Alloy casting and preparation method thereof

Abstract

The invention discloses an alloy casting and a preparation method thereof, and the alloy casting comprises the following components in percentage by mass based on the total mass of the alloy: 18-28% of chromium; 10 to 18% of nickel; 3-8% of molybdenum; 1-4% of tungsten; 0.5 to 2 percent of vanadium; cobalt: 2-6%; 0.1 to 0.3 percent of carbon; 0.8 to 1.8% of silicon; 0.6 to 1.6 percent of manganese; and the balance of iron. By adjusting the contents of chromium, nickel, molybdenum, titanium, niobium, copper and other elements, the yield strength, tensile strength and hardness of the alloy are remarkably improved. Wherein chromium and nickel provide basic corrosion resistance, molybdenum further enhances local corrosion resistance, titanium and niobium form carbides and nitrides, the effects of precipitation strengthening and grain refining are achieved, and copper improves the comprehensive performance of the alloy to a certain degree; impurities and gas are effectively removed by improving the process, the purity of the alloy is improved, casting, forging and heat treatment process parameters are accurately controlled, the alloy obtains a good organization structure and excellent mechanical properties, and the strength and hardness of the alloy are further improved through specific solid solution and aging treatment.

Description

Technical Field

[0001] The invention relates to the technical field of alloy castings, and in particular to an alloy casting and a preparation method thereof. Background Art

[0002] In many fields of modern industry, such as marine engineering, chemical industry, energy, etc., the performance requirements for alloy castings are becoming increasingly stringent. On the one hand, alloy castings are required to be able to serve stably for a long time in harsh corrosive environments and have excellent corrosion resistance to resist erosion by media such as seawater, acid and alkali solutions; on the other hand, in order to withstand complex mechanical loads, alloy castings must have high yield strength, tensile strength and hardness. However, traditional alloy castings often find it difficult to achieve a balance in these key properties. For example, some common corrosion-resistant alloys lack strength and hardness, while high-strength alloys may have poor corrosion resistance, which seriously limits the wide application of alloy castings in high-end industrial fields. Therefore, it is of great practical significance to develop an alloy casting that can simultaneously meet the requirements of high corrosion resistance, high yield strength, high tensile strength and high hardness. Summary of the invention

[0003] In order to overcome at least one defect described in the above-mentioned prior art, the present invention provides an alloy casting and a preparation method thereof. By adjusting the content of elements such as chromium, nickel, molybdenum, titanium, niobium, and copper, the yield strength, tensile strength, and hardness of the alloy are significantly improved while ensuring good corrosion resistance. Among them, chromium and nickel provide basic corrosion resistance, molybdenum further enhances the ability to resist local corrosion, titanium and niobium form carbides and nitrides, which play a role in precipitation strengthening and grain refinement, and copper improves the comprehensive properties of the alloy to a certain extent; by improving the process to effectively remove impurities and gases, improve the purity of the alloy, accurately control the casting, forging, and heat treatment process parameters, so that the alloy obtains a good organizational structure and excellent mechanical properties, and through specific solid solution and aging treatment, the strength and hardness of the alloy are further improved.

[0004] The technical solution adopted by the present invention to solve the problem is:

[0005] An alloy casting, based on the total mass of the alloy, comprises, by mass percentage, chromium: 18-28%, nickel: 10-18%, molybdenum: 3-8%, tungsten: 1-4%, vanadium: 0.5-2%, cobalt: 2-6%, carbon: 0.1-0.3%, silicon: 0.8-1.8%, manganese: 0.6-1.6%, and the balance of iron.

[0006] A method for preparing an alloy casting, comprising the above-mentioned alloy casting, and the preparation method comprises the following steps:

[0007] S1. Raw material preparation: accurately weigh high-purity metal raw materials according to the above chemical composition ratio, including electrolytic chromium, electrolytic nickel, ferromolybdenum, ferrotungsten, ferrovanadium, metallic cobalt, graphite, ferrosilicon, ferromanganese and pure iron;

[0008] S2, smelting: adding the prepared raw materials into a vacuum arc furnace for smelting;

[0009] S3, refining: after the smelting is completed, high-purity argon gas is introduced into the vacuum arc furnace for refining;

[0010] S4, casting: the refined alloy liquid is cast into a preheated metal mold to form an alloy ingot;

[0011] S5, forging: heating the alloy ingot, keeping it warm, and then forging it, and then air cooling it to room temperature after forging;

[0012] S6. Heat treatment: After casting, the casting is first subjected to solution treatment, the casting is heated and kept warm, and then quickly quenched in water; then aging treatment is carried out, heating and keeping warm, and finally air cooling to room temperature.

[0013] Furthermore, among the metal raw materials in step S1, the purity of the raw materials of electrolytic chromium, electrolytic nickel, ferromolybdenum, sponge titanium, ferroniobium, electrolytic copper, pure iron, graphite, ferrosilicon and ferromanganese is above 99%.

[0014] Furthermore, in step S2, the pressure in the vacuum arc furnace is evacuated to less than 1×10-3Pa, and then the furnace temperature is raised to 1500-1600°C at a heating rate of 10-15°C / min, and kept at this temperature for 30-60 minutes to fully melt and evenly mix the raw materials.

[0015] Furthermore, electromagnetic stirring is performed during smelting in step S2, with a stirring frequency of 20-30 Hz to promote component homogenization.

[0016] Furthermore, in step S3, the high-purity argon gas flow rate is 5-10 L / min and the refining time is 10-20 minutes to remove impurities and gases in the alloy liquid.

[0017] Furthermore, in step S4, the alloy liquid is cast at 1400-1500°C into a metal mold preheated to 800-1000°C.

[0018] Furthermore, in step S5, the alloy ingot is heated to 1100-1200°C, kept warm for 1-2 hours, and then forged, with a forging ratio of 5-8, an initial forging temperature of 1050-1150°C, and a final forging temperature of not less than 900°C.

[0019] Furthermore, in step S6, the forged alloy component is subjected to a solution treatment by heating to 1000-1100°C, keeping the temperature for 1-2 hours, and then water quenching; followed by an aging treatment by heating to 500-600°C, keeping the temperature for 3-5 hours, and then air cooling to room temperature.

[0020] In summary, the alloy casting and the preparation method thereof provided by the present invention have the following technical effects:

[0021] 1. By adjusting the content of chromium, nickel, molybdenum, titanium, niobium, copper and other elements, the yield strength, tensile strength and hardness of the alloy are significantly improved while ensuring good corrosion resistance. Among them, chromium and nickel provide basic corrosion resistance, molybdenum further enhances the ability to resist local corrosion, titanium and niobium form carbides and nitrides, which play a role in precipitation strengthening and grain refinement, and copper improves the comprehensive performance of the alloy to a certain extent;

[0022] 2. Through improved processes, impurities and gases are effectively removed to improve the purity of the alloy, and casting, forging and heat treatment process parameters are precisely controlled to enable the alloy to obtain a good organizational structure and excellent mechanical properties. Furthermore, through specific solid solution and aging treatments, the strength and hardness of the alloy are further improved;

[0023] 3. Its high corrosion resistance can reduce corrosion damage in harsh environments, and its high yield strength, tensile strength and hardness can withstand greater loads and stresses, thereby extending the service life of the equipment, reducing maintenance costs, and improving the reliability and safety of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of an embodiment of the present invention; DETAILED DESCRIPTION

[0025] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described and discussed below in conjunction with the accompanying drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all the examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] In order to facilitate the understanding of the embodiments of the present invention, the following will be further explained by taking specific embodiments as examples in conjunction with the drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0027] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0029] See also Figure 1 , the present invention is further described below in conjunction with specific embodiments.

[0030] Embodiment 1:

[0031] Raw material preparation: weigh pure metal raw materials including chromium (Cr): 15%, nickel (Ni): 8%, molybdenum (Mo): 2%, titanium (Ti): 0.5%, niobium (Nb): 0.5%, copper (Cu): 1%, carbon (C): 0.05%, silicon (Si): 0.5%, manganese (Mn): 0.5%, and the remainder is iron (Fe) and inevitable impurities.

[0032] Melting: In a vacuum induction furnace, evacuate the furnace to a pressure of 0.8×10-3Pa, heat to 1500°C at a rate of 10°C / min, keep warm for 30 minutes, and use an electromagnetic stirring frequency of 20Hz.

[0033] Refining: introduce argon gas at a flow rate of 5 L / min and refine for 10 minutes.

[0034] Casting: Cast at 1400℃ into a metal mold preheated to 800℃.

[0035] Forging: heat to 1100℃, keep warm for 1 hour, forging ratio 5, initial forging temperature 1050℃, final forging temperature 900℃, air cooling.

[0036] Heat treatment: solution treatment at 1000℃, keep warm for 1 hour, water quench; aging treatment at 500℃, keep warm for 3 hours, air cooling.

[0037] After testing, the yield strength is 650MPa, the tensile strength is 900MPa, the hardness is 300HB, and the corrosion rate in 3.5% NaCl solution is 0.05mm / year.

[0038] Embodiment 2:

[0039] Raw material preparation: chromium (Cr): 18%, nickel (Ni): 10%, molybdenum (Mo): 3%, titanium (Ti): 1%, niobium (Nb): 1%, copper (Cu): 2%, carbon (C): 0.1%, silicon (Si): 1%, manganese (Mn): 1%, and the balance is iron (Fe).

[0040] Melting: The pressure in the vacuum induction furnace is 0.9×10-3Pa, the temperature is raised to 1550°C, and the temperature is kept for 40 minutes. The electromagnetic stirring frequency is 25Hz.

[0041] Refining: Argon flow rate 8L / min, refining for 15 minutes.

[0042] Casting: Cast at 1450℃ and preheat the mold to 900℃.

[0043] Forging: heat to 1150℃, keep warm for 1.5 hours, forging ratio 6, initial forging temperature 1100℃, final forging temperature 920℃, air cooling.

[0044] Heat treatment: solution treatment at 1050℃, hold for 1.5 hours, water quenching; aging treatment at 550℃, hold for 4 hours, air cooling.

[0045] After testing, the yield strength is 720MPa, the tensile strength is 1000MPa, the hardness is 320HB, and the corrosion rate in 3.5% NaCl solution is 0.03mm / year.

[0046] Embodiment 3:

[0047] Raw material preparation: chromium (Cr): 20%, nickel (Ni): 12%, molybdenum (Mo): 4%, titanium (Ti): 1.5%, niobium (Nb): 1.5%, copper (Cu): 2.5%, carbon (C): 0.15%, silicon (Si): 1.2%, manganese (Mn): 1.2%, and the balance is iron (Fe).

[0048] Melting: furnace pressure 1×10-3Pa, temperature raised to 1580°C, kept warm for 50 minutes, electromagnetic stirring frequency 28Hz.

[0049] Refining: Argon flow rate 9 L / min, refining for 18 minutes.

[0050] Casting: 1480℃ casting into 950℃ mold.

[0051] Forging: heat to 1180℃, keep warm for 1.8 hours, forging ratio 7, initial forging temperature 1120℃, final forging temperature 950℃, air cooling.

[0052] Heat treatment: solution treatment at 1080°C, hold for 1.8 hours, water quenching; aging treatment at 580°C, hold for 4.5 hours, air cooling.

[0053] After testing, the yield strength is 780MPa, the tensile strength is 1080MPa, the hardness is 350HB, and the corrosion rate in 3.5% NaCl solution is 0.02mm / year.

[0054] Embodiment 4:

[0055] Raw material preparation: chromium (Cr): 22%, nickel (Ni): 13%, molybdenum (Mo): 5%, titanium (Ti): 1.8%, niobium (Nb): 1.8%, copper (Cu): 2.8%, carbon (C): 0.18%, silicon (Si): 1.3%, manganese (Mn): 1.3%, and the balance is iron (Fe).

[0056] Melting: furnace pressure 0.95×10-3Pa, temperature raised to 1560°C, kept warm for 45 minutes, electromagnetic stirring frequency 26Hz.

[0057] Refining: Argon flow rate 7 L / min, refining for 16 minutes.

[0058] Casting: 1460℃ casting into 920℃ mold.

[0059] Forging: heat to 1160℃, keep warm for 1.6 hours, forging ratio 6.5, initial forging temperature 1110℃, final forging temperature 930℃, air cooling.

[0060] Heat treatment: solution treatment at 1060°C, hold for 1.6 hours, water quenching; aging treatment at 560°C, hold for 4.2 hours, air cooling.

[0061] After testing, the yield strength is 800MPa, the tensile strength is 1100MPa, the hardness is 360HB, and the corrosion rate in 3.5% NaCl solution is 0.015mm / year.

[0062] Embodiment 5:

[0063] Raw material preparation: chromium (Cr): 25%, nickel (Ni): 15%, molybdenum (Mo): 6%, titanium (Ti): 2%, niobium (Nb): 2%, copper (Cu): 3%, carbon (C): 0.2%, silicon (Si): 1.5%, manganese (Mn): 1.5%, and the balance is iron (Fe).

[0064] Melting: furnace pressure 1.1×10-3Pa, temperature raised to 1600°C, kept warm for 60 minutes, electromagnetic stirring frequency 30Hz.

[0065] Refining: Argon flow rate 10L / min, refining for 20 minutes.

[0066] Casting: 1500℃ casting into 1000℃ mold.

[0067] Forging: heat to 1200℃, keep warm for 2 hours, forging ratio 8, initial forging temperature 1150℃, final forging temperature 980℃, air cooling.

[0068] Heat treatment: solution treatment at 1100℃, hold for 2 hours, water quenching; aging at 600℃, hold for 5 hours, air cooling.

[0069] After testing, the yield strength is 850MPa, the tensile strength is 1150MPa, the hardness is 380HB, and the corrosion rate in 3.5% NaCl solution is 0.01mm / year.

[0070] Embodiment 6:

[0071] Raw material preparation: chromium (Cr): 16%, nickel (Ni): 9%, molybdenum (Mo): 2.5%, titanium (Ti): 0.8%, niobium (Nb): 0.8%, copper (Cu): 1.5%, carbon (C): 0.08%, silicon (Si): 0.8%, manganese (Mn): 0.8%, and the balance is iron (Fe).

[0072] Melting: furnace pressure 0.7×10-3Pa, temperature raised to 1520°C, kept warm for 35 minutes, electromagnetic stirring frequency 22Hz.

[0073] Refining: Argon flow rate 6L / min, refining for 12 minutes.

[0074] Casting: 1420℃ casting into 850℃ mold.

[0075] Forging: heat to 1120℃, keep warm for 1.2 hours, forging ratio 5.5, initial forging temperature 1060℃, final forging temperature 910℃, air cooling.

[0076] Heat treatment: solution treatment at 1020℃, hold for 1.2 hours, water quenching; aging treatment at 520℃, hold for 3.5 hours, air cooling.

[0077] After testing, the yield strength is 680MPa, the tensile strength is 950MPa, the hardness is 310HB, and the corrosion rate in 3.5% NaCl solution is 0.06mm / year.

[0078] Embodiment 7:

[0079] Raw material preparation: chromium (Cr): 19%, nickel (Ni): 11%, molybdenum (Mo): 3.5%, titanium (Ti): 1.2%, niobium (Nb): 1.2%, copper (Cu): 2.2%, carbon (C): 0.12%, silicon (Si): 1.1%, manganese (Mn): 1.1%, and the balance is iron (Fe).

[0080] Melting: furnace pressure 0.92×10-3Pa, temperature raised to 1570°C, kept warm for 48 minutes, electromagnetic stirring frequency 27Hz.

[0081] Refining: Argon flow rate 9.5 L / min, refining for 19 minutes.

[0082] Casting: 1470℃ casting into 980℃ mold.

[0083] Forging: heat to 1170℃, keep warm for 1.7 hours, forging ratio 6.8, initial forging temperature 1130℃, final forging temperature 960℃, air cooling.

[0084] Heat treatment: solution treatment at 1070℃, hold for 1.7 hours, water quenching; aging treatment at 570℃, hold for 4.8 hours, air cooling.

[0085] After testing, the yield strength is 750MPa, the tensile strength is 1050MPa, the hardness is 330HB, and the corrosion rate in 3.5% NaCl solution is 0.04mm / year.

[0086] Example 8

[0087] Raw material preparation: chromium (Cr): 21%, nickel (Ni): 14%, molybdenum (Mo): 4.5%, titanium (Ti): 1.6%, niobium (Nb): 1.6%, copper (Cu): 2.6%, carbon (C): 0.16%, silicon (Si): 1.4%, manganese (Mn): 1.4%, and the balance is iron (Fe).

[0088] Melting: furnace pressure 1.05×10-3Pa, temperature raised to 1590°C, kept warm for 55 minutes, electromagnetic stirring frequency 29Hz.

[0089] Refining: Argon flow rate 9.8 L / min, refining for 19.5 minutes.

[0090] Casting: 1490℃ casting into 990℃ mold.

[0091] Forging: heat to 1190℃, keep warm for 1.9 hours, forging ratio 7.5, initial forging temperature 1140℃, final forging temperature 970℃, air cooling.

[0092] Heat treatment: solution treatment at 1090℃, holding temperature for 1.9 hours, water quenching; aging treatment at 590℃, holding temperature for 4.9 hours, air cooling.

[0093] The tested yield strength is 820MPa, the tensile strength is 1120MPa, the hardness is 370HB, and the corrosion rate in 3.5% NaCl solution is 0.018mm / year.

[0094] Example 9

[0095] Raw material preparation: chromium (Cr): 23%, nickel (Ni): 13.5%, molybdenum (Mo): 5.5%, titanium (Ti): 1.9%, niobium (Nb): 1.9%, copper (Cu): 2.9%, carbon (C): 0.19%, silicon (Si): 1.35%, manganese (Mn): 1.35%, and the balance is iron (Fe).

[0096] Melting: furnace pressure 1.02×10-3Pa, temperature raised to 1575°C, heat preservation for 52 minutes, electromagnetic stirring frequency 28.5Hz.

[0097] Refining: Argon flow rate 9.2 L / min, refining for 18.5 minutes.

[0098] Casting: 1475℃ casting into 960℃ mold.

[0099] Forging: heat to 1175℃, keep warm for 1.75 hours, forging ratio 7.2, initial forging temperature 1135℃, final forging temperature 965℃, air cooling.

[0100] Heat treatment: solution treatment at 1075°C, hold for 1.75 hours, water quenching; aging treatment at 585°C, hold for 4.7 hours, air cooling.

[0101] After testing, the yield strength is 830MPa, the tensile strength is 1130MPa, the hardness is 375HB, and the corrosion rate in 3.5% NaCl solution is 0.016mm / year.

[0102] Example 10

[0103] Raw material preparation: chromium (Cr): 24%, nickel (Ni): 14.5%, molybdenum (Mo): 5.8%, titanium (T i): 1.95%, niobium (Nb): 1.95%, copper (Cu): 2.95%, carbon (C): 0.195%, silicon (Si): 1.45%, manganese (Mn): 1.45%, and the balance is iron (Fe).

[0104] Melting: furnace pressure 1.08×10-3Pa, temperature raised to 1595°C, kept warm for 58 minutes, electromagnetic stirring frequency 29.5Hz.

[0105] Refining: Argon flow rate 9.6 L / min, refining 19.2 minutes.

[0106] Casting: 1495℃ casting into 995℃ mold.

[0107] Forging: heat to 1195℃, keep warm for 1.95 hours, forging ratio 7.8, initial forging temperature 1145℃, final forging temperature 975℃, air cooling.

[0108] Heat treatment: solution treatment at 1095℃, holding for 1.95 hours, water quenching; aging treatment at 595℃, holding for 4.95 hours, air cooling.

[0109] The yield strength is 840MPa, the tensile strength is 1140MPa, the hardness is 378HB, and the corrosion rate in 3.5% NaCl solution is 0.012mm / year.

[0110] Table 1 Experimental data of Examples 1-10

[0111]

[0112] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. An alloy casting, characterized in that: Based on the total mass of the alloy, the components by mass percentage include: Chromium: 18-28%; Nickel: 10-18%; Molybdenum: 3-8%; Tungsten: 1-4%; Vanadium: 0.5-2%; Cobalt: 2-6%; Carbon: 0.1-0.3%; Silicon: 0.8-1.8%; Manganese: 0.6-1.6%; and the balance iron.

2. A method for preparing an alloy casting, characterized in that: The alloy casting according to claim 1 is prepared by the following steps: S1. Raw material preparation: accurately weigh high-purity metal raw materials according to the above chemical composition ratio, including electrolytic chromium, electrolytic nickel, ferromolybdenum, ferrotungsten, ferrovanadium, metallic cobalt, graphite, ferrosilicon, ferromanganese and pure iron; S2, smelting: adding the prepared raw materials into a vacuum arc furnace for smelting; S3, refining: after the smelting is completed, high-purity argon gas is introduced into the vacuum arc furnace for refining; S4, casting: the refined alloy liquid is cast into a preheated metal mold to form an alloy ingot; S5, forging: heating the alloy ingot, keeping it warm, and then forging it, and then air cooling it to room temperature after forging; S6. Heat treatment: After casting, the casting is first subjected to solution treatment, the casting is heated and kept warm, and then quickly quenched in water; then aging treatment is carried out, heating and keeping warm, and finally air cooling to room temperature.

3. The method for preparing an alloy casting according to claim 2, characterized in that: Among the metal raw materials in step S1, the purity of the raw materials of electrolytic chromium, electrolytic nickel, ferromolybdenum, sponge titanium, ferroniobium, electrolytic copper, pure iron, graphite, ferrosilicon and ferromanganese is all above 99%.

4. The method for preparing an alloy casting according to claim 2, characterized in that: In step S2, the pressure in the vacuum arc furnace is evacuated to less than 1×10-3Pa, and then the furnace temperature is raised to 1500-1600°C at a heating rate of 10-15°C / min, and kept at this temperature for 30-60 minutes to fully melt the raw materials and mix them evenly.

5. The method for preparing an alloy casting according to claim 4, characterized in that: During the smelting in step S2, electromagnetic stirring is performed with a stirring frequency of 20-30 Hz to promote the homogenization of the components.

6. The method for preparing an alloy casting according to claim 2, characterized in that: In step S3, the high-purity argon gas flow rate is 5-10 L / min and the refining time is 10-20 minutes to remove impurities and gases in the alloy liquid.

7. The method for preparing an alloy casting according to claim 2, characterized in that: In step S4, the alloy liquid is cast at 1400-1500°C into a metal mold preheated to 800-1000°C.

8. The method for preparing an alloy casting according to claim 2, characterized in that: In step S5, the alloy ingot is heated to 1100-1200°C, kept warm for 1-2 hours, and then forged, with a forging ratio of 5-8, an initial forging temperature of 1050-1150°C, and a final forging temperature of not less than 900°C.

9. The method for preparing an alloy casting according to claim 2, characterized in that: In step S6, the forged alloy component is subjected to a solution treatment by heating to 1000-1100°C, keeping the temperature for 1-2 hours, and then water quenching; followed by an aging treatment by heating to 500-600°C, keeping the temperature for 3-5 hours, and then air cooling to room temperature.

Images