Die casting process method of 0Cr11 steel

Abstract

The invention relates to a die casting process method for 0Cr11 steel, which comprises the following steps of: 1) pouring a steel ingot by adopting a die casting method, and controlling the casting starting superheat degree of die casting to be 50-60 DEG C; (2) the ingot body pouring time is controlled to be 8-12 min; (3) the cap opening filling time is longer than 6 min; 4) adding an exothermic agent at a position 1 / 2-2 / 3 away from the top of the cap opening above the molten steel, and adding 2-4kg of a heat preservation agent after the exothermic agent begins to burn; and (5) when molten steel is poured, an argon sealing ring is adopted to block air, and asbestos felt is additionally arranged on the argon sealing ring to prevent secondary oxidation. By the adoption of the method, defects generated in the die casting process can be effectively reduced, the quality of steel ingots is improved, it is guaranteed that the quality of rolled products meets the requirement, the flaw detection qualification rate of rolled blanks is increased, the whole-line yield is increased, and the problem of quality control in the casting process is solved.

Description

Technical Field

[0001] The invention relates to the technical field of casting, and in particular to a die casting process method for 0Cr11 steel. Background Art

[0002] 0Cr11 steel has good formability, economy, corrosion resistance, oxidation resistance and other comprehensive properties, and is mainly used in the manufacture of chemical containers and pipelines. Since 0Cr11 steel can maintain good stability in high temperature and corrosive environments, and has good welding performance, it is easy to process and manufacture, and can meet the production requirements of automobile exhaust system components, its application in the automobile industry is gradually increasing.

[0003] In recent years, in order to improve the exhaust purification efficiency of automobiles and achieve lightweight automobiles, the exhaust pipes originally made of cast iron have been gradually replaced by exhaust pipes made of 0Cr11 steel. However, when manufacturing exhaust pipes made of 0Cr11 steel, due to the large ingot size (about 8.4t) during die casting, as well as the special chemical composition and solidification characteristics, the steel ingot is prone to shrinkage, looseness, internal cracks and other defects, and cannot be welded during the subsequent forging process, resulting in a low pass rate during the flaw detection of the finished product. Even shrinkage defects can still be found in the low-power inspection after forging, resulting in a low yield rate, increasing the economic losses of the enterprise and increasing production costs. Therefore, the die casting process control of 0Cr11 steel is the focus and difficulty of product quality control at this stage.

[0004] The US patent application with publication number US20130015318A1 discloses a "layered crucible for casting silicates and its production method", which achieves the purpose of reducing the oxygen concentration in the silicon ingot by setting a silicon dioxide layer in the layered crucible and a barium coating on its surface. The use of the layered crucible produced by the method in the solar cell unit can improve the photoelectric conversion efficiency of the cell. However, this method can only be applied to the casting of small silicon ingots and cannot be applied to the casting process of large rack steel ingots. In addition, the production process is complicated and the crucible is expensive, which increases the production cost and is difficult to popularize and promote.

[0005] European patent application with publication number EP0597113A1 discloses a "method for continuous production of double-layer metal materials". When using this technology to continuously cast and produce double-layer metal materials, it is possible to achieve improvements in the separation of components between the surface layer and the inner layer, and to produce double-layer metal materials with uniform thickness on the surface layer. However, this method has great limitations and cannot solve the segregation and shrinkage problems during the solidification of large rack steel ingots. It also has the disadvantages of complex production process, long process, poor continuous production capacity, etc., and cannot achieve large-scale mass production.

[0006] The Chinese invention patent with the authorization announcement number CN103317106B discloses "a method and device for improving the casting quality of large steel ingots", which improves heat and mass transfer, purifies the steel liquid by electromagnetic stirring of the cross section, suppresses the liquid level fluctuation caused by the steel liquid filling, and has a certain improvement effect on preventing defects such as heavy skin of the steel ingot. However, this method has almost no improvement on the internal quality of large rack steel ingots, and the equipment is too cumbersome and costly, and is not suitable for continuous production of large ingots. Summary of the invention

[0007] The invention provides a die casting process method for 0Cr11 steel. By studying the ingot shape, the solidification mechanism of molten steel, and the influence of factors such as the ingot mold, the molten steel temperature and the pouring speed on the defects of the ingot, the solidification process of the molten steel is controlled, the density of the ingot is improved, the generation of defects such as shrinkage cavities, looseness and cracks is reduced, and the surface quality of the ingot is guaranteed. The invention can effectively reduce the defects generated in the die casting process, improve the quality of the ingot, ensure that the quality of the product after rolling meets the requirements, improve the flaw detection pass rate of the rolled billet, improve the yield rate of the whole line, and solve the difficulty of quality control in the casting process.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] A die casting process method for 0Cr11 steel controls the following processes:

[0010] 1) The steel ingot is cast by the mold casting method. The molten steel with qualified composition is poured into the steel ingot mold. The superheat of the mold casting is controlled at 50-60℃;

[0011] 2) The ingot casting time is controlled within 8 to 12 minutes;

[0012] 3) Cap filling time> 6min;

[0013] 4) Add exothermic agent at 1 / 2 to 2 / 3 of the distance from the top of the cap above the molten steel. First add 8 to 10 kg of exothermic agent to each ingot, and then add another 8 to 10 kg of exothermic agent after at least 30 seconds. After the exothermic agent starts to burn, add 2 to 4 kg of insulation agent.

[0014] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0015] Furthermore, the chemical composition of 0Cr11 steel is C≤0.08%; Si≤1.00%; Mn≤1.00%; P≤0.045%; S≤0.030%; Cr: 10.50%~11.70%; Ni≤0.60%; Ti: 6C~0.75%, and the balance is Fe and unavoidable impurities.

[0016] Furthermore, the heat-generating agent is spread out after being added to avoid being gathered at the edge of the cap.

[0017] Furthermore, the ingot mold is preheated before pouring, and the preheating temperature is 60-120°C.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) By studying the solidification mechanism of ingot shape and molten steel, as well as the influence of factors such as ingot mold, molten steel temperature and pouring speed on ingot defects, the solidification process of molten steel is controlled so that the molten steel presents a solidification order from outside to inside and from bottom to top in the ingot mold; this is because the temperature of the ingot mold is 60-120℃, while the temperature of the molten steel is between 1500-1520℃. When the molten steel is poured into the ingot mold, the temperature drops to about 1400℃. According to the rule that "the greater the temperature drop, the faster the solidification", the molten steel near the inner wall of the ingot mold solidifies first, and the upper part of the ingot can float due to the low density of the high-temperature molten steel. At the same time, the exothermic agent added to the upper part of the ingot can generate lasting heat, and the added heat-insulating agent can prevent the heat from being easily dissipated. The molten steel at the cap mouth will not solidify in a short time, thus forming a solidification order from bottom to top. At the same time, the molten steel at the cap mouth solidifies later than the molten steel in the ingot body, so that the molten steel at the cap mouth is continuously replenished to the ingot body, thereby effectively preventing shrinkage and looseness caused by the solidification and shrinkage of the molten steel, reducing the occurrence of defects such as shrinkage, looseness and cracks, improving the density of the ingot, and ensuring the overall quality of the ingot;

[0020] 2) It can effectively reduce the defects generated during the die casting process, improve the quality of steel ingots, ensure that the quality of products after rolling meets the requirements, improve the flaw detection pass rate of rolled billets, improve the yield rate of the entire line, and solve the difficulties in quality control of the casting process. DETAILED DESCRIPTION

[0021] The die casting process of 0Cr11 steel described in the present invention controls the following process:

[0022] 1) The steel ingot is cast by the mold casting method. The molten steel with qualified composition is poured into the steel ingot mold. The superheat of the mold casting is controlled at 50-60℃;

[0023] 2) The ingot casting time is controlled within 8 to 12 minutes;

[0024] 3) Cap filling time> 6min;

[0025] 4) Add exothermic agent at 1 / 2 to 2 / 3 of the distance from the top of the cap above the molten steel. First add 8 to 10 kg of exothermic agent to each ingot, and then add another 8 to 10 kg of exothermic agent after at least 30 seconds. After the exothermic agent starts to burn, add 2 to 4 kg of insulation agent.

[0026] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0027] Furthermore, the chemical composition of 0Cr11 steel is C≤0.08%; Si≤1.00%; Mn≤1.00%; P≤0.045%; S≤0.030%; Cr: 10.50%~11.70%; Ni≤0.60%; Ti: 6C~0.75%, and the balance is Fe and unavoidable impurities.

[0028] Furthermore, the heat-generating agent is spread out after being added to avoid being gathered at the edge of the cap.

[0029] Furthermore, the ingot mold is preheated before pouring, and the preheating temperature is 60-120°C.

[0030] In order to more intuitively embody the present invention, the embodiments of the present invention are further described in conjunction with the examples. The following examples are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any technical solution that can be obviously obtained by a person skilled in the art within the technical scope disclosed in the present invention, including simple changes or equivalent replacements, is within the protection scope of the present invention.

[0031] [Example 1]

[0032] In this embodiment, the chemical composition of 0Cr11 steel is, by mass percentage, carbon (C): 0.07%; silicon (Si): 1.00%; manganese (Mn): 1.00%; phosphorus (P): 0.035%; sulfur (S): 0.020%; chromium (Cr): 10.50%; nickel (Ni): 0.60%; titanium (Ti): 0.75%; the remainder is iron and unavoidable impurities.

[0033] The die casting process of 0Cr11 described in this embodiment is as follows:

[0034] 1) Use a 2.9t ingot mold and preheat the ingot mold to 110°C before pouring; pour the molten steel with qualified composition into the ingot mold, and control the superheat at 55°C;

[0035] 2) The ingot casting time is controlled within 9 minutes;

[0036] 3) The filling time of the cap mouth is 6 minutes;

[0037] 4) Add the heating agent at 1 / 2 of the top of the cap above the molten steel. First add 9kg of heating agent to each ingot, and then add another 9kg of heating agent after an interval of 40s; spread the heating agent flat after adding to avoid gathering at the edge of the cap; after the heating agent starts to burn, add 3kg of insulation agent;

[0038] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0039] The steel ingot after die casting in this embodiment has a dense structure without defects such as shrinkage cavities, looseness and cracks, and the qualified rate of flaw detection after rolling is 99.2%.

[0040] [Example 2]

[0041] In this embodiment, the chemical composition of 0Cr11 steel is, by mass percentage, carbon (C): 0.06%; silicon (Si): 0.83%; manganese (Mn): 0.57%; phosphorus (P): 0.041%; sulfur (S): 0.024%; chromium (Cr): 11.70%; nickel (Ni): 0.48%; titanium (Ti): 0.59%; the remainder is iron and unavoidable impurities.

[0042] The die casting process of 0Cr11 described in this embodiment is as follows:

[0043] 1) Use a 2.9t ingot mold and preheat it to 80°C before pouring; pour the molten steel with qualified composition into the ingot mold, and control the superheat at 60°C;

[0044] 2) The ingot casting time is controlled within 10 minutes;

[0045] 3) The filling time of the cap mouth is 6min30s;

[0046] 4) Add the heating agent at 1 / 2 of the top of the cap above the molten steel. First add 8kg of heating agent to each ingot, and then add another 8kg of heating agent after an interval of 40s; spread the heating agent flat after adding to avoid gathering at the edge of the cap; after the heating agent starts to burn, add 2.6kg of insulation agent;

[0047] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0048] The steel ingot after die casting in this embodiment has a dense structure without defects such as shrinkage cavities, looseness and cracks, and the qualified rate of flaw detection after rolling is 99.8%.

[0049] [Example 3]

[0050] In this embodiment, the chemical composition of 0Cr11 steel is, by mass percentage, carbon (C): 0.05%; silicon (Si): 0.72%; manganese (Mn): 0.76%; phosphorus (P): 0.028%; sulfur (S): 0.017%; chromium (Cr): 10.69%; nickel (Ni): 0.55%; titanium (Ti): 0.66%; the remainder is iron and unavoidable impurities.

[0051] The die casting process of 0Cr11 described in this embodiment is as follows:

[0052] 1) Use a 2.9t ingot mold and preheat it to 100°C before pouring; pour the molten steel with qualified composition into the ingot mold, and control the superheat at the start of casting at 55°C;

[0053] 2) The ingot casting time is controlled within 9min20s;

[0054] 3) The filling time of the cap mouth is 6min20s;

[0055] 4) Add the heating agent 2 / 3 above the molten steel from the top of the cap. First add 8.5kg of heating agent to each ingot, and then add another 8.5kg of heating agent after 40s. Spread the heating agent flat after adding to avoid gathering at the edge of the cap. After the heating agent starts to burn, add 4kg of insulation agent.

[0056] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0057] The steel ingot after die casting in this embodiment has a dense structure without defects such as shrinkage cavities, looseness and cracks, and the qualified rate of flaw detection after rolling is 99.6%.

[0058] [Example 4]

[0059] In this embodiment, the chemical composition of 0Cr11 steel is, by mass percentage, carbon (C): 0.07%; silicon (Si): 0.93%; manganese (Mn): 0.88%; phosphorus (P): 0.036%; sulfur (S): 0.022%; chromium (Cr): 10.94%; nickel (Ni): 0.41%; titanium (Ti): 0.56%; the remainder is iron and unavoidable impurities.

[0060] The die casting process of 0Cr11 described in this embodiment is as follows:

[0061] 1) Use a 2.9t ingot mold and preheat it to 90°C before pouring; pour the molten steel with qualified composition into the ingot mold, and control the superheat at 57°C;

[0062] 2) The ingot casting time is controlled within 10 minutes;

[0063] 3) The filling time of the cap mouth is 7 minutes;

[0064] 4) Add the heating agent 2 / 3 above the molten steel from the top of the cap. First add 9kg of heating agent to each ingot, and then add another 9kg of heating agent after 40s. Spread the heating agent flat after adding to avoid gathering at the edge of the cap. After the heating agent starts to burn, add 3.5kg of insulation agent.

[0065] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0066] The steel ingot after die casting in this embodiment has a dense structure, without defects such as shrinkage cavities, looseness and cracks, and the qualified rate of flaw detection after rolling is 99.5%.

[0067] [Example 5]

[0068] In this embodiment, the chemical composition of 0Cr11 steel is, by mass percentage, carbon (C): 0.066%; silicon (Si): 0.87%; manganese (Mn): 0.94%; phosphorus (P): 0.035%; sulfur (S): 0.026%; chromium (Cr): 11.32%; nickel (Ni): 0.53%; titanium (Ti): 0.58%; the remainder is iron and unavoidable impurities.

[0069] The die casting process of 0Cr11 described in this embodiment is as follows:

[0070] 1) Use a 2.9t ingot mold and preheat the ingot mold to 70°C before pouring; pour the molten steel with qualified composition into the ingot mold, and control the superheat at 58°C;

[0071] 2) The ingot casting time is controlled within 11min30s;

[0072] 3) The filling time of the cap mouth is 6min40s;

[0073] 4) Add the heating agent at 1 / 2 of the top of the cap above the molten steel. First add 8kg of heating agent to each ingot, and then add another 8kg of heating agent after 1 minute. Spread the heating agent flat after adding to avoid gathering at the edge of the cap. After the heating agent starts to burn, add 2.7kg of insulation agent.

[0074] 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

[0075] The steel ingot after die casting in this embodiment has a dense structure without defects such as shrinkage cavities, looseness and cracks, and the qualified rate of flaw detection after rolling is 99.7%.

[0076] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A die casting process for 0Cr11 steel, characterized in that: Control the following processes: 1) The steel ingot is cast by the mold casting method. The molten steel with qualified composition is poured into the steel ingot mold. The superheat of the mold casting is controlled at 50-60℃; 2) The ingot casting time is controlled within 8 to 12 minutes; 3) Cap filling time> 6min; 4) Add exothermic agent at 1 / 2 to 2 / 3 of the distance from the top of the cap above the molten steel. First add 8 to 10 kg of exothermic agent to each ingot, and then add another 8 to 10 kg of exothermic agent after at least 30 seconds. After the exothermic agent starts to burn, add 2 to 4 kg of insulation agent. 5) When pouring molten steel, an argon gas sealing ring is used to block the air, and asbestos felt is added on the argon gas sealing ring to prevent secondary oxidation.

2. The die casting process of 0Cr11 steel according to claim 1, characterized in that: The chemical composition of 0Cr11 steel is C≤0.08% by mass; Si≤1.00%; Mn≤1.00%; P≤0.045%; S≤0.030%; Cr: 10.50%~11.70%; Ni≤0.60%; Ti: 6C~0.75%, and the balance is Fe and unavoidable impurities.

3. The die casting process of 0Cr11 steel according to claim 1, characterized in that: After the exothermic agent is added, it is spread out to avoid gathering at the edge of the cap.

4. The die casting process of 0Cr11 steel according to claim 1, characterized in that: The ingot mold is preheated before pouring, and the preheating temperature is 60-120℃.