Low-cost production method of A-series nail-making cold heading steel

Abstract

The invention relates to a low-cost production method of A-series nail-making cold forging steel, which realizes cost reduction and benefit increase by innovative process combination: a ladle external refining technology is used for replacing a traditional LF refining process, so that the refining cost is remarkably reduced, and an aluminum-titanium composite deoxidation process is matched to precisely regulate and control the oxidability of molten steel and greatly improve the purity of the molten steel; a titanium microalloying technology is adopted, so that the titanium element, sulfur, nitrogen and other elements form fine and dispersed Ti4C2S2 and TiN inclusions, the form of the inclusions is effectively improved, austenite grains are refined, and the castability of molten steel is remarkably improved; in combination with an on-line intelligent argon blowing system, argon flow and pressure parameters are dynamically optimized in stages, and the molten steel homogenization effect is enhanced. The process limitation that traditional aluminum-containing cold forging steel must depend on LF refining or vacuum treatment is broken through, under the condition that the LF procedure is omitted, the cold forging steel product meeting the requirements for high purity and fine grains can still be stably produced, and double optimization of the smelting cost and the product quality is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical methods, in particular to a low-cost production method of A-series nail-making cold upsetting steel. BACKGROUND

[0002] Cold upsetting steel is a kind of steel material which is loaded by one or more times of impact at room temperature, and is widely used for producing standard parts such as screws, pins and nuts. The cold upsetting process can save raw materials, reduce cost, and improve the tensile strength of the workpiece and the performance through cold work hardening. The cold upsetting steel must have good cold heading performance. The A-series cold upsetting steel adopts Al deoxidization process, thereby having high plasticity, toughness and good welding performance and cold upsetting performance. However, the current smelting method of the A-series cold upsetting steel is to perform LF refining or double refining process after initial smelting of the molten steel, which has defects such as high power consumption, increased alloy cost and long production cycle, and is difficult to meet the current market demand for low cost and high efficiency. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a low-cost production method of A-series nail-making cold upsetting steel, which can reduce the refining process of the LF furnace, reduce the smelting cost and energy consumption index under the premise of meeting the production rhythm and product quality.

[0004] The technical problem to be solved by the present application is solved by the following technical scheme. The present application is a low-cost production method of A-series nail-making cold upsetting steel. The method replaces the LF refining with the ladle argon station refining, optimizes the top slag material ratio to realize efficient slag washing and gas removal of the molten steel, implements the aluminum-titanium composite deoxidization process, accurately adds the deoxidizer in stages to control the inclusion morphology evolution, combines the titanium micro-alloying refining technology, uses the Ti element to modify the sulfide morphology and refine the austenite grains, applies the online intelligent argon blowing system, dynamically adjusts and controls the argon pressure, flow and soft blowing time parameters according to the molten steel state, performs the short-time static process before continuous casting to ensure the composition uniformity and the tundish castability, and finally controls the main components and weight percentage content of the nail-making cold upsetting steel to C: 0.16-0.18%, Si: 0.03-0.07%, Mn: 0.90-1.00%, P≤0.020%, S≤0.020%, Als: 0.015-0.025%, Ti: 0.015-0.025%, and the balance of Fe and inevitable impurities, thereby realizing the stable production of high-purity and fine-grained cold upsetting steel under the condition of omitting the LF process.

[0005] The technical problem solved by the present application can also be further realized by the following technical solutions, for the low-cost production method of the A-series nail-making cold upsetting steel, in the method, the top slag material ratio refined by the ladle argon station is: calcium-aluminum system pre-melted refining slag 5.0-7.0 kg / t steel, white ash 2.0-4.0 kg / t steel;

[0006] The slag washing and degassing process includes:

[0007] (1) the initial stage argon flow is 300-400 L / min, and lasts for 3-5 minutes;

[0008] (2) the intermediate stage argon flow is reduced to 150-200 L / min, and lasts for 5-8 minutes;

[0009] (3) the final stage argon flow is 80-120 L / min, and the soft blowing time is 3-6 minutes.

[0010] The technical problem solved by the present application can also be further realized by the following technical solutions, for the low-cost production method of the A-series nail-making cold upsetting steel, in the method, the aluminum-titanium composite deoxidization process includes:

[0011] (1) when the steel is discharged from the initial refining furnace, 0.5-0.8 kg / t steel of aluminum-manganese alloy is added to the steel stream to perform pre-deoxidization and generate Al2O3 inclusions;

[0012] (2) after soft blowing for 3 minutes at the argon station, 1.0-1.5 kg / t steel of ferrotitanium is added to control the Ti content to be 0.015-0.025%, so that Ti reacts with residual [O] and [N] to generate TiN;

[0013] (3) aluminum wire is synchronously fed at 0.2-0.3 kg / t steel to adjust Als to 0.015-0.025% to promote the fine and dispersed distribution of TiN;

[0014] (4) through the above sequential control, the erosion of Al2O3 to the stopper and the water gap surface is reduced.

[0015] The technical problem solved by the present application can also be further realized by the following technical solutions, for the low-cost production method of the A-series nail-making cold upsetting steel, in the method, the modification mechanism of titanium micro-alloying refining is:

[0016] (1) Ti combines with N to generate TiN with a particle size ≤5 μm, inhibits the growth of austenite grains, and at the same time consumes [N] in the steel, reducing the brittleness of nitrides;

[0017] (2) Ti forms spindle-shaped Ti4C2S2, improves the distribution form of sulfides, and avoids the cold upsetting cracking caused by chain-like MnS;

[0018] (3) The final molten steel at the end of refining has an oxygen content of not more than 14 ppm and a sulfur content of not more than 0.008%, achieving high cleanliness control.

[0019] The technical problems solved by the present application can also be further achieved by the following technical solutions, for the low-cost production method of A-series nail-making cold-upset steel, in the method, the control parameters of the wire intelligent argon blowing system are:

[0020] The argon constant pressure is 0.3-0.5 MPa, and the flow is adjusted in three stages:

[0021] The strong stirring stage is 300-400 L / min, and lasts for 3-5 minutes;

[0022] The weak stirring stage is 150-200 L / min, and lasts for 5-8 minutes;

[0023] The homogenization stage is 80-120 L / min, and lasts for 3-6 minutes;

[0024] The technical problems solved by the present application can also be further achieved by the following technical solutions, for the low-cost production method of A-series nail-making cold-upset steel, in the method, the static time of the static process after soft blowing is 3-6 minutes.

[0025] 7. The low-cost production method of A-series nail-making cold-upset steel according to claim 1, characterized in that, in the method, the quality verification before continuous casting includes the following indexes:

[0026] (1) The macrostructure segregation grade of the billet is not more than 0.5, and there is no subcutaneous bubble;

[0027] (2) The grain size of the finished rod is 10-11;

[0028] (3) When the 1 / 4 cold-upset upset ratio is not less than 1:3.5, the qualified rate is 100%;

[0029] (4) The superheat degree of the molten steel in the tundish is controlled to be 25-35 DEG C, and the continuous casting speed is 2.0-2.5 m / min.

[0030] Compared with the prior art, the present application has the following advantages:

[0031] 1. The present application realizes precise control of the core process by adopting a low-cost and simplified process flow in the production link through scientific and reasonable process design;

[0032] 2. The present application successfully achieves the ideal deoxidation and alloying effect by using argon station refining technology, with a carefully designed deoxidation process and reasonable regulation of argon flow;

[0033] 3、The present application introduces Ti micro-alloying means, effectively improves the microstructure of steel and inclusion morphology, makes the uniform distribution of structure, and the cold heading performance is excellent;

[0034] 4、The present application precisely controls the micro-alloying and composite deoxidization process, simplifies the process flow, fully meets the requirements of cold heading steel, and achieves the goals of low cost and low energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is the macrograph of the casting blank of the present application example 1;

[0036] Figure 2 It is the macrograph of the casting blank of the present application example 1;

[0037] Figure 3 It is the macrograph of the casting blank of the present application example 2;

[0038] Figure 4 It is the macrograph of the casting blank of the present application example 2;

[0039] Figure 5 It is the macrograph of the casting blank of the present application example 3;

[0040] Figure 6 It is the macrograph of the casting blank of the present application example 3;

[0041] Figure 7 It is the macrograph of the casting blank of the present application example 4;

[0042] Figure 8 It is the macrograph of the casting blank of the present application example 4;

[0043] Figure 9 It is the macrograph of the casting blank of the present application example 5;

[0044] Figure 10 It is the macrograph of the casting blank of the present application example 5;

[0045] Figure 11 It is the macrograph of the casting blank of the present application example 6;

[0046] Figure 12 It is the macrograph of the casting blank of the present application example 6. DETAILED DESCRIPTION

[0047] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0048] Reference Figures 1-12 The present application will be further described below by way of examples.

[0049] Embodiment 1: The specific process of a low-cost A-series steel for cold upsetting and a smelting method thereof is as follows:

[0050] During the converter tapping process, the slag blocking operation is strictly implemented to avoid the inflow of steel slag into the ladle, resulting in secondary oxidation of the molten steel and an increase in the inclusion content. The ladle is subjected to full-bottom argon blowing to realize the homogenization of the composition and temperature of the molten steel and promote the collision, aggregation and floating removal of inclusions. After tapping, 5.0 kg / t of steel of calcium-aluminum-based premelted refining slag and 4.0 kg / t of steel of lime are added to significantly improve the cleanliness of the molten steel and create favorable conditions for the subsequent argon station refining process.

[0051] Ti iron is added 6 minutes before the argon station of the ladle, and the addition amount is 1.3 kg / t of steel. The argon station is continuously subjected to gas stirring to ensure the full diffusion and uniform distribution of titanium elements in the molten steel. The titanium oxide promotes the transformation of brittle spinel inclusions into low-melting titanium aluminate composite phases, and improves the inclusion morphology and size distribution. Titanium, as a strong carbonitride forming element, can generate fine precipitates, effectively pin the austenite grain boundaries to inhibit abnormal grain growth, and improve the grain size and cold upsetting performance of the wire rod.

[0052] Through the synergistic matching of argon constant pressure control and dynamic flow regulation, precise regulation and control of argon supply are realized. The argon constant pressure control is at 0.4 MPa, the flow control is at 200 L / min, the soft blowing time is 9 min, and the soft blowing is followed by a 5 min static process. The residual inclusions are finally separated by using the natural thermal convection of the molten steel.

[0053] Through sampling detection, the cast blank meets the requirements of the detection standard. The low-magnification detection results of this embodiment are shown in Table 2, and the low-magnification pictures are shown in Figure 1 The grain size of the finished wire rod is 10 levels (see Figure 2 , and 1 / 4 cold upsetting is all qualified.

[0054] Embodiment 2: The specific process of a low-cost A-series steel for cold upsetting and a smelting method thereof is as follows:

[0055] The slag blocking operation is strictly implemented in the converter tapping process to avoid the flow of steel slag into the ladle, which leads to the secondary oxidation of the molten steel and the increase of the inclusion content. The whole bottom argon blowing is realized in the ladle to realize the homogenization of the composition and temperature of the molten steel, and to promote the collision, aggregation and floating removal of inclusions. After tapping, 7.0 kg / t of steel of calcium-aluminum premelted refining slag and 2.0 kg / t of steel of lime are added to significantly improve the cleanliness of the molten steel and create favorable conditions for the subsequent argon station refining process.

[0056] Ti iron is added 7 minutes before the argon station of the ladle, and the addition amount is 1.0 kg / t of steel. The continuous gas stirring action of the argon station is used to ensure the full diffusion and uniform distribution of titanium elements in the molten steel. The titanium oxide promotes the transformation of brittle spinel inclusions into low-melting titanium aluminate complex phases, and improves the inclusion morphology and size distribution. Titanium as a strong carbonitride forming element can generate fine precipitates, effectively pinning the austenite grain boundary to inhibit abnormal grain growth, and improving the grain size and cold heading performance of the wire rod.

[0057] Through the synergistic matching of argon constant pressure control and dynamic flow regulation, precise regulation and control of argon supply is realized. The argon constant pressure control is 0.4 MPa, the flow control is 300 L / min, the soft blowing time is 10 min, and the static process is executed for 5 min after the soft blowing is completed. The last floating separation of residual inclusions is completed by using the natural thermal convection of the molten steel.

[0058] Through sampling detection, the casting blank meets the requirements of the detection standard. The low-magnification detection results of this embodiment are shown in Table 2, the low-magnification pictures (selected) are shown in Figure 3 , the grain size of the finished wire rod is 11 (see Figure 4 ), and 1 / 4 cold heading is all qualified.

[0059] In the embodiment 3, a low-cost A series cold heading steel and a smelting method thereof are provided, and the specific process is as follows:

[0060] The slag blocking operation is strictly implemented in the converter tapping process to avoid the flow of steel slag into the ladle, which leads to the secondary oxidation of the molten steel and the increase of the inclusion content. The whole bottom argon blowing is realized in the ladle to realize the homogenization of the composition and temperature of the molten steel, and to promote the collision, aggregation and floating removal of inclusions. After tapping, 7.0 kg / t of steel of calcium-aluminum premelted refining slag and 2.0 kg / t of steel of lime are added to significantly improve the cleanliness of the molten steel and create favorable conditions for the subsequent argon station refining process.

[0061] Ti iron is added 5 minutes before the argon station of the ladle, the addition amount is 1.2 kg / t steel, and the continuous gas stirring action of the argon station is used to ensure the full diffusion and uniform distribution of titanium elements in the molten steel, and the oxides of titanium promote the brittle spinel type inclusions to be converted into low melting point titanium aluminate composite phase, and the inclusion morphology and size distribution are improved; titanium as a strong carbonitride forming element can generate fine precipitates, effectively pinning austenite grain boundaries to inhibit abnormal grain growth, and improving the grain size and cold heading performance of the wire rod.

[0062] Through the synergistic matching of argon constant pressure control and dynamic flow regulation, precise regulation and control of argon supply is realized, the argon constant pressure control is 0.4 MPa, the flow control is 400 L / min, the soft blowing time is 8 min, and after the soft blowing is completed, a 6 min static process is performed, and the last floating separation of residual inclusions is completed by using the natural thermal convection of molten steel.

[0063] Through sampling detection, the casting blank meets the requirements of the detection standard; the macro detection results of this embodiment are shown in Table 2, the macro pictures (selected) are shown in Figure 5 , the grain size of the finished wire rod is 11 (see Figure 6 ), and 1 / 4 cold heading is all qualified.

[0064] In the present embodiment, the specific process of a low-cost A-series steel for cold heading and a smelting method thereof is as follows:

[0065] During the converter tapping process, strict slag blocking operation is implemented to avoid the flow of steel slag into the ladle, resulting in secondary oxidation of the molten steel and an increase in the inclusion content; the ladle is fully bottom-blown with argon to realize the homogenization of the composition and temperature of the molten steel, and promote the collision, aggregation and floating removal of inclusions; after tapping, 6.0 kg / t steel of calcium-aluminum-based premelted refining slag and 3.0 kg / t steel of lime are added, which significantly improves the cleanliness of the molten steel and creates favorable conditions for the subsequent argon station refining process.

[0066] Ti iron is added 5 minutes before the argon station of the ladle, the addition amount is 1.2 kg / t steel, and the continuous gas stirring action of the argon station is used to ensure the full diffusion and uniform distribution of titanium elements in the molten steel, and the oxides of titanium promote the brittle spinel type inclusions to be converted into low melting point titanium aluminate composite phase, and the inclusion morphology and size distribution are improved; titanium as a strong carbonitride forming element can generate fine precipitates, effectively pinning austenite grain boundaries to inhibit abnormal grain growth, and improving the grain size and cold heading performance of the wire rod.

[0067] Through the synergistic matching of argon constant pressure control and dynamic flow regulation, precise regulation and control of argon supply is realized, the argon constant pressure control is 0.4 MPa, the flow control is 400 L / min, the soft blowing time is 8 min, and after the soft blowing is completed, a 6 min static process is performed, and the last floating separation of residual inclusions is completed by using the natural thermal convection of molten steel.

[0068] The sample detection shows that the casting billet meets the detection standard requirements; the macro detection results of this example are shown in Table 2, and the macro pictures (selected) are shown in Figure 7 , the finished wire rod grain size is 10 levels (see Figure 8 ), and 1 / 4 cold upsetting is all qualified.

[0069] Example 5: The specific process of a low-cost A-series steel for cold upsetting and its smelting method is as follows:

[0070] During the converter tapping process, the slag blocking operation is strictly implemented to avoid the flow of steel slag into the ladle, which leads to the secondary oxidation of the molten steel and the increase of the inclusion content. The argon gas is bottom-blown throughout the whole process to realize the homogenization of the composition and temperature of the molten steel, and to promote the collision, aggregation and floating removal of inclusions. After tapping, 7.0 kg / t of steel of calcium-aluminum premelted refining slag and 4.0 kg / t of steel of lime are added to significantly improve the cleanliness of the molten steel and create favorable conditions for the subsequent argon station refining process.

[0071] Ti iron is added 10 minutes before the argon station of the ladle, and the addition amount is 1.1 kg / t of steel. The continuous gas stirring action of the argon station ensures the full diffusion and uniform distribution of titanium elements in the molten steel. The oxides of titanium promote the transformation of brittle spinel inclusions into low-melting titanium aluminate complex phases, which improves the inclusion morphology and size distribution. Titanium, as a strong carbonitride forming element, can generate fine precipitates, effectively pinning the austenite grain boundaries to inhibit abnormal grain growth, and improving the grain size and cold upsetting performance of the wire rod.

[0072] Through the synergistic matching of argon constant pressure control and dynamic flow regulation, precise regulation and control of argon supply are realized. The argon constant pressure control is 0.4 MPa, the flow control is 100 L / min, the soft blowing time is 9 min, and the soft blowing is followed by a 3 min static process. The last floating separation of residual inclusions is completed by the natural thermal convection of the molten steel.

[0073] The sample detection shows that the casting billet meets the detection standard requirements; the macro detection results of this example are shown in Table 2, and the macro pictures (selected) are shown in Figure 9 , the finished wire rod grain size is 10 levels (see Figure 10 ), and 1 / 4 cold upsetting is all qualified.

[0074] Example 6: The specific process of a low-cost A-series steel for cold upsetting and its smelting method is as follows:

[0075] During the converter tapping process, the slag blocking operation is strictly implemented to avoid the flow of steel slag into the ladle, which leads to the secondary oxidation of the molten steel and the increase of the inclusion content. The argon gas is bottom-blown throughout the whole process to realize the homogenization of the composition and temperature of the molten steel, and to promote the collision, aggregation and floating removal of inclusions. After tapping, 7.0 kg / t of steel of calcium-aluminum premelted refining slag and 4.0 kg / t of steel of lime are added to significantly improve the cleanliness of the molten steel and create favorable conditions for the subsequent argon station refining process.

[0076] Ti iron is added 6 minutes before the argon station of the ladle, the amount of addition is 1.4 kg / t steel, and the argon station is used for continuous gas stirring to ensure the full diffusion and uniform distribution of titanium elements in the molten steel. The titanium oxide promotes the transformation of brittle spinel inclusions into low-melting titanium aluminate complex phase, and improves the inclusion morphology and size distribution. Titanium as a strong carbonitride forming element can generate fine precipitates, effectively pinning austenite grain boundaries to inhibit abnormal grain growth, and improving the grain size and cold heading performance of the rod.

[0077] Through the coordinated matching of argon constant pressure control and dynamic flow regulation, precise regulation and control of argon supply is realized. The argon constant pressure control is 0.4 MPa, the flow control is 300 L / min, the soft blowing time is 10 min, and the soft blowing is executed for 4 min after the static process, and the last floating separation of residual inclusions is completed by using the natural heat convection of molten steel.

[0078] Through sampling detection, the casting blank meets the requirements of the detection standard; the macro detection results of the casting blank in the above examples 1-6 are shown in Table 2, and the macro pictures are shown in Figure 11 , the grain size of the finished rod is 11 (see Figure 12 ), and 1 / 4 cold heading is all qualified.

[0079] The chemical composition and weight percentage of the low-cost A series cold heading steel in the above examples 1-6 are shown in Table 1; the macro detection results of the casting blank of the examples 1-6 are shown in Table 2.

[0080] Table 1: Weight percentage of chemical composition in A series cold heading steel of each example (wt%)

[0081]

[0082]

[0083] In Table 1, the balance of chemical composition is Fe and unavoidable impurities.

[0084] Table 2: Macro detection results of casting blank of each example

[0085] Example center porosity centerline segregation internal crack shrinkage cavity subsurface blister non-metallic inclusion 1 0.5 0.5 0 0 0 0 2 0 0.5 0 0 0 0 3 0 0 0 0 0 0 4 0.5 0.5 0 0.5 0 0 5 0.5 0.5 0 0.5 0 0 6 0.5 0.5 0 0 0 0

Claims

1. A low cost production method of A series nail making cold heading steel, characterized by: The method realizes efficient slag washing and degassing of molten steel by adopting ladle argon station refining instead of LF refining and optimizing top slag material ratio; implements aluminum-titanium composite deoxidization process to control inclusion morphological evolution by adding deoxidizers in stages; combines titanium micro-alloying refining technology to modify sulfide form and refine austenite grains by using Ti element; applies online intelligent argon blowing system to dynamically regulate argon pressure, flow and soft blowing time parameters according to the state of molten steel; performs short-time static process before continuous casting to ensure the homogeneity of molten steel composition and ladle castability; finally, the main components and weight percentage content of cold heading steel for nail making are controlled to be C: 0.16-0.18%, Si: 0.03-0.07%, Mn: 0.90-1.00%, P≤0.020%, S≤0.020%, Als: 0.015-0.025%, Ti: 0.015-0.025%, and the balance is Fe and unavoidable impurities, so that stable production of high-purity and fine-grained cold heading steel is realized under the condition of omitting LF process.

2. A low cost production process of A grade nail making cold heading steel as claimed in claim 1, wherein: In the method, the top slag material ratio of the ladle argon station refining is: calcium-aluminum system pre-melted refining slag 5.0-7.0 kg / t steel, white ash 2.0-4.0 kg / t steel; The slag washing and degassing process includes: (1) initial stage argon flow 300-400 L / min, lasting 3-5 minutes; (2) intermediate stage argon flow reduced to 150-200 L / min, lasting 5-8 minutes; (3) final stage argon flow 80-120 L / min, soft blowing time 3-6 minutes.

3. A low cost production process of A grade nail making cold heading steel as claimed in claim 1, wherein: In the method, the aluminum-titanium composite deoxidization process includes: (1) adding aluminum-manganese alloy 0.5-0.8 kg / t steel with the steel stream at the initial refining furnace tapping to pre-deoxidize and generate Al2O3 inclusions; (2) adding ferrotitanium 1.0-1.5 kg / t steel after soft blowing for 3 minutes in the argon station to control Ti content to 0.015-0.025% to make Ti react with residual [O] and [N] to generate TiN; (3) synchronously feeding aluminum wire 0.2-0.3 kg / t steel to adjust Als to 0.015-0.025% to promote fine and dispersed distribution of TiN; (4) reducing the erosion of Al2O3 on the stopper and nozzle surface through the above sequence control.

4. A low cost production process of A grade nail making cold heading steel as claimed in claim 1, wherein: In the method, the modification mechanism of titanium micro-alloying refining is: (1) Ti combines with N to generate TiN with a particle size of ≤5 μm to inhibit the growth of austenite grains, and at the same time, consume [N] in the steel to reduce the brittleness of nitrides; (2) Ti forms spindle-shaped Ti4C2S2 to improve the distribution form of sulfides and avoid cold heading cracking caused by chain-like MnS; (3) the final oxygen content of molten steel is ≤14 ppm, and the sulfur content is ≤0.008%, to realize high-purity control.

5. A low cost production process of A grade nail making cold heading steel as claimed in claim 1, wherein: In the method, the control parameters of the online intelligent argon blowing system are: argon constant pressure 0.3-0.5 MPa, flow adjusted in three stages: strong stirring stage: 300-400 L / min, lasting 3-5 minutes; weak stirring stage: 150-200 L / min, lasting 5-8 minutes; Homogenization stage: 80-120 L / min, for 3-6 minutes.

6. A low cost production process of A grade nail making cold heading steel as claimed in claim 1, wherein: In this method, the static time of the static process after soft blowing is 3-6 minutes.

7. A low cost production process of A grade nail making cold heading steel as claimed in claim 1, wherein: In this method, the quality verification before continuous casting includes the following indexes: (1) The segregation grade of the macrostructure of the casting blank is less than or equal to 0.5, and there is no subcutaneous bubble; (2) The grain size of the finished rod is 10-11; (3) When the 1 / 4 cold upsetting top forging ratio is greater than or equal to 1:3.5, the qualified rate is 100%; (4) The superheat degree of the molten steel in the tundish is controlled at 25-35℃, and the continuous casting speed is 2.0-2.5 m / min.

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