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, <=0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, <=0.02% S, 0.3-0.8% Cu, and the rest is Fe and inevitable impurities. The application also discloses a preparation method of the aluminum alloy die casting die material, which comprises the following steps: configuring and weighing raw materials, melting, ladle inoculation and modification treatment, annealing treatment of continuous casting profile, homogenizing annealing treatment, profile processing into an aluminum alloy die casting die, heat treatment quenching and tempering treatment, and the aluminum alloy die casting die with excellent aluminum liquid corrosion resistance is obtained, the surface quality of the formed aluminum alloy die casting is improved, and the service life of the die is significantly prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of die casting equipment manufacturing, and particularly relates to an aluminum alloy die casting die material and a preparation method thereof. BACKGROUND

[0002] In the forming process of aluminum alloy die castings, the die not only has to withstand strong friction caused by rapid filling of high-temperature aluminum alloy melt, but also has to withstand strong pressure exerted on the die by high-pressure aluminum alloy casting, and in addition, the die has to withstand strong corrosion caused by interdiffusion and formation of intermetallic compounds between the high-temperature aluminum alloy melt and the die material. The above-mentioned many unfavorable factors affect the normal service life of the existing die steel. Therefore, in order to obtain high-surface-quality castings and prolong the service life of aluminum alloy dies, the aluminum alloy die casting die material not only needs to have high strength, high hardness, good wear resistance and other mechanical properties at high temperatures, but also needs to have excellent aluminum liquid corrosion resistance.

[0003] The existing aluminum alloy die casting die materials generally use hot work die steels, such as 4Cr5MoV. These materials have excellent high-temperature mechanical properties, wear resistance and high hardness, and fully meet the requirements of mechanical properties, hardness and wear resistance of aluminum alloy die casting dies working at high temperatures. However, because the base Fe of the die steel and Al easily interdiffuse and form various intermetallic compounds at high temperatures, the existing steel dies have poor aluminum melt corrosion resistance, which causes problems such as die surface cracking, formation of pitting, surface aluminum sticking and the like, and seriously affects the surface quality of the aluminum alloy die castings. Therefore, improving the aluminum liquid corrosion resistance of the material has important engineering significance for improving the service life of the aluminum alloy die casting die and the surface quality of the aluminum alloy die casting, and further promoting the progress of lightweight technology.

[0004] Traditional cast iron has been the first choice for manufacturing electrolytic aluminum liquid suction pipes, aluminum alloy low-pressure casting riser tubes and aluminum alloy smelting crucibles because it contains graphite that is not wetted by aluminum liquid and has good thermal conductivity and excellent economy. However, the traditional cast iron cast by sand casting has coarse and unevenly distributed graphite and unavoidable various casting defects (shrinkage holes, shrinkage porosity, gas holes, slag inclusions and inclusions, etc.), which result in poor mechanical properties such as strength, fatigue performance, consistency of performance of different batches of castings, high-temperature mechanical properties and high-temperature wear resistance of the traditional castings, and cannot meet the requirements of service performance of the die casting die. Therefore, it is necessary to upgrade the traditional cast iron material by adding thermal strength elements (such as chromium Cr, molybdenum Mo and vanadium V) to improve the room temperature and high-temperature mechanical properties of the cast iron material, so as to be used for manufacturing aluminum alloy die casting dies. SUMMARY

[0005] The application aims to provide an aluminum alloy die casting die material to solve the poor surface performance of existing hot work die steel caused by aluminum liquid corrosion.

[0006] The application also aims to provide a preparation method of the aluminum alloy die casting die material.

[0007] The application adopts a technical scheme, i.e., the aluminum alloy die casting die material, raw material components and mass percentages include: 3.6-3.9% C, 2.1-2.7% Si, ≤0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.3-0.8% Cu, and the rest is Fe and inevitable impurities.

[0008] The application also has the characteristics that,

[0009] The morphological structure of the aluminum alloy die casting die material includes sorbite + vermicular graphite + spherical graphite, the carbide in the sorbite is an alloy carbide of Fe, Cr, Mo and V, the vermicular graphite accounts for more than 80% of the total volume of the graphite, and the size and spatial distribution of the vermicular graphite are uniform.

[0010] The length of the vermicular graphite is 10-25 um.

[0011] The diameter of the spherical graphite is 20-30 um.

[0012] The application also adopts another technical scheme, i.e., a preparation method of the aluminum alloy die casting die material, which is used to prepare the above-mentioned aluminum alloy die casting die material, and is implemented according to the following steps:

[0013] Step 1, configuration and weighing of raw materials, and melting;

[0014] Step 2, inoculation and modification treatment of molten iron;

[0015] Step 3, annealing treatment of the continuously cast profile immediately;

[0016] Step 4, homogenization annealing treatment of the profile after annealing in step 3;

[0017] Step 5, processing the profile after homogenization annealing treatment into an aluminum alloy die casting die, and then performing heat treatment quenching and tempering treatment on the die, so as to obtain the aluminum alloy die casting die with excellent aluminum liquid corrosion resistance.

[0018] The application also has the characteristics that,

[0019] Step 1 is implemented according to the following steps:

[0020] Step 1.1, scrap steel, blast furnace molten iron or pig iron, ferrosilicon, ferromanganese, ferromolybdenum, ferrovanadium, red copper, phosphorus iron, inoculant, modifier, are configured and weighed according to the mass percentage of raw material components: 3.6-3.9% C, 2.1-2.7% Si, ≤0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.3-0.8% Cu, the rest is Fe and inevitable impurities;

[0021] Step 1.2, the scrap steel, blast furnace molten iron or pig iron, ferrosilicon configured and weighed in step 1.1 are heated to 1550℃ in a medium-frequency melting furnace to melt into molten iron, and then ferromanganese, ferrochrome, ferromolybdenum, ferrovanadium, red copper, phosphorus iron are sequentially added to the molten iron in the medium-frequency furnace.

[0022] Step 2 is implemented according to the following steps:

[0023] Step 2.1, according to the process requirements of horizontal continuous casting, the molten iron melted in the medium-frequency furnace in step 1.2 is poured into a ladle containing inoculant and modifier, the molten iron is inoculated and modified once, then the molten iron in the ladle is poured into a crystallizer for horizontal continuous casting of the profile;

[0024] The inoculant used for inoculation treatment has the following components: 62-72% Si, 4-6% Ba, 2-3% Ca, 2-3% Mn, the rest is Fe and inevitable impurities. The inoculant used for primary inoculation is granular, the particle size is 0.5-1mm, the addition amount of the inoculant for primary inoculation is 0.4% of the total amount of molten iron; the modifier used for primary modification is granular, the particle size is 0.5-2mm, the amount used is 0.8% of the total amount of molten iron.

[0025] Step 2.2, during the horizontal continuous casting of the profile, the stepping operation of the continuous casting profile is: stopping cooling for 0.5-3min every 50mm of drawing, and synchronously supplementing the modifier above the crystallizer;

[0026] Secondary collaborative inoculation adopts wire feeding inoculation, the addition amount of the inoculant is 0.2% of the total amount of molten iron. The modifier used for modification has the following components: 4.5-5.5% Mg, 7-8% Ti, 0.35-0.5% Ce, 4.0-4.5% Ca, 1.0-1.5% Al, 48-52% Si, the rest is iron and inevitable impurities, secondary collaborative modification adopts wire feeding, the amount of modifier used is 0.4% of the total amount of molten iron.

[0027] Step 3 is implemented according to the following steps: the annealing temperature is 550-600℃, the annealing holding time is 5-8h, after the annealing holding is completed, it is first cooled to 200℃ with the furnace, and then air cooled to room temperature after discharging.

[0028] Step 4 is specifically implemented according to the following steps: the homogenizing annealing process is 1050 DEG C for 12-15h, furnace cooling to 500 DEG C, and then air cooling to room temperature.

[0029] Step 5 is specifically implemented according to the following steps: the quenching heating temperature is 900-920 DEG C, the quenching heating holding time is 1-2h, after the quenching heating holding time ends, the mold is rapidly quenched into quenching medium No. 20 machine oil or diesel oil or spindle oil; after cooling in the oil for 5-10s, the temperature of the mold is cooled to 200 DEG C, and then the mold is placed in a heating furnace for tempering; the tempering temperature is 530 DEG C-550 DEG C, the tempering holding time is 3-4h, and after the tempering holding time ends, the mold is taken out of the furnace and air cooled to room temperature; after tempering, the microstructure is sorbite + vermicular graphite + spherical graphite, and the hardness is not less than 45HRC.

[0030] The aluminium alloy die casting die material prepared by the application has high strength, high hardness, high wear resistance, high thermal fatigue performance, and high corrosion resistance to aluminium liquid, and the profile has good mechanical properties, thermal fatigue performance, high hardness, high wear resistance, and excellent corrosion resistance to aluminium liquid, so that the service life of the aluminium alloy die casting die made of the material is higher than that of the existing hot work die steel, and the application has great significance for the technical progress of the aluminium alloy die casting die manufacturing technology and the vehicle lightweight technology. DETAILED DESCRIPTION

[0031] The application will be described in detail below in combination with specific embodiments.

[0032] The aluminium alloy die casting die material has the following raw material components by mass percentage: 3.6-3.9% C, 2.1-2.7% Si, ≤0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.3-0.8% Cu, and the rest is Fe and inevitable impurities.

[0033] The morphological structure of the aluminium alloy die casting die material includes sorbite, vermicular graphite, and spherical graphite. The carbide in the sorbite is an alloy carbide of (Fe, Cr, Mo, V), the vermicular graphite accounts for more than 80% of the total volume of the graphite, and the size and spatial distribution of the vermicular graphite are uniform.

[0034] The length of the vermicular graphite is 10-25um.

[0035] The diameter of the spherical graphite is 20-30um.

[0036] The application discloses a preparation method of an aluminum alloy die casting die material, and specifically comprises the following steps:

[0037] Step 1, the raw materials are configured and weighed, and melted, and the specific implementation is as follows:

[0038] Step 1.1, the scrap steel, the blast furnace molten iron or pig iron, the silicon iron, the manganese iron, the molybdenum iron, the vanadium iron, the red copper, the phosphorus iron, the inoculant and the vermiculite are configured and weighed according to the mass percentage of the raw material components: 3.6-3.9% C, 2.1-2.7% Si, ≤0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.3-0.8% Cu, and the rest is Fe and inevitable impurities;

[0039] Step 1.2, the scrap steel, the blast furnace molten iron or pig iron and the silicon iron configured and weighed in step 1.1 are heated to 1550 DEG C in a medium-frequency melting furnace to be molten into molten iron, then the manganese iron, the chromium iron, the molybdenum iron, the vanadium iron, the red copper and the phosphorus iron are sequentially added into the molten iron in the medium-frequency furnace;

[0040] Step 2, inoculation and modification treatment of the molten iron;

[0041] Step 2.1, according to the process requirement of horizontal continuous casting, the molten iron in the medium-frequency furnace in step 1.2 is poured into a ladle containing inoculants and modifiers, the molten iron is subjected to primary inoculation and modification treatment, then the molten iron in the ladle is poured into a crystallizer to be horizontally continuously cast into a profile;

[0042] The inoculant used in the inoculation treatment comprises the following components: 62-72% Si, 4-6% Ba, 2-3% Ca, 2-3% Mn, and the rest is Fe and inevitable impurities; the inoculant used in the primary inoculation is in a granular form, the particle size is 0.5-1 mm, the inoculant is added in an amount of 0.4% of the total amount of the molten iron; the modifier used in the primary modification treatment is in a granular form, the particle size is 0.5-2 mm, and the amount is 0.8% of the total amount of the molten iron.

[0043] Step 2.2, in the horizontal continuous casting process of the profile, the step operation of the continuously cast profile is as follows: stopping cooling for 0.5-3 min every time the profile is drawn by 50 mm, synchronously supplementing the modifier above the crystallizer to realize secondary collaborative inoculation and modification treatment of the molten iron, and the obtained profile is dense and free of shrinkage holes, shrinkage porosities, gas holes and inclusions and slag inclusions which exist in the castings produced by conventional casting methods.

[0044] The secondary synergic inoculation is carried out by feeding inoculation, and the inoculation amount is 0.2% of the total molten iron. The modifier used in the modification treatment is composed of 4.5-5.5% Mg, 7-8% Ti, 0.35-0.5% Ce, 4.0-4.5% Ca, 1.0-1.5% Al, and 48-52% Si, and the rest is iron and inevitable impurities. The secondary synergic modification treatment is carried out by feeding, and the modifier amount is 0.4% of the total molten iron.

[0045] The microstructure of the profile obtained in step 2 is: metal matrix (martensite + residual austenite) + vermicular graphite + spherical graphite, wherein the vermicular graphite accounts for more than 80% of the total volume of the graphite, and the size and spatial distribution of the vermicular graphite are uniform.

[0046] Step 3, immediately annealing the profile after continuous casting;

[0047] The annealing temperature is 550-600℃, the annealing holding time is 5-8h, and after the annealing holding is finished, the profile is first cooled to 200℃ in the furnace, and then air-cooled to room temperature after being taken out of the furnace.

[0048] Step 4, homogenizing annealing the profile after annealing in step 3;

[0049] The homogenizing annealing process is: 1050℃ for 12-15h, and then air-cooled to room temperature after being taken out of the furnace after cooling to 500℃ in the furnace.

[0050] Step 5, processing the profile after homogenizing annealing into an aluminum alloy die casting mold, and then performing heat treatment quenching and tempering on the mold, so as to obtain an aluminum alloy die casting mold with excellent corrosion resistance to aluminum liquid.

[0051] The quenching heating temperature is 900-920℃, the quenching heating holding time is 1-2h, after the quenching heating holding is finished, the mold is rapidly quenched into quenching medium No. 20 machine oil or diesel oil or spindle oil; after being cooled in the oil for 5-10 seconds, the temperature of the mold is cooled to 200℃, and then the mold is put into a heating furnace for tempering; the tempering temperature is 530-550℃, the tempering holding time is 3-4h, and after the tempering holding is finished, the mold is air-cooled to room temperature, and the microstructure obtained after tempering is: sorbite + vermicular graphite + spherical graphite, and the hardness is not less than 45HRC.

[0052] Example 1

[0053] The preparation method of the aluminum alloy die casting mold material is implemented according to the following steps:

[0054] Step 1, weighing and melting the raw materials according to the configuration;

[0055] Step 1.1, configure and weigh scrap steel, blast furnace molten iron or pig iron, ferrosilicon, ferromanganese, ferromolybdenum, ferrovanadium, red copper, phosphorus iron, inoculant, vermiculite according to the mass percentage of raw material components: 3.7% C, 2.1% Si, ≤0.4% Mn, 0.5% Cr, 1.5% Mo, 0.5% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.5% Cu, the rest is Fe and inevitable impurities;

[0056] Step 1.2, heat the scrap steel, blast furnace molten iron or pig iron, ferrosilicon configured and weighed in step 1.1 to 1550℃ in a medium frequency melting furnace to melt into molten iron, then add ferromanganese, ferrochrome, ferromolybdenum, ferrovanadium, red copper, phosphorus iron into the molten iron in the medium frequency furnace in turn;

[0057] Step 2, inoculation and modification of molten iron;

[0058] Step 2.1, according to the process requirements of horizontal continuous casting, pour the molten iron melted in the medium frequency furnace in step 1.2 into a ladle containing inoculant and modifier, perform primary inoculation and modification treatment on the molten iron, then pour the molten iron in the ladle into a crystallizer for horizontal continuous casting of the profile;

[0059] The inoculant used for inoculation treatment has the following components: 62-72% Si, 4-6% Ba, 2-3% Ca, 2-3% Mn, the rest is Fe and inevitable impurities. The inoculant used for primary inoculation is granular with a particle size of 0.5-1mm; the addition amount of the inoculant for primary inoculation is 0.4% of the total amount of molten iron; the modifier used for primary modification treatment is granular with a particle size of 0.5-2mm, and the amount used is 0.8% of the total amount of molten iron.

[0060] Step 2.2, during the horizontal continuous casting of the profile, the stepping operation of the continuous casting profile is: stop cooling for 0.5-3min every 50mm of drawing, synchronously supplement the modifier above the crystallizer to realize secondary collaborative inoculation and modification treatment of the molten iron, and obtain the profile which is dense and free of shrinkage holes, shrinkage porosity, gas holes and inclusions and slag inclusions existing in the castings produced by conventional casting methods.

[0061] Secondary collaborative inoculation adopts wire feeding inoculation, and the addition amount of the inoculant is 0.2% of the total amount of molten iron. The modifier used for modification treatment has the following components: 4.5-5.5% Mg, 7-8% Ti, 0.35-0.5% Ce, 4.0-4.5% Ca, 1.0-1.5% Al, 48-52% Si, the rest is iron and inevitable impurities. Secondary collaborative modification treatment adopts wire feeding, and the amount of modifier used is 0.4% of the total amount of molten iron.

[0062] Step 3, annealing treatment is immediately performed on the continuously cast profile;

[0063] The annealing temperature is 550℃, the annealing holding time is 8h, and after the annealing holding is finished, the profile is first cooled to 200℃ in the furnace and then air-cooled to room temperature after being taken out of the furnace.

[0064] Step 4, homogenizing annealing treatment is performed on the profile after the annealing in step 3;

[0065] The homogenizing annealing process is: 1050℃ for 12h, and after the furnace is cooled to 500℃, the profile is taken out of the furnace and air-cooled to room temperature.

[0066] Step 5, the profile after the homogenizing annealing treatment is processed into an aluminum alloy die-casting die, and then the die is subjected to heat treatment quenching and tempering treatment, so that an aluminum alloy die-casting die with excellent corrosion resistance to aluminum liquid is obtained. The profile has the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid die-casting forming temperature.

[0067] The quenching heating temperature is 900℃, the quenching heating holding time is 1.5h, and after the quenching heating holding is finished, the die is rapidly quenched into quenching medium No. 20 machine oil or diesel oil or spindle oil; after being cooled in the oil for 5-10 seconds, the temperature of the die is cooled to 200℃, and then the die is placed into a heating furnace for tempering; the tempering temperature is 530℃, the tempering holding time is 4h, and after the tempering holding is finished, the die is taken out of the furnace and air-cooled to room temperature. The obtained structure after the tempering is: sorbite + vermicular graphite + spherical graphite, and the hardness is not less than 45HRC. The profile has the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid die-casting forming temperature.

[0068] Example 2

[0069] The preparation method of the aluminum alloy die-casting die material according to the present application is specifically implemented according to the following steps:

[0070] Step 1, the raw materials are weighed and melted according to the configuration, and the specific implementation is as follows:

[0071] Step 1.1, the scrap steel, blast furnace molten iron or pig iron, silicon iron, manganese iron, molybdenum iron, vanadium iron, red copper, phosphorus iron, inoculant and vermiculite are configured and weighed according to the raw material component mass percentage: 3.8% C, 2.5% Si, ≤0.4% Mn, 0.7% Cr, 1.5% Mo, 0.5% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.5% Cu, and the rest is Fe and inevitable impurities.

[0072] Step 1.2, the scrap steel, blast furnace molten iron or pig iron, ferrosilicon in step 1.1 is heated to 1550℃ in a medium frequency melting furnace to melt into molten iron, then the ferromanganese, ferrochrome, ferromolybdenum, ferrovanadium, red copper and ferrophosphorus are added into the molten iron in the medium frequency furnace in sequence;

[0073] Step 2, inoculation and modification treatment of the molten iron;

[0074] Step 2.1, according to the process requirements of horizontal continuous casting, the molten iron in step 1.2 is poured into a ladle containing inoculant and modifier for primary inoculation and modification treatment, then the molten iron in the ladle is poured into a crystallizer for horizontal continuous casting of the profile;

[0075] The inoculant used in the inoculation treatment has the following composition: 62-72% Si, 4-6% Ba, 2-3% Ca, 2-3% Mn, and the rest is Fe and unavoidable impurities. The inoculant used in the primary inoculation is granular with a particle size of 0.5-1mm; the addition amount of the inoculant for primary inoculation is 0.4% of the total amount of the molten iron; the modifier used in the primary modification treatment is granular with a particle size of 0.5-2mm, and the amount is 0.8% of the total amount of the molten iron.

[0076] Step 2.2, during the horizontal continuous casting of the profile, the step operation of the continuous casting profile is: stopping cooling for 0.5-3min every 50mm of drawing, synchronously supplementing the modifier above the crystallizer to realize secondary collaborative inoculation and modification treatment of the molten iron, and obtaining the profile which is dense and free of shrinkage holes, shrinkage porosity, gas holes and inclusions and slag inclusions existing in the castings produced by conventional casting methods.

[0077] The secondary collaborative inoculation adopts the wire feeding inoculation method, and the addition amount of the inoculant is 0.2% of the total amount of the molten iron. The modifier used in the modification treatment has the following composition: 4.5-5.5% Mg, 7-8% Ti, 0.35-0.5% Ce, 4.0-4.5% Ca, 1.0-1.5% Al, 48-52% Si, and the rest is Fe and unavoidable impurities. The secondary collaborative modification treatment adopts the wire feeding method, and the amount of the modifier is 0.4% of the total amount of the molten iron.

[0078] Step 3, immediately annealing the continuous casting profile;

[0079] The annealing temperature is 570℃, the annealing holding time is 6h, and after the annealing holding is completed, the furnace is cooled to 200℃ first, and then the profile is taken out of the furnace and air cooled to room temperature.

[0080] Step 4, homogenizing annealing treatment of the profile annealed in step 3;

[0081] The homogenizing annealing process is: 1050℃ for 13h, and then the furnace is cooled to 500℃ and the profile is taken out of the furnace and air cooled to room temperature.

[0082] Step 5, the aluminum alloy die casting mold is processed from the homogenization annealing processed profile, and then the mold is subjected to heat treatment quenching and tempering treatment, so that the aluminum alloy die casting mold with excellent corrosion resistance to aluminum liquid is obtained. The profile has the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid die casting forming temperature.

[0083] The heat treatment quenching heating temperature is 920℃, the quenching heating holding time is 2h, after the quenching heating holding is finished, the mold is rapidly quenched into quenching medium No. 20 machine oil or diesel oil or spindle oil; after the mold is cooled in the oil for 5-10 seconds, the temperature of the mold is cooled to 200℃, then the mold is put into a heating furnace for tempering; the tempering temperature is 540℃, the tempering holding time is 3.5h, after the tempering holding is finished, the mold is taken out of the furnace and air cooled to room temperature, and the obtained structure after the tempering is: sorbite + vermicular graphite + spherical graphite, and the hardness is not less than 45HRC. The profile has the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid die casting forming temperature.

[0084] Example 3

[0085] The preparation method of the aluminum alloy die casting mold material is specifically implemented according to the following steps:

[0086] Step 1, the raw materials are weighed according to the configuration, and are melted, and the specific implementation is as follows:

[0087] Step 1.1, the scrap steel, the blast furnace molten iron or pig iron, the silicon iron, the manganese iron, the molybdenum iron, the vanadium iron, the red copper, the phosphorus iron, the inoculant and the vermicularizing agent are configured and weighed according to the raw material component mass percentage: 3.9% C, 2.7% Si, ≤0.4% Mn, 0.5% Cr, 2.0% Mo, 0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.8% Cu, and the rest is Fe and inevitable impurities;

[0088] Step 1.2, the scrap steel, the blast furnace molten iron or pig iron, the silicon iron configured and weighed in step 1.1 are heated to 1550℃ in a medium frequency melting furnace to be molten into molten iron, and then the manganese iron, the chromium iron, the molybdenum iron, the vanadium iron, the red copper and the phosphorus iron are sequentially added into the molten iron in the medium frequency furnace;

[0089] Step 2, inoculation and modification treatment of the molten iron;

[0090] Step 2.1, according to the process requirement of horizontal continuous casting, the molten iron in the electric furnace in step 2 is poured into a ladle containing inoculant and modifier for primary inoculation and modification, and then the molten iron in the ladle is poured into a crystallizer for horizontal continuous casting of the profile;

[0091] The composition of the inoculant used for inoculation treatment is: 62-72% Si, 4-6% Ba, 2-3% Ca, 2-3% Mn, and the rest is Fe and unavoidable impurities. The inoculant used for primary inoculation is granular with a particle size of 0.5-1 mm; the addition amount of the primary inoculant is 0.4% of the total amount of molten iron; the modifier used for primary modification is granular with a particle size of 0.5-2 mm, and the amount is 0.8% of the total amount of molten iron.

[0092] Step 2.2, during the horizontal continuous casting of the profile, the step operation of the continuous casting profile is: stopping cooling for 0.5-3 min every 50 mm of drawing, synchronously supplementing modifier above the crystallizer to realize secondary collaborative inoculation and modification of the molten iron, and obtaining the profile which is dense and free of shrinkage holes, shrinkage porosity, gas holes and inclusions and slag inclusions existing in the castings produced by conventional casting methods.

[0093] Secondary collaborative inoculation adopts wire feeding inoculation, and the addition amount of the inoculant is 0.2% of the total amount of molten iron. The composition of the modifier used for modification is: 4.5-5.5% Mg, 7-8% Ti, 0.35-0.5% Ce, 4.0-4.5% Ca, 1.0-1.5% Al, 48-52% Si, and the rest is Fe and unavoidable impurities. Secondary collaborative modification adopts wire feeding, and the amount of the modifier is 0.4% of the total amount of molten iron.

[0094] The microstructure of the profile obtained after step 2 is: metal matrix (martensite + residual austenite) + vermicular graphite + spherical graphite, wherein the vermicular graphite accounts for more than 80% of the total volume of graphite, the size and spatial distribution of the vermicular graphite are uniform, the length of the vermicular graphite is about 10-25 um, and the diameter of the spherical graphite is about 20-30 um.

[0095] Step 3, immediately annealing the continuous casting profile;

[0096] The annealing temperature is 600°C, the annealing holding time is 5h, and after the annealing holding is completed, the furnace is cooled to 200°C first, and then the profile is taken out of the furnace and air cooled to room temperature.

[0097] Step 4, homogenizing annealing treatment is performed on the profile annealed in step 3;

[0098] The homogenizing annealing process is: 1050°C for 15h, and then the furnace is cooled to 500°C and the profile is taken out of the furnace and air cooled to room temperature.

[0099] Step 5, the homogenization annealing treated profile is processed into an aluminum alloy pressure casting mold, and then the mold is subjected to heat treatment quenching and tempering treatment, thereby obtaining the aluminum alloy pressure casting mold with excellent corrosion resistance to aluminum liquid. The profile has the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid pressure casting temperature.

[0100] The quenching heating temperature is 900℃, the quenching heating holding time is 1h, after the quenching heating holding is finished, the mold is rapidly quenched into quenching medium No. 20 machine oil or diesel oil or spindle oil; after being cooled in the oil for 5-10 seconds, the temperature of the mold is cooled to 200℃, and then the mold is placed into a heating furnace for tempering; the tempering temperature is 550℃, the tempering holding time is 3h, after the tempering holding is finished, the mold is taken out of the furnace and air-cooled to room temperature, and the obtained structure after the tempering is: sorbite + vermicular graphite + spherical graphite, and the hardness is not less than 45HRC. The profile has the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid pressure casting temperature.

[0101] Through the comparison test results of three embodiments and the existing materials, the service life of the aluminum alloy pressure casting mold made of the profile of the present application is increased by nearly 20% compared with the service life of the existing hot work die steel aluminum alloy pressure casting mold, and considering that the economy of the aluminum alloy pressure casting mold material of the present application is much better than that of the hot work die steel, the present application uses horizontal continuous casting process, through the design of molten iron composition, the control of inoculation and modification methods, and the control of molten iron solidification rate, the molten iron has the following advantages during the solidification process:

[0102] I. The hypereutectic composition of the alloy molten iron solidifies in the pseudo-eutectic zone to obtain the as-cast structure with uniform graphite size and distribution;

[0103] II. The molten iron is always solidified layer by layer and centripetally, the un-solidified core of the profile is always communicated with the molten iron in the crystallizer, the molten iron is always supplemented during the solidification process, and the gas, inclusions and slag inclusions precipitated during the solidification process can be removed by floating to slag, thereby obtaining the dense profile without shrinkage, shrinkage, porosity, slag inclusion and inclusion;

[0104] III. Controlling the morphology, size and distribution of graphite to obtain fine and uniformly distributed vermicular graphite which causes less damage to the mechanical properties of the metal matrix, imparts high thermal fatigue performance to the castings, and imparts excellent corrosion resistance of the metal matrix to the aluminum liquid, to obtain compact, defect-free and good mechanical property vermicular cast iron profiles; combined with heat treatment to regulate the mechanical properties of the profile, ultimately obtaining a profile with high strength, high hardness and good wear resistance at high temperature, high thermal fatigue resistance and excellent corrosion resistance to aluminum liquid. The profile meets the performance requirements of aluminum alloy die casting molds, and is used in the manufacture of aluminum alloy die casting molds. Due to the good mechanical properties, thermal fatigue performance, high hardness, high wear resistance, and excellent corrosion resistance to aluminum liquid of the profile, the service life of the aluminum alloy die casting mold made of the profile is higher than that of the existing hot work die steel aluminum alloy die casting mold.

[0105] The preparation method of the aluminum alloy die casting mold material of the present application prepares an aluminum alloy die casting mold profile with high strength, high hardness, high wear resistance, high thermal fatigue performance, high hardness and good wear resistance at high temperature, and excellent corrosion resistance to aluminum liquid. Through alloying composition design, solidification mode regulation during molten iron solidification, inoculation and modification control, and heat treatment regulation of the profile after forming, a profile with a structure of tempered sorbite + vermicular graphite + spherical graphite is obtained.

[0106] The carbide in the tempered sorbite is an alloy carbide of (Fe, Cr, Mo, V); the vermicular graphite accounts for more than 80% of the total volume of graphite, the size and spatial distribution of the vermicular graphite are uniform, the length of the vermicular graphite is about 10-25 um, and the diameter of the spherical graphite is about 20-30 um. The structure makes the aluminum alloy die casting mold prepared from the profile have the characteristics of high strength and hardness, good wear resistance, good thermal fatigue performance and excellent corrosion resistance to aluminum liquid at the aluminum liquid pressure casting temperature, meets the performance requirements of the mold material under service conditions, solves the mold failure problem caused by corrosion of the aluminum liquid in the work of the current aluminum alloy die casting mold, significantly prolongs the service life of the mold and improves the surface quality of the formed aluminum alloy die casting, and at the same time, the material has a very economical manufacturing cost, so the aluminum alloy die casting mold made of the material will have a positive impact on the progress of aluminum alloy die casting technology and the progress of lightweight manufacturing technology.

Claims

1. A material for aluminum alloy die-casting molds, characterized in that, The raw material composition by mass percentage includes: 3.6-3.9% C, 2.1-2.7% Si, ≤0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.3-0.8% Cu, with the remainder being Fe and unavoidable impurities; The morphological structure of the material used for the aluminum alloy die-casting mold includes: sorbite + vermicular graphite + spherical graphite; wherein, the carbides in the sorbite are alloy carbides of Fe, Cr, Mo and V; vermicular graphite accounts for more than 80% of the total graphite volume, and the size and spatial distribution of the vermicular graphite are uniform. The worm-like graphite has a length of 10-25 μm; The spherical graphite has a diameter of 20-30 μm; The specific steps are as follows: Step 1: Prepare, weigh, and melt the raw materials; Step 2: Inoculation and Deterioration Treatment of Molten Iron; Step 3: Immediately anneal the continuously cast profiles; Step 4: Perform homogenization annealing treatment on the annealed profiles from Step 3; Step 5: Process the homogenized annealed profile into an aluminum alloy die-casting mold, and then perform heat treatment quenching and tempering on the mold to obtain an aluminum alloy die-casting mold with excellent resistance to aluminum liquid corrosion. Step 3 is specifically implemented according to the following steps: the annealing temperature is 550-600℃, the annealing holding time is 5-8h, and after the annealing holding is completed, the furnace is first cooled to 200℃, and then the furnace is removed and air-cooled to room temperature. Step 4 is specifically implemented according to the following steps: the homogenization annealing process is: holding at 1050℃ for 12-15 hours, cooling in the furnace to 500℃, and then air-cooling to room temperature after being removed from the furnace. Step 5 is specifically implemented according to the following steps: the heat treatment quenching temperature is 900-920℃, the quenching holding time is 1-2h, after the quenching holding time is completed, the mold is quickly quenched into the quenching medium No. 20 machine oil, diesel oil or spindle oil; after cooling in the oil for 5-10 seconds, the temperature of the mold is cooled to 200℃, and then the mold is placed in the heating furnace for tempering; the tempering temperature is 530℃-550℃, the tempering holding time is 3-4h, after the tempering holding time is completed, the mold is removed from the furnace and air-cooled to room temperature. The microstructure obtained after tempering is: sorbite + vermicular graphite + spheroidal graphite, and the hardness is not less than 45HRC.

2. A method for preparing materials for aluminum alloy die-casting molds, comprising preparing the aluminum alloy die-casting mold material as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Prepare, weigh, and melt the raw materials; Step 2: Inoculation and Deterioration Treatment of Molten Iron; Step 3: Immediately anneal the continuously cast profiles; Step 4: Perform homogenization annealing treatment on the annealed profiles from Step 3; Step 5: Process the homogenized annealed profile into an aluminum alloy die-casting mold, and then perform heat treatment quenching and tempering on the mold to obtain an aluminum alloy die-casting mold with excellent resistance to aluminum liquid corrosion.

3. The method for preparing materials for aluminum alloy die-casting molds according to claim 2, characterized in that, Step 1 is implemented in the following steps: Step 1.1: Prepare and weigh the scrap steel, blast furnace iron or pig iron, ferrosilicon, ferromanganese, ferromolybdenum, ferrovanadium, copper, ferrophosphorus, inoculant, and vermicularizing agent according to the following raw material composition by mass percentage: 3.6-3.9% C, 2.1-2.7% Si, ≤0.4% Mn, 0.5-0.8% Cr, 1.5-2.0% Mo, 0.5-0.7% V, ≤0.1% P, 0.007-0.015% Mg, 0.01-0.03% Ce, ≤0.02% S, 0.3-0.8% Cu, with the remainder being Fe and unavoidable impurities. Step 1.2: Heat the prepared and weighed scrap steel, blast furnace iron or pig iron, and ferrosilicon in a medium-frequency melting furnace to 1550℃ to melt them into molten iron. Then, add ferromanganese, ferrochrome, ferromolybdenum, ferrovanadium, copper, and ferrophosphorus into the molten iron in the medium-frequency furnace in sequence.

4. The method for preparing materials for aluminum alloy die-casting molds according to claim 3, characterized in that, Step 2 is implemented in the following steps: Step 2.1: According to the process requirements of horizontal continuous casting, pour the molten iron from the medium frequency furnace in step 1.2 into a ladle containing inoculant and modifier to perform one inoculation and modification treatment on the molten iron. Then pour the molten iron from the ladle into the crystallization furnace for horizontal continuous casting of the profile. The inoculant used in the inoculation treatment consists of 62-72% Si, 4-6% Ba, 2-3% Ca, 2-3% Mn, with the remainder being Fe and unavoidable impurities. The inoculant used in the primary inoculation is granular with a particle size of 0.5-1 mm, and the amount added in the primary inoculation is 0.4% of the total molten iron. The modifier used in the primary modification treatment is granular with a particle size of 0.5-2 mm, and the amount used is 0.8% of the total molten iron. Step 2.2: During the horizontal continuous casting process of the profile, the stepping operation of the continuously cast profile is as follows: every 50mm of drawing requires stopping the cooling for 0.5-3 minutes, and the modifier is simultaneously added above the crystallization furnace; The secondary co-inoculation adopts the wire feeding inoculation method, and the amount of inoculant added is 0.2% of the total amount of molten iron. The modifier used in the modification treatment has the following composition: 4.5-5.5% Mg, 7-8% Ti, 0.35-0.5% Ce, 4.0-4.5% Ca, 1.0-1.5% Al, 48-52% Si, with the remainder being iron and unavoidable impurities. The secondary co-modification treatment adopts the wire feeding method, and the amount of modifier used accounts for 0.4% of the total amount of molten iron.

5. The method for preparing materials for aluminum alloy die-casting molds according to claim 2, characterized in that, Step 3 is specifically implemented according to the following steps: the annealing temperature is 550-600℃, the annealing holding time is 5-8h, after the annealing holding is completed, the furnace is first cooled to 200℃, and then the furnace is removed and air-cooled to room temperature.

6. The method for preparing materials for aluminum alloy die-casting molds according to claim 2, characterized in that, Step 4 is specifically implemented according to the following steps: The homogenization annealing process is: hold at 1050℃ for 12-15 hours, cool with the furnace to 500℃, and then air-cool to room temperature.

7. The method for preparing materials for aluminum alloy die-casting molds according to claim 2, characterized in that, Step 5 is specifically implemented according to the following steps: the heat treatment quenching temperature is 900-920℃, the quenching holding time is 1-2h, after the quenching holding time is completed, the mold is quickly quenched into the quenching medium No. 20 machine oil, diesel oil or spindle oil; after cooling in the oil for 5-10 seconds, the temperature of the mold is cooled to 200℃, and then the mold is placed in the heating furnace for tempering; the tempering temperature is 530℃-550℃, the tempering holding time is 3-4h, after the tempering holding time is completed, the mold is removed from the furnace and air-cooled to room temperature. The microstructure obtained after tempering is: sorbite + vermicular graphite + spheroidal graphite, and the hardness is not less than 45HRC.