Method for calculating contribution of vanadium and nitrogen elements to strength of screw thread steel

Abstract

The application discloses a method for calculating the strength contribution of vanadium and nitrogen elements to screw steel, and comprises the following steps: S1, calculating the influence of the existing form of vanadium elements in screw steel on the yield strength of screw steel and the contribution to the tensile strength; S2, calculating the influence of the precipitation temperature of vanadium nitride particles on the yield strength increment of screw steel and the influence on the tensile strength of screw steel; S3, calculating the contribution of the precipitated vanadium nitride to the yield strength of screw steel by affecting the grain size and the contribution to the tensile strength of screw steel; and S4, calculating the comprehensive contribution of vanadium and nitrogen elements to the yield strength of screw steel and the comprehensive contribution to the tensile strength of screw steel. The method and system provided by the application restore and describe the principle of the influence of vanadium and nitrogen elements on the strength of screw steel, can effectively improve the accuracy of the judgment of the strength of screw steel, and can improve the success rate of the work of steel grade component design and screw steel performance adjustment.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar. Background Technology

[0002] Currently, over 80% of rebar products in China utilize vanadium microalloying to enhance their strength. Vanadium recovery during steelmaking is relatively stable, and vanadium nitride particles typically precipitate only after the transformation from austenite to ferrite or from austenite to ferrite + pearlite. Fluctuations in rolling temperature have minimal impact on vanadium nitride particle precipitation. Therefore, when the nitrogen content in rebar is stable, the incremental contribution of vanadium to rebar strength is relatively stable. This is why rebar manufacturers prefer to use vanadium to strengthen rebar.

[0003] However, as steel mills have been working to reduce alloy costs, rebar mills have generally adopted processes such as blowing nitrogen into molten steel and adding nitrogen-enhancing agents during the steelmaking process to increase the nitrogen content in the steel. The purpose of this is to promote the precipitation of vanadium in the rebar as vanadium nitride particles. According to production experience, if 0.01% of vanadium in rebar is precipitated as vanadium nitride particles, it can increase the yield strength of the rebar by more than 25 MPa. However, if this 0.01% of vanadium in the rebar exists in the form of vanadium carbide or solid-solution vanadium, it can only increase the yield strength of the rebar by about 10 MPa. The fluctuation of nitrogen content in rebar has a very large impact on the strength performance of rebar.

[0004] Furthermore, the precipitation process of vanadium nitride particles in rebar is very complex. Currently, the methods for calculating the strength increment of rebar by vanadium and nitrogen elements in existing publicly available technologies mainly rely on a simple calculation based on the vanadium content, nitrogen content, and the mass ratio of vanadium to nitrogen in the vanadium nitride molecule (vanadium / nitrogen = 3.64). Existing publicly available technologies consider that if the ratio of vanadium to nitrogen content in rebar is greater than 3.64, then vanadium is in excess, and all nitrogen in the steel precipitates as vanadium nitride particles; if the ratio of vanadium to nitrogen content in rebar is less than 3.64, then nitrogen is in excess, and all vanadium in the steel precipitates as vanadium nitride particles.

[0005] However, existing calculation methods can only qualitatively approximate the contribution of vanadium and nitrogen to the strength of rebar. Their calculation theory does not conform to the following phenomena: "In the actual precipitation process of vanadium nitride particles in rebar, regardless of whether vanadium or nitrogen is in excess, there is no phenomenon of all nitrogen or vanadium particles being precipitated. Some dissolved nitrogen and dissolved vanadium will always remain in the steel; the precipitation temperature of vanadium nitride particles will affect the precipitation strengthening effect. The higher the precipitation temperature, the worse the strengthening effect, and the lower the precipitation temperature, the better the strengthening effect; during the precipitation process of vanadium nitride particles, ferrite grains will be refined, but the refining effect on ferrite grains is not linearly related to the amount of vanadium nitride particles precipitated."

[0006] Therefore, the theoretical approach to calculating the strength increment of vanadium and nitrogen elements in rebar in the existing technology does not match the actual phenomenon. It can only qualitatively approximate the contribution of vanadium and nitrogen elements to the strength of rebar, resulting in poor calculation accuracy and affecting the success rate of steel composition design and rebar strength performance adjustment.

[0007] Therefore, how to effectively calculate the contribution of vanadium and nitrogen to the strength of rebar is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar, so as to improve the accuracy of judging the strength of rebar and thus better apply it to the design of steel composition and performance adjustment.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] A method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar includes the following steps:

[0011] Step S1: Calculate the effect of the form of vanadium in rebar on the yield strength of rebar σ 屈服-V And the effect of tensile strength Rm 抗拉-v ;

[0012] Step S2: Calculate the effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar σ 屈服-温 And its effect on the tensile strength Rm of rebar 抗拉-温 ;

[0013] Step S3: Calculate the contribution σ of precipitated vanadium nitride to the yield strength of rebar by affecting grain size. 屈服-晶 And its contribution to the tensile strength of rebar, Rm 抗拉-晶 ;

[0014] Step S4: Calculate the combined contribution σ of vanadium and nitrogen elements to the yield strength of rebar. 屈服and the comprehensive contribution of Rm to the tensile strength of rebar 抗拉 For example, formulas (1-1) and (1-2):

[0015] σ 屈服 =σ 屈服-V +σ 屈服-温 +σ 屈服-晶 (1-1);

[0016] Rm 抗拉 =Rm 抗拉-V +Rm 抗拉-温 +Rm 抗拉-晶 (1-2).

[0017] Preferably, step S1 includes:

[0018] Through regression analysis of the detection data, based on the total vanadium content ω in rebar... V and total nitrogen content ω N Obtain the parameter value K;

[0019] Based on the parameter value K, and the vanadium content ω precipitated in the rebar in the form of vanadium nitride. V析出 and nitrogen content ω N析出 The proportional relationship between these elements is used to obtain the vanadium content ω in the form of vanadium nitride in rebar. V析出 ;

[0020] According to the vanadium content ω V析出 The influence of the form of vanadium in rebar on the yield strength of rebar was obtained. 屈服-V And the effect of tensile strength Rm 抗拉-v .

[0021] Preferably, step S1 further includes:

[0022] According to the theory that if every 0.01% vanadium in rebar precipitates in the form of vanadium nitride particles, the yield strength Q of the rebar can be increased. 1屈服 and the tensile strength Q of rebar 1抗拉 Furthermore, the 0.01% vanadium in rebar, if not precipitated as vanadium nitride particles, could increase the yield strength Q of the rebar. 2屈服 and the tensile strength Q of rebar 2抗拉 The influence of the form of vanadium in rebar on the yield strength σ of rebar was calculated. 屈服-V And the effect of tensile strength Rm 抗拉-v For example, formulas (2-1) and (2-2):

[0023] σ 屈服_V =Q 1屈服 *ω V析出 *100+Q2屈服 *(ω V -ω V析出 )*100 (2-1);

[0024] Rm 抗拉_V =Q 1抗拉 *ω V析出 *100+Q 2抗拉 *(ω V -ω V析出 )*100 (2-2).

[0025] Preferably, step S1 further includes:

[0026] The mass ratio of vanadium to nitrogen precipitated in the form of vanadium nitride is equal to K1. Based on this rule, the following formula (2-3) is obtained:

[0027]

[0028] Vanadium content ω precipitated in the form of vanadium nitride V析出 In addition to the vanadium content ω that did not precipitate as vanadium nitride V未析出 Equal to the total vanadium content ω in rebar V Based on this rule, we can derive the following formula (2-4):

[0029] ω V析出 +ω V未析出 =ω V (2-4);

[0030] Nitrogen content ω in the form of vanadium nitride N析出 In addition to the nitrogen content ω that is not precipitated in the form of vanadium nitride N未析出 Equal to the total nitrogen content ω in rebar N Based on this rule, we can derive the following formula (2-5):

[0031] ω N析出 +ω N未析出 =ω N (2-5);

[0032] The content of unprecipitated vanadium in rebar ω V未析出 Multiply by the amount of unprecipitated nitrogen ω N未析出 The parameter value related to the total vanadium content and total nitrogen content in rebar is denoted as K. Based on the regression analysis of the test data, formula (2-6) is derived according to this rule:

[0033] ω V未析出 *ω N未析出 =K (2-6);

[0034] Based on formulas (2-3), (2-4), (2-5), and (2-6), the vanadium content ω can be simplified to obtain the vanadium content ω. V析出 The calculation formula.

[0035] Preferably, step S1 further includes:

[0036] The formulas (2-3), (2-4), (2-5), and (2-6) contain a total of ω V析出 ω N析出 ω V未析出 ω N未析出 ω V and ω N There are a total of 6 variables. After solving the simultaneous equations, eliminate ω. V未析出 ω N析出 and ω N未析出 Then, we obtain formula (2-7):

[0037]

[0038] Preferably, based on the detection regression analysis, the parameter value K is given by the following formula:

[0039] K = 0.0059523*(ω V ) 0.315 *(ω N ) 0.9 ;

[0040] Since the molar ratio of vanadium to nitrogen in the molecular structure of vanadium nitride is 1:1, the mass ratio of vanadium to nitrogen precipitated in the form of vanadium nitride is K1 = 3.64.

[0041] The vanadium content ω can be simplified by using the parameter value K. V析出 The calculation formula is (2-8):

[0042]

[0043] Preferably, step S3 includes:

[0044] Based on the vanadium content ω precipitated in the form of vanadium nitride in rebar V析出 The contribution σ of precipitated vanadium nitride to the yield strength of rebar is obtained by influencing the grain size. 屈服-晶 As in formula (4-1):

[0045]

[0046] According to regression analysis of the test data, the contribution of vanadium nitride particles to the tensile strength of rebar by affecting grain size is K, which is the effect on yield strength. 晶 Times, as in formula (4-2):

[0047] Rm 抗拉-晶 =K 晶 *σ 屈服-晶 (4-2).

[0048] Preferably, step S2 includes:

[0049] Based on the relationship between the saturation solubility product of vanadium nitride in ferrite and temperature, and the total vanadium content ω in rebar... V and total nitrogen content ω N The theoretical calculation temperature t at which vanadium nitride particles in rebar begin to saturate and precipitate is obtained.

[0050] Through regression analysis of the detection data, the theoretical temperature t at which vanadium nitride particles begin to saturate and the vanadium content ω in the form of vanadium nitride in the rebar were calculated based on the data. V析出 The effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar was obtained. 屈服-温 And according to σ 屈服-温 The effect of vanadium nitride particle precipitation temperature on the tensile strength Rm of rebar was calculated. 抗拉-温 .

[0051] Preferably, step S2 further includes:

[0052] Based on regression analysis of the test data, the vanadium element content ω in rebar precipitated in the form of vanadium nitride was... V析出 The effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar σ 屈服-温 The relationship between the theoretically calculated temperature t at which vanadium nitride particles begin to saturate and precipitate in rebar is shown in formula (3-1):

[0053]

[0054] The relationship between the saturation solubility product of vanadium nitride in ferrite and temperature is shown in equation (3-2):

[0055]

[0056] Preferably, step S2 further includes:

[0057] Based on formulas (3-1) and (3-2), by simultaneously solving the two equations and eliminating the parameter t, the effect of the precipitation temperature of vanadium nitride particles on the increase in the yield strength of rebar is obtained as σ. 屈服-温 As in formula (3-3):

[0058]

[0059] Based on regression analysis of the test data, the effect of the precipitation temperature of vanadium nitride particles on the tensile strength Rm of rebar was investigated. 抗拉-晶K is the effect on yield strength 温 Times, as in formula (3-4):

[0060] Rm 抗拉-温 =K 温* σ 屈服-温 (3-4)

[0061] The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar provided by this invention includes the following steps: Step S1: Calculate the influence of the existence form of vanadium in rebar on the yield strength σ of rebar. 屈服-V And the effect of tensile strength Rm 抗拉-v Step S2: Calculate the effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar σ 屈服-温 And its effect on the tensile strength Rm of rebar 抗拉-温 Step S3: Calculate the contribution σ of precipitated vanadium nitride to the yield strength of rebar by affecting grain size. 屈服-晶 And its contribution to the tensile strength of rebar, Rm 抗拉-晶 Step S4: Calculate the combined contribution σ of vanadium and nitrogen elements to the yield strength of rebar. 屈服 and the comprehensive contribution of Rm to the tensile strength of rebar 抗拉 The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar provided by this invention systematically restores and describes the principle of how vanadium and nitrogen elements affect the strength of rebar, and derives the influence coefficients based on test data. It calculates the influence of the form of vanadium in rebar on the strength of the rebar, the influence of the precipitation temperature of vanadium nitride particles on the strength of the rebar, and the influence of precipitated vanadium nitride on the strength of the rebar by affecting the grain size. Since the logical calculation process of this application has a good consistency with the precipitation phenomenon of vanadium and nitrogen elements in rebar, it can effectively improve the accuracy of judging the strength of rebar and increase the success rate of steel composition design and rebar performance adjustment. Attached Figure Description

[0062] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0063] Figure 1 This is a flowchart illustrating a specific implementation of the method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar provided by the present invention. Detailed Implementation

[0064] The core of this invention is to provide a method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar, which improves the accuracy of judging the strength of rebar and thus can be better applied to steel composition design and performance adjustment.

[0065] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0066] Please refer to Figure 1 , Figure 1 This is a flowchart illustrating a specific implementation of the method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar provided by the present invention.

[0067] In this embodiment, the method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar is mainly used to calculate the contribution of vanadium and nitrogen elements to the strength of rebar, thereby providing a basis for steel composition design and performance adjustment.

[0068] Includes the following steps:

[0069] Step S1: Calculate the effect of the form of vanadium in rebar on the yield strength of rebar σ 屈服-V And the effect of tensile strength Rm 抗拉-v ;

[0070] Step S2: Calculate the effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar σ 屈服-温 And its effect on the tensile strength Rm of rebar 抗拉-温 ;

[0071] Step S3: Calculate the contribution σ of precipitated vanadium nitride to the yield strength of rebar by affecting grain size. 屈服-晶 And its contribution to the tensile strength of rebar, Rm 抗拉-晶 ;

[0072] Step S4: Calculate the combined contribution σ of vanadium and nitrogen elements to the yield strength of rebar. 屈服 and the comprehensive contribution of Rm to the tensile strength of rebar 抗拉 .

[0073] Specifically, the combined contribution of vanadium and nitrogen elements to the yield strength of rebar, σ 屈服 and the comprehensive contribution of Rm to the tensile strength of rebar 抗拉 For example, formulas (1-1) and (1-2):

[0074] σ 屈服 =σ 屈服-V +σ 屈服-温 +σ 屈服-晶 (1-1);

[0075] Rm抗拉 =Rm 抗拉-V +Rm 抗拉-温 +Rm 抗拉-晶 (1-2).

[0076] Specifically, σ 屈服 Rm 抗拉 These represent the combined contributions (MPa) of vanadium and nitrogen elements in rebar to the yield strength and tensile strength of rebar, respectively; σ 屈服-温 Rm 抗拉-温 The effects of vanadium nitride particle precipitation temperature on the yield strength and tensile strength (MPa) of rebar; σ 屈服-晶 Rm 抗拉-晶 The contributions (MPa) of precipitated vanadium nitride to the yield strength and tensile strength of rebar by affecting grain size are respectively represented; σ 屈服-V Rm 抗拉-v These correspond to the contributions (MPa) of vanadium in rebar to the yield strength and tensile strength of rebar, respectively, without considering the effect of vanadium nitride particle precipitation temperature on the increase in rebar strength and without considering the effect of vanadium nitride particle precipitation on the grain size of rebar.

[0077] The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar provided by this invention systematically restores and describes the principle of how vanadium and nitrogen elements affect the strength of rebar, and regresses the influence coefficients based on test data. It calculates the influence of the form of vanadium in rebar on the strength of the rebar, the influence of the precipitation temperature of vanadium nitride particles on the strength of the rebar, and the influence of precipitated vanadium nitride on the strength of the rebar by affecting the grain size. Since the logical calculation process of this application has a good consistency with the precipitation phenomenon of vanadium and nitrogen elements in rebar, the method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar provided by this application can effectively improve the accuracy of judging the strength of rebar and increase the success rate of steel composition design and rebar performance adjustment.

[0078] In some embodiments, step S1 includes:

[0079] Through regression analysis of the detection data, based on the total vanadium content ω in rebar... V and total nitrogen content ω N Obtain the parameter value K; the content of unprecipitated vanadium in the finished rebar ω V未析出 Multiply by the amount of unprecipitated nitrogen ω N未析出 It equals "a certain value related to the total vanadium content and total nitrogen content in rebar, namely the parameter value K;

[0080] Based on the parameter value K, and the vanadium content ω precipitated in the rebar in the form of vanadium nitride. V析出 and nitrogen content ωN析出 The proportional relationship between these elements is used to obtain the vanadium content ω in the form of vanadium nitride in rebar. V析出 ;

[0081] According to the vanadium content ω V析出 The influence of the form of vanadium in rebar on the yield strength of rebar was obtained. 屈服-V And the effect of tensile strength Rm 抗拉-v .

[0082] Furthermore, step S1 also includes:

[0083] According to the theory that if every 0.01% vanadium in rebar precipitates in the form of vanadium nitride particles, the yield strength Q of the rebar can be increased. 1屈服 and the tensile strength Q of rebar 1抗拉 Furthermore, the 0.01% vanadium in rebar, if not precipitated as vanadium nitride particles, could increase the yield strength Q of the rebar. 2屈服 and the tensile strength Q of rebar 2抗拉 The influence of the form of vanadium in rebar on the yield strength σ of rebar was calculated. 屈服-V And the effect of tensile strength Rm 抗拉-v For example, formulas (2-1) and (2-2):

[0084] σ 屈服_V =Q 1屈服 *ω V析出 *100+Q 2屈服 *(ω V -ω V析出 )*100 (2-1);

[0085] Rm 抗拉_V =Q 1抗拉 *ω V析出 *100+Q 2抗拉 *(ω V -ω V析出 )*100 (2-2).

[0086] Specifically, based on empirical data summarized from actual production, if 0.01% vanadium in rebar precipitates in the form of vanadium nitride particles, it can increase the yield strength Q of the rebar. 1屈服 It has a strength of 27.6 MPa, which can increase the tensile strength Q of rebar. 1抗拉 The pressure is 23.5 MPa; however, if the 0.01% vanadium in the rebar does not precipitate as vanadium nitride particles (but exists as vanadium carbide or dissolved vanadium), it is consistent with the ω of this application. V未析出 If the yield strength Q of the rebar is the same, then only the yield strength Q of the rebar can be increased. 2屈服 With a strength of 10 MPa, it can increase the tensile strength Rm of rebar. 抗拉-vIt is 11.5 MPa.

[0087] Substituting into formulas (2-1) and (2-2), we obtain the following formula:

[0088] σ 屈服_V =27.6*ω V析出 *100+10*(ω V -ω V析出 )*100;

[0089] Rm 抗拉_V =23.5*ω V析出 *100+11.5*(ω V -ω V析出 )*100.

[0090] In some embodiments, step S1 further includes:

[0091] The mass ratio of vanadium to nitrogen precipitated in the form of vanadium nitride is equal to K1. Based on this rule, the following formula (2-3) is obtained:

[0092]

[0093] Vanadium content ω precipitated in the form of vanadium nitride V析出 In addition to the vanadium content ω that did not precipitate as vanadium nitride V未析出 Equal to the total vanadium content ω in rebar V Based on this rule, we can derive the following formula (2-4):

[0094] ω V析出 +ω V未析出 =ω V (2-4);

[0095] Nitrogen content ω in the form of vanadium nitride N析出 In addition to the nitrogen content ω that is not precipitated in the form of vanadium nitride N未析出 Equal to the total nitrogen content ω in rebar N Based on this rule, we can derive the following formula (2-5):

[0096] ω N析出 +ω N未析出 =ω N (2-5);

[0097] The content of unprecipitated vanadium in rebar ω V未析出 Multiply by the amount of unprecipitated nitrogen ω N未析出 The parameter value related to the total vanadium content and total nitrogen content in rebar is denoted as K. Based on the regression analysis of the test data, formula (2-6) is derived according to this rule:

[0098] ωV未析出 *ω N未析出 =K (2-6);

[0099] Based on formulas (2-3), (2-4), (2-5), and (2-6), the vanadium content ω can be simplified to obtain the vanadium content ω. V析出 The calculation formula.

[0100] Furthermore, step S1 also includes:

[0101] The formulas (2-3), (2-4), (2-5), and (2-6) contain a total of ω V析出 ω N析出 ω V未析出 ω N未析出 ω V and ω N There are a total of 6 variables. After solving the simultaneous equations, eliminate ω. V未析出 ω N析出 and ω N未析出 Then, we obtain formula (2-7):

[0102]

[0103] In some implementations, the parameter value K is determined by the following formula based on detection regression analysis:

[0104] K = 0.0059523*(ω V ) 0.315 *(ω N ) 0.9 ;

[0105] Since the molar ratio of vanadium to nitrogen in the molecular structure of vanadium nitride is 1:1, the mass ratio of vanadium to nitrogen precipitated in the form of vanadium nitride is K1 = 3.64.

[0106] Based on the parameter value K and the mass ratio K1 of vanadium and nitrogen precipitated in the form of vanadium nitride, the following formula is derived:

[0107]

[0108] In the above formula, let ω V ω N Since all values ​​are known, the above formula is ω. V析出 Solve the quadratic equation in one variable, and assume that the solution ω is the solution. V析出 If the value is positive, then the vanadium content ω is obtained. V析出 The calculation formula is (2-8):

[0109]

[0110] It should be noted here that ωV析出 and ω N析出 These correspond to the mass percentages (%) of vanadium and nitrogen elements precipitated in the form of vanadium nitride in rebar, respectively; ω V未析出 ω N未析出 These correspond to the mass percentages (%) of vanadium and nitrogen elements in rebar that are not precipitated as vanadium nitride; ω V ω N The corresponding mass percentages (%) of vanadium and nitrogen in rebar; σ 屈服-V Rm 抗拉-v These correspond to the contributions (MPa) of vanadium in rebar to its yield strength and tensile strength, respectively, without considering the effect of vanadium nitride particle precipitation temperature on the increase in rebar strength or the effect of vanadium nitride particle precipitation on the grain size of rebar.

[0111] In some implementations, step S2 includes:

[0112] Based on the relationship between the saturation solubility product of vanadium nitride in ferrite and temperature, and the total vanadium content ω in rebar... V and total nitrogen content ω N The theoretical calculation temperature t at which vanadium nitride particles in rebar begin to saturate and precipitate is obtained.

[0113] Through regression analysis of the detection data, the theoretical temperature t at which vanadium nitride particles begin to saturate and the vanadium content ω in the form of vanadium nitride in the rebar were calculated based on the data. V析出 The effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar was obtained. 屈服-温 And according to σ 屈服-温 The effect of vanadium nitride particle precipitation temperature on the tensile strength Rm of rebar was calculated. 抗拉-温 .

[0114] In some embodiments, step S2 further includes:

[0115] The vanadium content ω in rebar precipitated in the form of vanadium nitride V析出 The effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar σ 屈服-温 The relationship between the theoretically calculated temperature t at which vanadium nitride particles begin to saturate and precipitate in rebar is shown in formula (3-1):

[0116]

[0117] The relationship between the saturation solubility product of vanadium nitride in ferrite and temperature is shown in equation (3-2):

[0118]

[0119] Specifically, the higher the precipitation temperature of vanadium nitride particles, the weaker their strengthening effect on the yield strength increment. That is, the contribution of a unit mass of precipitated vanadium to the yield strength of rebar decreases as the precipitation temperature of vanadium nitride particles increases. Formula (3-1) is obtained based on regression analysis of the test data.

[0120] In some embodiments, step S2 further includes:

[0121] Based on formulas (3-1) and (3-2), by simultaneously solving the two equations and eliminating the parameter t, the effect of the precipitation temperature of vanadium nitride particles on the increase in the yield strength of rebar is obtained as σ. 屈服-温 As in formula (3-3):

[0122]

[0123] Specifically, in formulas (3-2) and (3-3), σ 屈服-温 ω V析出 , t, ω V ω N By combining these five variables into two equations and eliminating the variable 't', we obtain formula (3-3).

[0124] Based on regression analysis of the test data, the effect of the precipitation temperature of vanadium nitride particles on the tensile strength Rm of rebar was investigated. 抗拉-晶 K is the effect on yield strength 温 Times, as in formula (3-4):

[0125] Rm 抗拉-温 =K 温* σ 屈服-温 (3-4)

[0126] In some implementations, K is obtained based on regression analysis of the detection data. 温 =0.85, based on the effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar σ 屈服-温 With coefficient K 温 The effect of vanadium nitride particle precipitation temperature on the tensile strength Rm of rebar was determined. 抗拉-晶 The calculation formula is as follows:

[0127]

[0128] It should be noted that ω V析出 The mass percentage (%) of vanadium precipitated in the form of vanadium nitride in rebar; ω V ω N These correspond to the total mass percentage (%) of vanadium and nitrogen in rebar, respectively; t is the theoretically calculated temperature (°C) at which vanadium nitride particles in the rebar begin to saturate and precipitate in ferrite; σ 屈服-温 Rm抗拉-温 The effects of vanadium nitride particle precipitation temperature on the yield strength and tensile strength of rebar are given in MPa.

[0129] In some implementations, step S3 includes:

[0130] The more vanadium nitride particles precipitated, the more significant its effect on grain refinement; based on the vanadium content ω precipitated in the form of vanadium nitride in rebar... V析出 The contribution σ of precipitated vanadium nitride to the yield strength of rebar is obtained by influencing the grain size. 屈服-晶 As in formula (4-1):

[0131]

[0132] Specifically, based on the data regression analysis, the coefficient K2 = 202.4. Substituting this into formula (4-1), we obtain the following formula:

[0133]

[0134] According to regression analysis of the test data, the contribution of vanadium nitride particles to the tensile strength of rebar by affecting grain size is K, which is the effect on yield strength. 晶 Times, as in formula (4-2):

[0135] Rm 抗拉-晶 =K 晶 *σ 屈服-晶 (4-2).

[0136] In some implementations, K is obtained based on regression analysis of the detection data. 晶 =0.75, based on the contribution σ of precipitated vanadium nitride to the yield strength of rebar by affecting grain size. 屈服-晶 With coefficient K 晶 The following formula is derived:

[0137]

[0138] Specifically, in the middle ω V析出 σ represents the mass percentage (%) of vanadium precipitated in the form of vanadium nitride in rebar; 屈服-晶 Rm 抗拉-晶 The values ​​correspond to the contributions (MPa) of precipitated vanadium nitride to the yield strength and tensile strength of rebar by affecting grain size.

[0139] For example, in Examples 1-10: A steel mill produces rebar with the following vanadium and nitrogen content. The contribution of vanadium and nitrogen to the strength increase of the rebar was calculated according to the formula described in this application. The calculation results are shown in Table 1 below.

[0140] Table 1. Calculated values ​​of the composition of rebar and the contribution of vanadium and nitrogen elements to the increase in rebar strength in Examples 1-10.

[0141]

[0142]

[0143] To explain in detail the method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar as described in this application, the following is a detailed calculation process for the existence form of vanadium in rebar in Example 1, the effect of the precipitation temperature of vanadium nitride particles on the increase in rebar strength, the effect of vanadium nitride precipitates on the strength of rebar by affecting grain size, and the comprehensive contribution of vanadium and nitrogen elements to the strength of rebar. The calculation process for Examples 2-10 is the same as that for Example 1.

[0144] 1. Calculate the form in which vanadium exists in rebar.

[0145]

[0146]

[0147]

[0148]

[0149] ω V析出 =0.0268 (%)

[0150] σ 屈服_v =27.6*ω V析出 *100+10*(ω V -ω V析出 )*100

[0151]

[0152] Rm 抗拉_v =23.5*ω V析出 *100+11.5*(ω V -ω V析出 )*100

[0153] Rm 抗拉_v =23.5*0.0268*100+11.5*(0.035-0.0268)*100=72.39(MPa)

[0154] 2. The effect of vanadium nitride particle precipitation temperature on the strength increase of rebar

[0155]

[0156]

[0157]

[0158]

[0159] σ 屈服_温 =-3.08*4.45974*(0.0268)=-0.37(MPa)

[0160] Rm 抗拉_温 =-0.37 * 0.85 = -0.31 (MPa)

[0161] 3. The effect of vanadium nitride precipitates on the strength of rebar by affecting grain size.

[0162]

[0163]

[0164] Rn 抗拉_晶 =0.75*σ 屈服_晶 =24.85 (MPa)

[0165] 4. The combined contribution of vanadium and nitrogen elements to the strength of rebar

[0166]

[0167] σ 屈服 =82.15-0.37+33.13=114.92(MPa)

[0168] Rm 抗拉 =Rm 抗拉_v +Rm 抗拉_温 +Rm 抗拉_晶

[0169] Rm 抗拉 =72.39-0.31+24.85=96.93(MPa)

[0170] In Table 1 and the above formulas, ω V析出 The mass percentage (%) of vanadium precipitated in the form of vanadium nitride in the corresponding rebar; ω V ω N These correspond to the mass percentage (%) of vanadium and nitrogen in rebar, respectively; t is the theoretically calculated temperature (°C) at which vanadium nitride particles in the rebar begin to saturate and precipitate in ferrite; σ 屈服 Rm 抗拉 These represent the combined contributions (MPa) of vanadium and nitrogen elements in rebar to the yield strength and tensile strength of rebar, respectively; σ 屈服-温 Rm 抗拉-温The effects of vanadium nitride particle precipitation temperature on the yield strength and tensile strength (MPa) of rebar; σ 屈服-晶 Rm 抗拉-晶 The contributions (MPa) of precipitated vanadium nitride to the yield strength and tensile strength of rebar by affecting grain size are respectively represented; σ 屈服-V Rm 抗拉-v These correspond to the contributions (MPa) of vanadium in rebar to the yield strength and tensile strength of rebar, respectively, without considering the effect of vanadium nitride particle precipitation temperature on the increase in rebar strength and without considering the effect of vanadium nitride particle precipitation on the grain size of rebar.

[0171] Examples 11-20

[0172] To verify the accuracy of the method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar described in this application, a company conducted the following experiment: The C, Si, and M nitrogen content of the rebar in Examples 11-20 were similar, but the vanadium and nitrogen content were different. The strength of the rebar in Examples 11-20 was tested, and the actual contribution value of vanadium and nitrogen elements to the strength of the rebar was compared with the calculated contribution value. The mechanical property test results and calculation results are shown in Tables 2 and 3 below.

[0173] As shown in Tables 2 and 3, the actual and calculated contributions of vanadium and nitrogen to the yield strength of rebar are relatively small, with an average difference of only 0.7 MPa. Similarly, the actual and calculated contributions of vanadium and nitrogen to the tensile strength of rebar are also relatively small, with an average difference of only 0.27 MPa. This indicates that the method for calculating the contribution of vanadium and nitrogen to the strength of rebar provided in this application has high accuracy. This is because the technology provided in this application systematically restores and describes the principle by which vanadium and nitrogen affect the strength of rebar, including calculating the "influence of the existence form of vanadium in rebar on the strength of rebar," the "influence of the precipitation temperature of vanadium nitride particles on the strength of rebar," and the "influence of precipitated vanadium nitride on the strength of rebar by affecting grain size." Furthermore, the influence coefficients were regressed based on the test data. The logical calculation process of this application has good consistency with the precipitation phenomenon of vanadium and nitrogen in rebar. Therefore, the method for calculating the contribution of vanadium and nitrogen to the strength of rebar has high accuracy, which is beneficial to the success rate of steel composition design and rebar performance adjustment.

[0174] Table 2. Comparison of actual and calculated values ​​of the contribution of vanadium and nitrogen elements to the yield strength of rebar.

[0175]

[0176] Table 3. Comparison of Actual and Calculated Values ​​of the Contribution of Vanadium and Nitrogen Elements to the Tensile Strength of Rebar

[0177]

[0178] The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar, provided by this invention, has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar, characterized in that, Includes the following steps: Step S1: Calculate the effect of the form of vanadium in rebar on the yield strength of rebar. and its effect on tensile strength ; Step S2: Calculate the effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar. And its impact on the tensile strength of rebar. ; Step S3: Calculate the contribution of precipitated vanadium nitride to the yield strength of rebar by affecting grain size. And its contribution to the tensile strength of rebar. ; Step S4: Calculate the combined contribution of vanadium and nitrogen elements to the yield strength of rebar. and the overall contribution to the tensile strength of rebar For example, formulas (1-1) and (1-2): （1-1）； （1-2）； Step S1 includes: Through regression analysis of the detection data, based on the total vanadium content in rebar... and total nitrogen content Obtain the parameter value K; Based on the parameter value K, and the content of vanadium precipitated in the rebar in the form of vanadium nitride. and nitrogen content The proportional relationship between these elements is used to obtain the vanadium content precipitated in the form of vanadium nitride in rebar. ; Based on vanadium content The influence of the form of vanadium in rebar on the yield strength of rebar was investigated. and its effect on tensile strength ; Step S1 further includes: According to the theory that if every 0.01% vanadium in rebar precipitates in the form of vanadium nitride particles, the yield strength of the rebar can be increased. and tensile strength of rebar Furthermore, the 0.01% vanadium in rebar, if not precipitated as vanadium nitride particles, could increase the yield strength of the rebar. and tensile strength of rebar The influence of the vanadium's presence form in rebar on the yield strength of rebar was calculated. and its effect on tensile strength For example, formulas (2-1) and (2-2): （2-1）； （2-2）。 2. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to claim 1, characterized in that, Step S1 further includes: The mass ratio of vanadium to nitrogen precipitated in the form of vanadium nitride is equal to K1. Based on this rule, the following formula (2-3) is obtained: （2-3）； Vanadium content precipitated in the form of vanadium nitride In addition to the vanadium content not precipitated in the form of vanadium nitride Equal to the total vanadium content in rebar Based on this rule, we can derive the following formula (2-4): （2-4）； Nitrogen content precipitated in the form of vanadium nitride In addition to the nitrogen content not precipitated in the form of vanadium nitride Equal to the total nitrogen content in rebar Based on this rule, we can derive the following formula (2-5): （2-5）； The content of unprecipitated vanadium in rebar Multiply by the amount of unprecipitated nitrogen The parameter value related to the total vanadium content and total nitrogen content in rebar is denoted as K. Based on the regression analysis of the test data, formula (2-6) is derived according to this rule: （2-6）； Based on formulas (2-3), (2-4), (2-5), and (2-6), the vanadium content can be simplified to obtain the vanadium content. The calculation formula.

3. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to claim 2, characterized in that, Step S1 further includes: Formulas (2-3), (2-4), (2-5), and (2-6) contain a total of , , , , and There are a total of 6 variables. After solving the simultaneous equations, eliminate... , and Then, we obtain formula (2-7): （2-7）。 4. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to claim 3, characterized in that, According to the regression analysis, the parameter value K is given by the following formula: ； Since the molar ratio of vanadium to nitrogen in the molecular structure of vanadium nitride is 1:1, the mass ratio of vanadium to nitrogen precipitated in the form of vanadium nitride is K1=3.

64. The vanadium content can be simplified by using the parameter value K. The calculation formula (2-8): （2-8）。 5. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to claim 1, characterized in that, Step S3 includes: Based on the vanadium content precipitated in the form of vanadium nitride in rebar The contribution of precipitated vanadium nitride to the yield strength of rebar is obtained by influencing grain size. As in formula (4-1): （4-1）； According to regression analysis of the test data, the contribution of vanadium nitride particles to the tensile strength of rebar by affecting grain size is K, which is the effect on yield strength. 晶 Times, as in formula (4-2): （4-2）。 6. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to any one of claims 1 to 5, characterized in that, Step S2 includes: Based on the relationship between the saturation solubility product of vanadium nitride in ferrite and temperature, and the total vanadium content in rebar... and total nitrogen content The theoretical calculation temperature t at which vanadium nitride particles in rebar begin to saturate and precipitate is obtained. Through regression analysis of the detection data, the theoretical temperature t at which vanadium nitride particles begin to saturate and vanadium content in the rebar was calculated based on the data. The effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar was obtained. and according to The effect of vanadium nitride particle precipitation temperature on the tensile strength of rebar was calculated. .

7. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to claim 6, characterized in that, Step S2 further includes: Through regression analysis of the detection data, the content of vanadium precipitated in the form of vanadium nitride in rebar was determined. The effect of vanadium nitride particle precipitation temperature on the increase in yield strength of rebar The relationship between the theoretically calculated temperature t at which vanadium nitride particles begin to saturate and precipitate in rebar is shown in formula (3-1): （3-1）； The relationship between the saturation solubility product of vanadium nitride in ferrite and temperature is shown in formula (3-2): （3-2）。 8. The method for calculating the contribution of vanadium and nitrogen elements to the strength of rebar according to claim 7, characterized in that, Step S2 further includes: Based on formulas (3-1) and (3-2), by simultaneously solving the two equations and eliminating the parameter t, the effect of the precipitation temperature of vanadium nitride particles on the increase in the yield strength of rebar is obtained. As shown in formula (3-3): （3-3）； Based on regression analysis of the test data, the effect of vanadium nitride particle precipitation temperature on the tensile strength of rebar was investigated. K is the effect on yield strength 温 Times, as in formula (3-4): （3-4）。

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