LCC steel with excellent low-temperature impact toughness

Abstract

The invention discloses LCC steel with excellent low-temperature impact toughness. The LCC steel comprises carbon, silicon, manganese, chromium, nickel, molybdenum, copper, aluminum, iron and impurities. According to the LCC steel with the excellent low-temperature impact toughness, through proper alloy element design, the toughness of steel can be improved at the low temperature, the risk of brittle fracture is reduced, the reliability of the steel in the low-temperature environment is guaranteed, the casting technology and the heat treatment technology are further optimized, and the production cost is reduced. And the low-temperature impact toughness and the brittle fracture resistance of the steel are further enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to an LCC steel with excellent low-temperature impact toughness. Background Art

[0002] LCC steel (Low Carbon Cast Steel) is widely used in the fields of construction, machinery, automobiles, etc., with excellent casting performance and good mechanical properties. However, the existing LCC steel has poor impact toughness in low temperature environment and is prone to brittle fracture at low temperature, which limits its use in low temperature working conditions. Therefore, improving the low temperature impact toughness of LCC steel is the key to improving its application performance. Summary of the invention

[0003] The present invention aims to solve one of the technical problems in the above-mentioned technology at least to some extent.

[0004] To achieve the above-mentioned purpose, the first aspect of the present invention provides an LCC steel with excellent low-temperature impact toughness, the chemical composition of the LCC steel comprising, by mass percentage: carbon: 0.10% to 0.25%; silicon: 0.20% to 1.50%; manganese; 0.50% to 1.50%; chromium: 0.50% to 1.50%; nickel: 1.00% to 3.00%; molybdenum: 0.10% to 0.50%; copper: 0.50% to 2.00%; aluminum: 0.015% to 0.060%; the rest is iron and unavoidable impurities.

[0005] In addition, the LCC steel with excellent low temperature impact toughness proposed in the present invention may also have the following additional technical features:

[0006] Furthermore, the nickel content is 1.50% to 2.50%, the chromium content is 0.80% to 1.20%, the molybdenum content is 0.20% to 0.40%, and the copper content is 1.00% to 1.80%.

[0007] Furthermore, the casting temperature of the LCC steel during the casting process is 1550°C to 1650°C, and the cooling method is natural cooling or controlled cooling.

[0008] Furthermore, the LCC steel is subjected to a solution treatment after casting, the solution temperature is 900° C. to 1050° C., the holding time is 1 to 2 hours, and then air cooling or water cooling is performed.

[0009] Furthermore, the low temperature impact toughness of the LCC steel has a Charpy impact value of not less than 50J at -40°C.

[0010] Furthermore, the grain size of the LCC steel is 5 to 7, and the microstructure contains fine martensite and bainite structures, and the microhardness does not exceed 250 HV.

[0011] To achieve the above-mentioned purpose, the second aspect of the present invention proposes a method for producing LCC steel with excellent low-temperature impact toughness, comprising the following steps: preparing materials according to the chemical composition of claim 1; S2: casting at a temperature of 1550°C to 1650°C, and controlling the cooling rate during the casting process; S3: after the casting is cooled, solution treatment is performed at a solution temperature of 900°C to 1050°C, and the temperature is kept for 1 to 2 hours; S4: air cooling or water cooling is performed to achieve the desired organizational structure; S5: finally, a low-temperature impact test is performed to ensure that the impact toughness of the material is not less than 50J.

[0012] In addition, the method for producing LCC steel with excellent low temperature impact toughness according to the present invention may also have the following additional technical features:

[0013] Furthermore, after the solution treatment, an aging treatment may be performed at a temperature of 500° C. to 600° C. and a holding time of 2 to 4 hours to further improve the toughness of the material.

[0014] According to the LCC steel with excellent low-temperature impact toughness of the present invention, the toughness of the steel can be improved at low temperatures, the risk of brittle fracture can be reduced, and its reliability in low-temperature environments can be ensured through appropriate alloy element design. The present invention also optimizes the casting process and heat treatment process to further enhance the low-temperature impact toughness and brittle fracture resistance of the steel. DETAILED DESCRIPTION

[0015] The embodiment of the present invention provides an LCC steel with excellent low-temperature impact toughness. The chemical composition of the LCC steel comprises, by mass percentage, carbon: 0.10% to 0.25%, silicon: 0.20% to 1.50%, manganese: 0.50% to 1.50%, chromium: 0.50% to 1.50%, nickel: 1.00% to 3.00%, molybdenum: 0.10% to 0.50%, copper: 0.50% to 2.00%, aluminum: 0.015% to 0.060%, and the rest is iron and unavoidable impurities.

[0018] It should be noted that the nickel content is 1.50% to 2.50%, the chromium content is 0.80% to 1.20%, the molybdenum content is 0.20% to 0.40%, and the copper content is 1.00% to 1.80%.

[0019] It should be noted that the casting temperature of the LCC steel during the casting process is 1550° C. to 1650° C., and the cooling method is natural cooling or controlled cooling.

[0020] It should be noted that the LCC steel is subjected to solution treatment after casting, the solution temperature is 900° C. to 1050° C., the holding time is 1 to 2 hours, and then air cooling or water cooling is performed.

[0021] It should be noted that the low temperature impact toughness of the LCC steel has a Charpy impact value of not less than 50J at -40°C.

[0022] It should be noted that the grain size of the LCC steel is 5 to 7, and the microstructure contains fine martensite and bainite structures, and the microhardness does not exceed 250 HV.

[0023] It should be noted that the brittle fracture resistance of the steel in low temperature environment is improved by more than 30% compared with the prior art materials.

[0024] It should be noted that by adjusting the content of alloy elements in the steel (such as adding elements such as nickel, chromium, molybdenum, and copper), the LCC steel of the present invention exhibits good impact toughness under low temperature conditions. Compared with traditional LCC steel, the Charpy impact value of the material of the present invention at -40°C is increased by more than 30%, which can effectively reduce brittle fracture in low temperature environments and ensure its safe use under harsh climatic conditions.

[0025] It should be noted that the LCC steel of the present invention improves the grain structure of the material through alloy design and organizational optimization, so that the brittle fracture resistance of the steel is significantly improved. In a low-temperature working environment, the material exhibits a higher brittle fracture resistance and is suitable for key structural parts in a low-temperature environment, such as cryogenic equipment, transportation pipelines, etc.

[0026] A method for producing LCC steel with excellent low-temperature impact toughness according to an embodiment of the present invention comprises the following steps: S1: preparing materials according to the chemical composition of claim 1, S2: casting at a temperature of 1550°C to 1650°C, and controlling the cooling rate during the casting process, S3: performing solid solution treatment after the casting is cooled, the solid solution temperature is 900°C to 1050°C, and the temperature is kept for 1 to 2 hours, S4: air cooling or water cooling to achieve the desired organizational structure, S5: finally performing a low-temperature impact test to ensure that the impact toughness of the material is not less than 50J.

[0027] It should be noted that after the solution treatment, an aging treatment may be performed at a temperature of 500° C. to 600° C. and a holding time of 2 to 4 hours to further improve the toughness of the material.

[0028] It should be noted that the optimized casting process (including controlling the casting temperature and cooling rate) and the subsequent solution treatment process adopted by the present invention ensure the casting performance of the steel, and can effectively eliminate the internal defects of the casting to obtain a uniform organizational structure. Through appropriate aging treatment, the low-temperature impact toughness of the material is further improved, ensuring that the steel has good processing performance and long-term stability in practical applications.

[0029] In summary, according to an embodiment of the present invention, an LCC steel with excellent low-temperature impact toughness can improve the toughness of the steel at low temperatures, reduce the risk of brittle fracture, and ensure its reliability in a low-temperature environment through appropriate alloy element design. The present invention also optimizes the casting process and heat treatment process to further enhance the low-temperature impact toughness and brittle fracture resistance of the steel.

[0030] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0032] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A LCC steel with excellent low temperature impact toughness, characterized in that: The chemical composition of the LCC steel comprises by mass percentage: Carbon: 0.10%~0.25%; Silicon: 0.20% to 1.50%; Manganese: 0.50%~1.50%; Chromium: 0.50% to 1.50%; Nickel: 1.00%~3.00%; Molybdenum: 0.10%~0.50%; Copper: 0.50%~2.00%; Aluminum: 0.015% to 0.060%; The rest is iron and inevitable impurities.

2. The LCC steel with excellent low temperature impact toughness according to claim 1, characterized in that: The nickel content is 1.50% to 2.50%, the chromium content is 0.80% to 1.20%, the molybdenum content is 0.20% to 0.40%, and the copper content is 1.00% to 1.80%.

3. The LCC steel with excellent low temperature impact toughness according to claim 1 or 2, characterized in that: The casting temperature of the LCC steel during the casting process is 1550° C. to 1650° C., and the cooling method is natural cooling or controlled cooling.

4. The LCC steel with excellent low temperature impact toughness according to claim 3, characterized in that: The LCC steel is subjected to solution treatment after casting, the solution temperature is 900°C to 1050°C, the heat preservation time is 1 to 2 hours, and then air cooling or water cooling is performed.

5. The LCC steel with excellent low temperature impact toughness according to claim 1, characterized in that: The low temperature impact toughness of the LCC steel has a Charpy impact value of not less than 50J at -40°C.

6. The LCC steel with excellent low temperature impact toughness according to claim 1, characterized in that: The LCC steel has a grain size of 5 to 7, contains fine martensite and bainite structures in its structure, and has a microhardness of no more than 250 HV.

7. A method for preparing LCC steel with excellent low temperature impact toughness, characterized in that: The following steps are involved: S1: a chemical composition according to claim 1; S2: Casting at a temperature of 1550°C to 1650°C, and controlling the cooling rate during the casting process; S3: After the casting is cooled, solution treatment is performed at a temperature of 900°C to 1050°C for 1 to 2 hours; S4: air cooling or water cooling to achieve the desired organizational structure; S5: Finally, a low temperature impact test is performed to ensure that the impact toughness of the material is not less than 50J.

8. The method for preparing LCC steel with excellent low temperature impact toughness according to claim 7, characterized in that: After the solution treatment, an aging treatment may be performed at a temperature of 500° C. to 600° C. and a holding time of 2 to 4 hours to further improve the toughness of the material.