Judgment method for surfacing process of continuous casting fan-shaped section roller

Abstract

The invention discloses a judgment method for a surfacing process of a continuous casting fan-shaped section roller. The judgment method comprises the following steps: (1) carrying out surfacing operation on the fan-shaped section roller according to an open arc surfacing process; (2) detecting chemical components of a welding surface; (3) predicting the chromium equivalent value Creq, the nickel equivalent value Nieq and the ferrite content delta of the welding surface by adopting the following formulas (I)-(III) according to the detected chemical components; (4) the delta ferrite is compared with the target ferrite, and if the delta ferrite meets the requirements of the target ferrite, the parameters of the open arc welding surfacing process meet the requirements; and if the delta ferrite does not meet the target ferrite requirement, the parameters of the open arc welding surfacing process do not meet the requirement. The method has the advantages that the surfacing quality of the fan-shaped section roller can be predicted, and the prediction result is accurate. According to the method, a reliable basis can be provided for optimization of the surfacing welding process of the fan-shaped section, the product quality is improved, the service life of the fan-shaped section is prolonged, the maintenance cost is reduced, and a guarantee is provided for stable operation of continuous casting; and the service life of surfacing of the continuous casting fan-shaped section roller can be prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of surfacing, in particular to a method for determining a surfacing process of a continuous casting sector roller. Background Art

[0002] The sector rollers of the continuous casting machine are the core equipment. The continuous casting rollers are used in harsh working conditions with high temperature, humidity, strong corrosion and heavy mechanical load. After the sector rollers are welded and put into use online, after a certain amount of steel is passed, defects such as wear, thermal cracks, mechanical cracks and corrosion will occur on the roller surface, resulting in the sector roller gap and arc accuracy deviation exceeding the standard, which needs to be replaced and repaired offline. The service life of the online sector segment is unstable, resulting in the inability to run smoothly and continuously in production, which brings uncertainty to the quality of the ingot, increases production costs and affects the production rhythm. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a method for judging the continuous casting sector roller surfacing process with accurate prediction results.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention includes the following steps: (1) performing surfacing welding operation on the sector roller according to the open arc welding surfacing process;

[0005] (2) Detect the chemical composition of the weld surface;

[0006] (3) using the following formulas (I) to (III) based on the detected chemical composition to predict the chromium equivalent value Creq, nickel equivalent value Nieq and ferrite content δ of the weld surface;

[0007] Creq=a1×Cr+a2×Mo+a3×Si+a4×Nb+a5×Ti+a6×V (Ⅰ);

[0008] Nieq=b1×Ni+b2×C+b3×N+b4×Mn (II);

[0009] δ 铁素体 =d1×(d2×Creq-d3×Nieq-d4) (III);

[0010] Where: Creq is the chromium equivalent value; Cr, Mo, Si, Nb, Ti, V are the mass contents of chromium, molybdenum, silicon, niobium, titanium and vanadium chemical elements respectively; a1, a2, a3, a4, a5, a6 are the coefficients of each item respectively; Nieq is the nickel equivalent value respectively; Ni, C, N, Mn are the mass contents of nickel, carbon, nitrogen and manganese chemical elements respectively; b1, b2, b3, b4 are the coefficients of each item respectively; δ 铁素体 – Ferrite content, %; d1, d2, d3, d4 – coefficients of each item respectively;

[0011] (4)铁素体 Compared with the target ferrite, if δ 铁素体 If the target ferrite requirement is met, then the open arc welding process parameters meet the requirements; if δ 铁素体 If the target ferrite requirement is not met, the open arc welding process parameters do not meet the requirements.

[0012] Furthermore, the parameters of the open arc welding cladding process include preheating temperature T1, interlayer temperature T2, and cooling temperature T3.

[0013] Furthermore, in step (3), the martensite transformation start temperature Ms of the weld surface is calculated using the following formula (IV);

[0014] Ms=c1-(c2×C+c3×Mn+c4×Ni+c5×Cr+c6×Mo) (IV);

[0015] In the formula: Ms is the martensite transformation start temperature, °C; C, Mn, Ni, Cr, Mo are the mass contents of carbon, manganese, nickel, chromium and molybdenum chemical elements respectively; c1, c2, c3, c4, c5, c6 are the coefficients of each item respectively.

[0016] The beneficial effect of adopting the above technical scheme is that: the present invention performs surfacing operation on the sector roller according to the open arc welding surfacing process, performs roller surface chemical composition detection, and then substitutes the result into the corresponding prediction formula, compares the result with the target microstructure martensite and <9% ferrite, and optimizes the corresponding surfacing process according to the deviation, and finally achieves the target result, realizes the prediction and judgment of the sector surfacing quality, prevents the occurrence of continuous casting sector equipment failure, reduces costs, saves manpower, and ensures the stable operation of continuous casting production.

[0017] Compared with the prior art, the present invention has the advantage of being able to predict the quality of the surfacing of the sector rollers, and the prediction result is relatively accurate. Through the present invention, a reliable basis can be provided for the optimization of the surfacing process of the sector, the product quality can be improved, the service life of the sector can be increased, the maintenance cost can be reduced, and the stable operation of the continuous casting can be guaranteed; and the service life of the surfacing of the continuous casting sector rollers can be increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0019] Figure 1 It is a structural schematic diagram of the welding surface detection point described in Example 1 of the present invention.

[0020] In the figure: 1, 2, 3, 4, 5, 6, 7, 8, 9 are all detection points. DETAILED DESCRIPTION

[0021] The judgment method of the continuous casting sector roller surfacing process adopts the following steps:

[0022] (1) The fan-shaped roller is surfacing-welded by open arc welding: the open arc welding surfacing process is formulated according to known data and experience, including preheating temperature T1, interlayer temperature T2, and slow cooling temperature T3; the roller to be surfacing is processed to a certain size, and then the roller is preheated to the preheating temperature T1, and the bottom layer welding wire is 430-O for surfacing, and the interlayer temperature is controlled to T2; then the whole is cooled to the cooling temperature T3, so that the bottom layer austenite is completely transformed into ferrite; then the surface layer welding wire 414-N is used for surfacing, and the interlayer temperature is controlled to T2, and then cooled to the cooling temperature T3 after surfacing; then the last layer is surfacing with 414-N, and finally cooled to room temperature after surfacing.

[0023] (2) Detect the chemical composition of the weld surface: After rough processing of the weld surface, use a spectrometer to detect the composition. It is best to take 5 to 15 test points at equal distances along the length of the roller weld and take the average value.

[0024] (3) using the following formulas (I) to (III) to predict the chromium equivalent value Creq, the nickel equivalent value Nieq and the ferrite content δ according to the detected chemical composition;

[0025] Creq=a1×Cr+a2×Mo+a3×Si+a4×Nb+a5×Ti+a6×V (Ⅰ);

[0026] Nieq=b1×Ni+b2×C+b3×N+b4×Mn (II);

[0027] δ 铁素体 =d1×(d2×Creq-d3×Nieq-d4) (III);

[0028] Where: Creq – chromium equivalent value; Cr, Mo, Si, Nb, Ti, V – are the mass percentages of chemical elements of chromium, molybdenum, silicon, niobium, titanium and vanadium respectively; a1 – coefficient, value 1.0; a2 – coefficient, value 1.0; a3 – coefficient, value 1.5; a4 – coefficient, value 0.5; a5 – coefficient, value 2.0; a6 – coefficient, value 5.0; Nieq – are the nickel equivalent values ​​respectively; Ni, C, N, Mn – are the mass percentages of chemical elements of nickel, carbon, nitrogen and manganese respectively; b1 – coefficient, value 1.0; b2 – coefficient, value 30; b3 – coefficient, value 30; b4 – coefficient, value 0.5; δ 铁素体 – Ferrite content, %; d1 – coefficient, value is 3.0; d2 – coefficient, value is 1.0; d3 – coefficient, value is 0.93; d4 – coefficient, value is 6.7.

[0029] (4) The target ferrite requirement is <9%, and the predicted δ 铁素体 Compared with the target ferrite requirement, the prediction of the quality of the fan-shaped segment cladding is: if δ 铁素体 <9%, it is considered that the preheating temperature T1, interlayer temperature T2, and slow cooling temperature T3 used in step (1) meet the requirements of surfacing and can improve the service life of the surfacing of the continuous casting sector roller; if δ 铁素体 ≥9%, it is considered that the preheating temperature T1, interlayer temperature T2, and slow cooling temperature T3 used in step (1) do not meet the requirements of cladding.

[0030] (5) According to the chemical composition of the weld surface detected in step (2), the martensite start transformation temperature Ms of the weld surface is calculated using the following formula (IV);

[0031] Ms=c1-(c2×C+c3×Mn+c4×Ni+c5×Cr+c6×Mo) (IV);

[0032] Ms – martensite transformation start temperature, ℃; C, Mn, Ni, Cr, Mo – the mass contents of chemical elements such as carbon, manganese, nickel, chromium and molybdenum respectively; c1, c2, c3, c4, c5, c6 – the coefficients of each item respectively.

[0033] In the formula: Ms is the martensite transformation start temperature, ℃; C, Mn, Ni, Cr, Mo are the mass percentages of the chemical elements carbon, manganese, nickel, chromium and molybdenum respectively; c1 is the coefficient, the value is 540; c2 is the coefficient, the value is 497; c3 is the coefficient, the value is 6.3; c4 is the coefficient, the value is 36.3; c5 is the coefficient, the value is 10.8; c6 is the coefficient, the value is 46.6.

[0034] The preheating temperature T1, the interlayer temperature T2 and the slow cooling temperature T3 are modified according to the martensite start transformation temperature Ms, especially in step (4). 铁素体 ≥9%, the correction process is: the preheating temperature T1 and interlayer temperature T2 are to eliminate stress and refine grains, input a certain amount of heat, and avoid the occurrence of hydrogen-induced cracks. The preheating temperature T1 and interlayer temperature T2 values ​​need to be selected and determined according to the martensitic transformation temperature Ms; wherein the preheating temperature T1 < Ms to avoid martensitic transformation during the preheating process; the interlayer temperature T2 > Ms to provide cladding line energy and facilitate the formation of austenite. The slow cooling temperature T3 should be lower than the martensitic end temperature Mf. Generally, Mf is 100°C lower than Ms, that is, the slow cooling temperature T3 < (Ms-100).

[0035] By using this method to judge and improve the preheating temperature T1, the interlayer temperature T2 and the slow cooling temperature T3, the welding life can be improved, and the life of the fan-shaped segment roller can be effectively improved.

[0036] Embodiment: The determination method of the continuous casting sector roller surfacing process is specifically described as follows.

[0037] (1) performing a surfacing operation on the segment roller according to an open arc welding surfacing process, wherein the preheating temperature T1 = 150-200° C., the interlayer temperature T2 = 250-300° C., and the cooling temperature T3 = 100° C.;

[0038] (2) After rough machining the roller surface, select 9 points at equal distances along the length of the roller surface weld, such as Figure 1 At detection points 1, 2, 3, 4, 5, 6, 7, 8 and 9, a spectrometer is used to detect the components and the average value is taken; the detection results are shown in Table 1;

[0039] Table 1: Weld surface inspection results

[0040] Detection point C Mn Si Mo Cr Ni Nb Ti N 1 0.073 0.81 0.51 0.48 12.8 3.2 0.01 0.029 0.045 2 0.081 0.76 0.56 0.44 13.2 3.12 0.009 0.03 0.05 3 0.074 0.73 0.55 0.49 12.9 3.23 0.008 0.031 0.048 4 0.094 0.82 0.49 0.51 13.0 3.4 0.009 0.033 0.05 5 0.086 0.77 0.6 0.5 13.1 2.98 0.008 0.028 0.04 6 0.010 0.75 0.57 0.52 12.9 3.1 0.01 0.03 0.035 7 0.011 0.8 0.54 0.47 12.8 3.21 0.009 0.03 0.044 8 0.095 0.82 0.55 0.44 13.3 2.9 0.009 0.027 0.05 9 0.07 0.81 0.61 0.56 13.2 2.97 0.01 0.027 0.05 average value 0.07 0.79 0.55 0.49 13 3.12 0.009 0.03 0.046

[0041] (3) According to the average value of chemical composition in Table 1, substitute into the corresponding prediction formula (I)-(IV):

[0042] Creq=Cr%+%Mo+1.5%Si+0.5%Nb+2%Ti+5%V=14.38;

[0043] Nieq=Ni%+30%C+30%N+0.5%Mn=6.995;

[0044] Ms=540-(497C+6.3Mn+36.3Ni+10.8Cr+46.6Mo)=223.7℃;

[0045] δ 铁素体 =3×(Creq-0.93Nieq-6.7)=3.52.

[0046] (4) According to the above prediction results, δ ferrite is 3.52%<9%, which shows that the temperature control of the surfacing process in this embodiment is reasonable, the microstructure target is achieved, and the surfacing quality of the fan-shaped tube roller can be improved.

[0047] Statistical case: Before adopting this method, the surfacing life of the continuous casting arc segment sector rollers was an average of 800,000 tons. After adopting this method, the surfacing life of the continuous casting arc segment rollers was an average of 1.1 million tons. It can be seen that the use of this method can effectively ensure that the microstructure of the weld meets the requirements and significantly improve the service life of the weld.

Claims

1. A method for determining the surfacing process of continuous casting segment rollers, characterized in that: The steps include: (1) performing cladding operation on the segment roller by using an open arc welding cladding process; (2) Detect the chemical composition of the weld surface; (3) using the following formulas (I) to (III) based on the detected chemical composition to predict the chromium equivalent value Creq, nickel equivalent value Nieq and ferrite content δ of the weld surface; Creq=a1×Cr+a2×Mo+a3×Si+a4×Nb+a5×Ti+a6×V (Ⅰ); Nieq=b1×Ni+b2×C+b3×N+b4×Mn (II); d 铁素体 =d1×(d2×Creq-d3×Nieq-d4) (Ⅲ); Where: Creq is the chromium equivalent value; Cr, Mo, Si, Nb, Ti, V are the mass contents of chromium, molybdenum, silicon, niobium, titanium and vanadium chemical elements respectively; a1, a2, a3, a4, a5, a6 are the coefficients of each item respectively; Nieq is the nickel equivalent value respectively; Ni, C, N, Mn are the mass contents of nickel, carbon, nitrogen and manganese chemical elements respectively; b1, b2, b3, b4 are the coefficients of each item respectively; δ 铁素体 – Ferrite content, %; d1, d2, d3, d4 – coefficients of each item respectively; (4) 铁素体 Compared with the target ferrite, if δ 铁素体 If the target ferrite requirement is met, then the open arc welding process parameters meet the requirements; if δ 铁素体 If the target ferrite requirement is not met, the open arc welding process parameters do not meet the requirements.

2. The method for determining the continuous casting segment roller surfacing process according to claim 1, characterized in that: The parameters of the open arc welding cladding process include preheating temperature T1, interlayer temperature T2, and cooling temperature T3.

3. The method for determining the continuous casting segment roller surfacing process according to claim 1 or 2, characterized in that: In the step (3), the martensite transformation start temperature Ms of the weld surface is calculated by the following formula (IV); Ms=c1-(c2×C+c3×Mn+c4×Ni+c5×Cr+c6×Mo) (IV); In the formula: Ms is the martensite transformation start temperature, °C; C, Mn, Ni, Cr, Mo are the mass contents of carbon, manganese, nickel, chromium and molybdenum chemical elements respectively; c1, c2, c3, c4, c5, c6 are the coefficients of each item respectively.

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