Method for controlling head-tail reverse deformation defects of thin gauge martensitic wear-resistant steel after quenching

Abstract

A method for controlling head-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching, belonging to the field of steel production. The wear-resistant steel is obtained by completing the quenching cooling process through a roller bottom heating furnace and a roller quenching machine. The deformation defect control method comprises the following steps: plate shape flatness measurement, plate shape defect feature calculation, plate shape defect feature determination, plate shape process parameter debugging for head-tail reverse deformation defect feature quantity, plate shape process parameter debugging for middle transverse bending deformation, and detection and determination of the flatness feature after debugging. The method effectively solves the problem of process parameter adjustment of head-tail reverse deformation defects of thin-gauge high-strength wear-resistant steel plate after quenching caused by complex and variable actual working conditions, such as environmental water temperature, temperature change, heating furnace combustion temperature change, and quenching machine pinch roller wear, etc., and improves the effectiveness of plate shape process parameter setting, plate shape qualification rate, and production efficiency of the production line.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high-strength steel quenching, and particularly relates to a control method for improving head-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching. BACKGROUND

[0002] With the continuous development and improvement of China's industrial technology, the overall demand for medium plates in the shipbuilding industry, mechanical processing industry, petrochemical industry, bridge construction and other industries is increasing, and the demand for high-grade high-strength steel plates is also increasing.

[0003] The production of high-grade high-strength quenched and tempered wear-resistant steel is mainly obtained by using roller hearth heating furnaces and roller quenching machines. Quenching process is an important process for producing high-strength quenched and tempered wear-resistant steel, and the parameters are generally set manually by operators. In the actual production process, the changes of daily environmental temperature, cooling water temperature, cooling water pressure and heating furnace combustion condition affect the setting of the parameters, resulting in various complex flatness defects of the thin-gauge steel plate after quenching. In the quenching production process of thin-gauge martensitic wear-resistant steel, head-tail reverse deformation is a common plate shape defect, which is mainly characterized by the reverse deformation of the head and tail of the steel plate, that is, the head is upturned and the tail is down, or the head is down and the tail is up; the middle part of the steel plate may be coupled with a certain transverse bend or reverse transverse bend on the basis of the head-tail reverse deformation defect. At present, there is no clear way to determine and debug the process parameters for this defect, which seriously affects the plate shape of the subsequent production of thin-gauge steel plates, reduces the yield and qualification rate, affects the production and delivery rhythm and the use of downstream customers, and causes certain economic losses. SUMMARY

[0004] The present application overcomes the shortcomings of the prior art and provides a control method for improving head-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching. Specifically, the method comprises the following steps: measuring the flatness of the plate shape, calculating and determining the plate shape defect characteristics, debugging the plate shape process parameters according to the head-tail reverse deformation defect characteristics, debugging the plate shape process parameters according to the transverse bend deformation of the middle part, and measuring and calculating the flatness characteristics of the plate shape after debugging. By measuring and calculating the deformation characteristics of different regions of the thin-gauge martensitic wear-resistant steel after quenching, and adjusting the corresponding process parameters, the plate shape quality is effectively optimized.

[0005] A control method for head-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching, the thin-gauge martensitic wear-resistant steel is obtained by using a roller hearth heating furnace and a roller quenching machine to complete the quenching and cooling process, and the control method comprises the following steps:

[0006] (1) measuring the flatness of the plate shape;

[0007] (2) calculating the plate shape defect characteristics;

[0008] (3) Plate shape defect feature determination;

[0009] (4) Plate shape process parameter debugging for head-tail reverse deformation defects of steel plate;

[0010] (5) Plate shape process parameter debugging for middle transverse bending deformation of steel plate;

[0011] (6) Measurement and calculation determination of flatness of the plate after debugging.

[0012] Further, in step (1), during the flatness measurement, 12 measurement positions are set at the four corners and the middle of the steel plate, respectively marked as measurement points 1-12 (see Figure 1 ); first, place the ruler at the corresponding edge or middle of the steel plate, then insert the caliper into the gap between the ruler and the upper surface of the steel plate to read the corresponding position of the caliper h 1A ,

[0013] h 1B , etc. (see Figure 2 , Figure 3 ).

[0014] Further, the plate shape data recorded in step (1) are calculated for defect features:

[0015] 1) Calculate the upward or downward amplitude of the head and tail of the steel plate, i.e. the comprehensive deformation amplitude Δh 头 and Δh 尾 ; the specific calculation method is (see Figure 4 ):

[0016] Take measurement point 1 as an example, the calculation method of the deformation amplitude Δh1 at point 1 is:

[0017] Δh1=h 1A -h 1B

[0018] Similarly, Δh2, Δh3, Δh4, and Δh5 are calculated accordingly;

[0019] Calculate the head comprehensive deformation amplitude Δh 头

[0020]

[0021] Similarly, the comprehensive deformation amplitude Δh 尾 of the tail is calculated.

[0022] 2) Calculate the feature quantity w of the middle transverse bending defect (see Figure 5 ):

[0023]

[0024] Further, defect feature judgment is performed on the defect feature value calculated in step (2):

[0025] 1) If the comprehensive deformation amplitude Δh 头 >0 and Δh 尾 <0, it is judged that the head-tail defect of the plate shape is head down and tail up;

[0026] 2) If the comprehensive deformation amplitude Δh 头 <0 and Δh 尾 >0, it is judged that the head-tail defect of the plate shape is head up and tail down;

[0027] 3) Other cases are non-head-tail reverse deformation defects, and other plate shape control methods are used for regulation.

[0028] Further, the plate shape process parameter adjustment for the head-tail reverse deformation defect of the thin gauge steel plate: the defect feature of the reverse deformation of the head and tail of the steel plate is that the residual water amount on the upper surface of the head and tail is different during the cooling process of the steel plate due to the improper adjustment of the roll gap parameter of the roller quenching machine. A higher roll gap setting will cause the cooling water to accumulate on the upper surface of the head of the steel plate through the gap between the steel plate and the pinch roll, and relatively the cooling water on the upper surface of the tail of the steel plate will be reduced (see Figure 6 ); Therefore, the cooling rate on the upper surface of the part with more accumulated cooling water is larger, and the plate shape feature of local transverse bending down is appeared; and the cooling rate on the upper surface of the part with less cooling water is smaller, and the plate shape feature of local reverse transverse bending up is appeared. The adjustment method is to adjust the roll gap of the quenching machine; if the head of the steel plate is down and the tail is up, it indicates that the cooling rate on the upper surface of the head is large and the cooling rate on the upper surface of the tail is small, so it is necessary to reduce the residual cooling water on the upper surface of the head and appropriately increase the cooling water on the upper surface of the tail. The roll gap f set in the original quenching machine can be reduced, and vice versa. The head-tail reverse deformation difference r is calculated:

[0029]

[0030] The roll gap adjustment improvement utility value k=0.3 for the head-tail reverse deformation difference can be obtained through actual production; the actual meaning of k is that for the thin gauge martensitic quenched steel, 1 mm of head-tail reverse deformation difference needs to be improved, the roll gap of the quenching machine needs to be adjusted by 0.3 amplitude; therefore, the roll gap height of the quenching machine needs to be adjusted by kxr, and the adjusted roll gap of the quenching machine is f-0.3r.

[0031] Further, the plate shape process parameter adjustment for the middle part transverse bending defect characteristic of the steel plate: the transverse bending characteristic in the middle part of the steel plate is caused by the improper adjustment of the cooling water ratio parameters on the upper and lower surfaces of the roller quenching machine, which leads to the different cooling rates of the upper and lower surfaces in the thickness direction during the cooling process of the steel plate, resulting in the transverse bending on the side with the faster cooling rate. The adjustment method is to adjust the cooling water ratio of the upper and lower surfaces. If the middle part transverse bending characteristic w is positive, that is, the transverse bending occurs on the upper surface of the steel plate, it indicates that the cooling rate of the upper surface is large and the cooling rate of the lower surface is small, so it is necessary to increase the cooling water ratio b of the original lower surface. The function relationship between the water ratio adjustment improvement utility value a and the thickness d of the steel plate can be obtained through actual production: a = 0.002d - 0.011; the actual meaning of a is that for a steel plate with a thickness of d mm, to improve the transverse bending defect by 1 mm, the cooling water ratio needs to be adjusted by a magnitude; therefore, the cooling water ratio needs to be adjusted by a × w magnitude here, and the adjusted cooling water ratio is b + (0.002d - 0.011) × w.

[0032] Further, after completing the process parameter setting, the plate shape flatness of the newly discharged steel plate is measured again.

[0033] Further, after completing the plate shape measurement of the newly discharged steel plate, the plate shape defect characteristic calculation is performed on the recorded plate shape data of the newly discharged steel plate.

[0034] Further, the plate shape standard judgment is performed on the defect characteristic value calculated in step (6):

[0035] 1) If the comprehensive deformation amplitudes Δh 头 ≧0 and Δh 尾 ≧0 of the head and tail parts of the steel plate are respectively, it can be judged that the plate shape defect is head-tail downward buckling, and thus the control of the head-tail reverse deformation defect of the steel plate is completed.

[0036] 2) If the comprehensive deformation amplitudes Δh 头 ≦0 and Δh 尾 ≦0 of the head and tail parts of the steel plate are respectively, it can be judged that the plate shape defect is head-tail upward buckling, and thus the control of the head-tail reverse deformation defect of the steel plate is completed.

[0037] 3) If the parameter conditions do not meet the judgment conditions 1) or 2), it is judged that the steel plate has head-tail reverse deformation, and returns to the defect characteristic judgment of step (3) to perform a new round of process parameter adjustment process.

[0038] Thus, the control of the head-tail reverse deformation defect of the quenched thin-gauge martensitic wear-resistant steel is completed.

[0039] By the method, the process parameter adjustment problem of the head and tail reverse deformation defects of the thin-gauge high-strength wear-resistant steel plate caused by various factors such as the complex and changeable actual working conditions, for example, the environmental water temperature, the temperature change, the heating furnace combustion temperature change and the quenching machine pinch roll wear, is effectively solved, and the effectiveness of the plate shape process parameter setting, the plate shape qualified rate and the production efficiency of the production line are improved.

[0040] By adopting the application, the head and tail reverse deformation difference of the quenched thin-gauge high-strength wear-resistant steel can be controlled within 1mm, the middle transverse bending is controlled to the minimum level, the plate shape problem of the head and tail reverse deformation in production is improved, the qualified rate and the production efficiency are improved, and the economic loss of the enterprise caused by the non-standard plate shape problem is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A schematic diagram of a steel plate flatness measurement position,

[0042] Figure 2 A schematic diagram of a plug gauge measurement,

[0043] Figure 3 A schematic diagram of a ruler placement and plug gauge measurement position,

[0044] Figure 4 A schematic diagram of head and tail reverse deformation defect calculation,

[0045] Figure 5 A schematic diagram of middle transverse bending defect calculation,

[0046] Figure 6 Influence of roll gap on residual water on the upper surface of the steel plate

[0047] Figure 7 Actual measured plate shape data,

[0048] Figure 8 Plate shape data of a newly cast steel plate,

[0049] Figure 9 Process flowchart of the application. DETAILED DESCRIPTION

[0050] The application will be further described below in combination with specific embodiments:

[0051] The measurement data of a piece of d=10mm thickness specification NM400 martensite steel plate in the production process of the heat treatment production line of a certain factory are shown in the attached table 1. Figure 7 The current process parameter setting is that the lower surface water ratio is b=1.3, and the roll gap is 18mm. 1. Defect feature calculation is performed on the obtained plate shape data:

[0052] (1) Calculate the comprehensive deformation amplitude Δh of the head and tail of the steel plate respectively 头 and Δh 尾

[0053] The deformation amplitude Δh1 at 1 is:

[0054] Δh1 = h 1A -h 1B = 5

[0055] Similarly, Δh2 = 3, Δh3 = 6, Δh4 = 3, Δh5 = 5 are calculated accordingly;

[0056] The comprehensive deformation amplitude Δh of the head is calculated: 头

[0057]

[0058] The comprehensive deformation amplitude Δh of the tail is calculated accordingly: 尾 = -2;

[0059] (2) Calculate the characteristic quantity w of the middle transverse bend defect:

[0060]

[0061] 2. Defect characteristic judgment is carried out for the calculated defect characteristic value:

[0062] Since the comprehensive deformation amplitude Δh of the head of the steel plate 头 > 0, and the comprehensive deformation amplitude Δh of the tail of the steel plate 尾 < 0, it can be judged that the head and tail defects of the plate shape are head down and tail up;

[0063] 3. Plate shape process parameter debugging for the head and tail reverse deformation defects:

[0064] Calculate the difference of head and tail reverse deformation: The roll gap adjustment improvement utility value k = 0.3 for the difference of head and tail reverse deformation, here the quenching machine roll gap height needs to be adjusted by an amplitude of k x r = 0.96, and the adjusted quenching machine roll gap is f - 0.3 r = 17.04;

[0065] 4. Plate shape process parameter debugging for the characteristic quantity of the middle transverse bend defect of the steel plate:

[0066] The middle transverse bend characteristic quantity w is positive, that is, the upper surface of the steel plate appears transverse bend, indicating that the cooling rate of the upper surface is large and the cooling rate of the lower surface is small, so the cooling water ratio of the original lower surface needs to be increased. The water ratio adjustment improvement utility value a = 0.002d - 0.01 = 0.01. Therefore, the adjusted cooling water ratio here is b + a x w = 1.32;

[0067] 5. After completing the process parameter setting, the plate shape of the newly discharged steel plate is measured again, and the plate shape measurement data as shown in the attached Figure 8 is obtained;

[0068] 6. The recorded new rolled steel plate shape data is calculated for the same defect characteristics as in step 2; and the following is obtained

[0069] Δh 头 = 1.6, Δh 尾 = 1.6

[0070] 7. The calculated defect characteristic values are subjected to plate shape standard determination:

[0071] Δh 头 > 0, Δh 尾 > 0, so it is determined that the head and tail of the plate are slightly buckled, and the head buckling and tail warping plate shape defect is improved, and thus the head-tail reverse deformation defect of the 10mm-thick NM400 martensitic wear-resistant steel plate after quenching is completed.

[0072] The above describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for controlling head-to-tail reverse deformation defects in thin-gauge martensitic wear-resistant steel after quenching, characterized in that: The thin-gauge martensitic wear-resistant steel is obtained by a quenching and cooling process using a roller hearth heating furnace and a roller quenching machine. The control method comprises the following steps: (1) Plate flatness measurement: In the plate flatness measurement link, 12 measurement positions are set at the four corners and the middle of the steel plate, marked as measurement points 1 to 12 respectively; first, place the ruler at the corresponding edge or middle measurement position of the steel plate, then insert the feeler gauge into the gap between the ruler and the upper surface of the steel plate to read the reading of the feeler gauge at the corresponding position h 1A 、h 1B ; (2) Calculation of plate shape defect characteristics; 1) Calculation of the upward or downward bending amplitude of the head and tail of the steel plate, that is, the comprehensive deformation amplitude Δh 头 and Δh 尾 The specific calculation method is: Taking measurement point 1 as an example, the deformation amplitude Δh1 at 1 is calculated as follows: Δh1=h 1A -h 1B Similarly, Δh2, Δh3, Δh4, and Δh5 are calculated accordingly; Calculate the comprehensive deformation amplitude of the head Δh 头 Similarly, the comprehensive deformation amplitude Δh of the tail is calculated 尾 ; 2) Calculate the characteristic value w of the middle transverse bending defect: (3) Determination of plate shape defect characteristics; 1) If the comprehensive deformation amplitude Δh of the head and tail of the steel plate 头 >0 and Δh 尾 <0, it can be determined that the plate head and tail defects are head buckled down and tail upturned; 2) If the comprehensive deformation amplitude Δh of the head and tail of the steel plate 头 <0 and Δh 尾 >0, it can be determined that the plate head and tail defects are head upturned and tail buckled; 3) Other cases are non-head-tail reverse deformation defects, and other plate shape control methods are used for control; (4) Debugging of plate shape process parameters for the reverse deformation defect of the head and tail of the steel plate; (5) Debugging of plate shape process parameters for transverse bending deformation in the middle of the steel plate; (6) Measurement and calculation of plate flatness characteristics after debugging.

2. The method for controlling head-to-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching according to claim 1, characterized in that: Debugging of plate shape process parameters for the reverse deformation defect of the head and tail of thin-gauge steel plates: The defect characteristic of reverse deformation at the head and tail of the steel plate is due to improper adjustment of the roller gap parameters of the roller quenching machine, which leads to different residual water amounts on the upper surface of the head and tail of the steel plate during cooling. A high roller gap setting will cause cooling water to pass through the gap between the steel plate and the pinch rollers and accumulate on the surface of the plate head, which will in turn lead to less cooling water on the upper surface of the plate tail. As a result, the upper surface of the area with more cooling water accumulation will have a higher cooling rate, resulting in a plate shape characteristic of local transverse bending and buckling; while the upper surface of the area with less cooling water will have a lower cooling rate, resulting in a plate shape characteristic of local reverse transverse bending and upturning. The adjustment method is to debug the quenching machine roll gap. If the head of the steel plate is buckled down and the tail is tilted up, it means that the cooling rate of the upper surface of the head is high and the cooling rate of the upper surface of the tail is low. Therefore, it is necessary to reduce the residual cooling water on the upper surface of the head and appropriately increase the cooling water on the upper surface of the tail. The roll gap f set by the original quenching machine can be reduced, and vice versa. Calculate the head-tail reverse deformation difference r: Through actual production, the improvement effect value of the roll gap adjustment for the head-to-tail reverse deformation difference can be obtained as k=0.3; the actual meaning of k is that for thin-gauge martensitic quenched steel, to improve the head-to-tail reverse deformation difference of 1mm, the quenching machine roll gap needs to be adjusted by 0.3; therefore, the quenching machine roll gap height needs to be adjusted by an amplitude of k×r, and the adjusted quenching machine roll gap is f-0.3r.

3. The method for controlling head-to-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching according to claim 1, characterized in that: Debugging of plate shape process parameters for the characteristic quantity of transverse bow defect in the middle of the steel plate: The transverse bow feature in the middle of the steel plate is caused by improper adjustment of the cooling water ratio parameters of the upper and lower surfaces of the roller quenching machine, which leads to asynchronous cooling rates of the upper and lower surfaces in the thickness direction of the steel plate during cooling, resulting in transverse bow on the side with a faster cooling rate; the adjustment method is to debug the cooling water ratio of the upper and lower surfaces; if the characteristic quantity w of the transverse bow in the middle is positive, that is, transverse bow occurs on the upper surface of the steel plate, indicating that the cooling rate of the upper surface is large and the cooling rate of the lower surface is small, so it is necessary to increase the original cooling water ratio b of the lower surface; through actual production, it can be obtained that the water ratio adjustment improvement utility value a and the steel plate thickness d satisfy the functional relationship: a=0.002d-0.011; the actual meaning of a is that for a steel plate with a thickness of d mm, to improve the transverse bow defect of 1 mm, the cooling water ratio needs to be adjusted by a range of a; therefore, the cooling water ratio needs to be adjusted by a×w, and the adjusted cooling water ratio is b+(0.002d-0.011)×w.

4. The method for controlling head-to-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching according to claim 1, characterized in that: After completing the process parameter setting, the flatness of the newly-baked steel plate is measured again.

5. The method for controlling head-to-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching according to claim 1, characterized in that: After the shape measurement of the freshly-baked steel plate is completed, shape defect characteristics of the recorded freshly-baked steel plate shape data are calculated.

6. The method for controlling head-to-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching according to claim 1, characterized in that: Determine the defect characteristic value calculated in step (6): 1) If the comprehensive deformation amplitude Δh of the head and tail of the steel plate 头 ≧0 and Δh 尾 ≧0, the plate shape defect can be determined to be head-tail buckling, thus completing the control of the head-tail reverse deformation defect of the steel plate; 2) If the comprehensive deformation amplitude Δh of the head and tail of the steel plate 头 ≦0 and Δh 尾 ≦0, the plate shape defect can be determined as head-tail upturned, thus completing the control of the head-tail reverse deformation defect of the steel plate; 3) If the parameter situation does not meet the judgment condition 1) or 2), it is determined that the steel plate is deformed in the reverse direction of the head and tail, and the process returns to the defect feature judgment of step (3) and a new round of process parameter debugging process is carried out; At this point, the control of head-to-tail reverse deformation defects of thin-gauge martensitic wear-resistant steel after quenching is completed.

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