Method for evaluating the level of an aluminum melt in-furnace refining process

Abstract

The application discloses a kind of evaluation methods of aluminum melt in-furnace refining process level, including sampling after aluminum melt in-furnace refining, metallographic microscopic detection, using image j software to analyze and calculate the deslagging rate of metallographic photo, according to the deslagging rate evaluation single in-furnace refining process level and according to the rating evaluation in-furnace refining total process level of single in-furnace refining.The application is calculated by metallographic microscope detection, using image j software, and the deslagging rate of single in-furnace refining is accurately calculated, and the data standard of grading evaluation is formulated for in-furnace refining process according to the deslagging rate, the level reached by various product aluminum melt smelting process for aluminum alloy production, especially continuous casting and rolling production, is described in detail, and quantitative reference data is provided for production technicians, which can be used for product production scheme design and for finding reasons when product defects occur.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of molten aluminum smelting and casting, and particularly relates to a method for evaluating the process level of in-furnace refining of molten aluminum. BACKGROUND

[0002] Aluminum alloy is one of the most widely used metal materials, and is widely used in the fields of automobile manufacturing, aerospace, shipbuilding, construction, electrical appliance manufacturing and chemical industry. With the rapid development of industry, the use range of aluminum alloy is becoming wider and wider, and the product quality requirement is becoming higher and higher. As a key process determining the quality of aluminum alloy products, molten aluminum refining can be divided into pre-furnace refining, in-furnace refining and online refining according to the refining position. Due to the technical difficulty and equipment condition limitation, most production lines do not adopt pre-furnace refining. Therefore, for most aluminum alloy production lines, in-furnace refining is the first step, and is an important factor determining the product level of refined molten aluminum. The evaluation of the refining process level of molten aluminum is generally evaluated by product detection, and it is difficult to make quantitative evaluation of each refining link, especially the in-furnace refining process level. SUMMARY

[0003] The purpose of the present application is to provide a method for evaluating the in-furnace refining process level of molten aluminum, to realize quantitative evaluation of the in-furnace refining process level of molten aluminum, and to further accurately design the in-furnace refining process according to the product quality requirement.

[0004] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0005] A method for evaluating the in-furnace refining process level of molten aluminum, comprising the following steps:

[0006] Step 1: sampling after in-furnace refining of molten aluminum:

[0007] According to the process system, sequentially perform first, second, third and fourth molten aluminum refining in the smelting furnace or holding furnace, complete the in-furnace refining, and take two mushroom samples for each refining for inspection;

[0008] Step 2: metallographic microscopic detection:

[0009] The labeled mushroom-like sample is made into a 20x20x20mm block sample, and the sample is polished into a mirror surface on an automatic polishing machine, washed with water and dried with a hair dryer, then the magnification of the microscope is selected to be 200x under the metallographic microscope to observe the inclusion of the polished surface in the aluminum melt, and three observation surfaces are locked to take photos at different positions for each sample; The magnification of the microscope is selected to be 200x, because the non-metallic inclusions in the aluminum melt are easy to remove and the size is more than 10 microns, and the impurities above 20 microns in the unrefined melt are clearly visible under the metallographic microscope, and the magnification of 200x can not only observe the inclusions above 20 microns in size, but also take into account the inclusions below 15 microns in size, which is easy to count and calculate;

[0010] Step three, analyze the metallographic photo using image j software and calculate the deslagging rate:

[0011] (1) Calibration: calibrate the size of the photo according to the actual size;

[0012] (2) Mark the inclusion position: use the different gray values of inclusions and aluminum matrix to automatically count, or manually mark the position of inclusions;

[0013] (3) Calculate the inclusion cross-sectional area: use the software's built-in calculation module to automatically calculate the cross-sectional area occupied by the inclusion;

[0014] (4) Export data: export the data to an Excel table for deslagging rate calculation, the calculation formula is as follows:

[0015]

[0016] Take 15 fields on each 20x20mm sample observation surface to calculate the average value, calculate the deslagging rate of two samples obtained by each refining and then take the average value; Combined with computer statistical analysis technology and software and graphic analysis system, the inclusions are quantitatively evaluated, because the traditional metallographic method uses a metallographic microscope to observe the inclusions in the metallographic phase, the detection accuracy is not high, and the use of computer software image j can quickly detect the size and number of inclusions in the melt, the metallographic photo under 200x is a rectangular picture with a length of about 723μm and a width of about 543μm, and its area is about 391866μm 2 , suitable for analysis with image j software; The inclusion content calculation uses area ratio, and the deslagging rate calculation uses the inclusion content calculation value before and after refining, and the larger the deslagging rate value, the better the refining effect;

[0017] Step four, evaluate the single-furnace refining process level according to the deslagging rate:

[0018] The process level of single in-furnace refining is classified according to the slagging rate, and the rating standards are as follows and shown in Table 1:

[0019] (1) When the slagging rate is greater than or equal to 43% in the first refining, the rating is level one; when the slagging rate is greater than or equal to 39% but less than 43%, the rating is level two; when the slagging rate is greater than or equal to 35% but less than 39%, the rating is level three; and when the slagging rate is less than or equal to 35%, the rating is level four;

[0020] (2) When the slagging rate is greater than or equal to 24% in the second refining, the rating is level one; when the slagging rate is greater than or equal to 21% but less than 24%, the rating is level two; when the slagging rate is greater than or equal to 18% but less than 21%, the rating is level three; and when the slagging rate is less than or equal to 15%, the rating is level four;

[0021] (3) When the slagging rate is greater than or equal to 16% in the third refining, the rating is level one; when the slagging rate is greater than or equal to 12% but less than 16%, the rating is level two; when the slagging rate is greater than or equal to 9% but less than 12%, the rating is level three; and when the slagging rate is less than or equal to 9%, the rating is level four;

[0022] (4) When the slagging rate is greater than or equal to 8% in the fourth refining, the rating is level one; when the slagging rate is greater than or equal to 5% but less than 8%, the rating is level two; when the slagging rate is greater than or equal to 3% but less than 5%, the rating is level three; and when the slagging rate is less than or equal to 3%, the rating is level four;

[0023] In the above standards, level one is the high-quality level, level two is the good level, level three is the general level, and level four is the unqualified level;

[0024]

[0025] Since the slag content in the aluminum melt is continuously reduced with the deepening of in-furnace refining, the slagging rate of single in-furnace refining is also continuously reduced, therefore, corresponding rating standards are set for different refining times, and the slagging rate corresponding to different values;

[0026] Step five, evaluating the total in-furnace refining process level according to the rating of single in-furnace refining:

[0027] The total in-furnace refining process level is classified according to the slagging rate and the rating of single in-furnace refining, and the rating standards are as follows and shown in Table 2:

[0028] (1) When the rating of the current three refining is level one, the total in-furnace refining process level is rated as level one; or when the rating of the first refining is level one, the rating of the second and third refining includes one level one, and the rating of the fourth refining is at least level three, the total in-furnace refining process level is rated as level one;

[0029] (2) When the rating of the first refining is level one, and the rating of the second and third refining is level two, the total in-furnace refining process level is rated as level two; or when the rating of the first refining is level two, and the rating of the second and third refining is level one, the total in-furnace refining process level is rated as level two;

[0030] (3) the current two refining rating is at least two levels, and the third refining is at least three levels, the total process level of the in-furnace refining is rated as three levels;

[0031] (4) the current two refining rating includes one two level and one three level, and the third refining is at least three levels, the total process level of the in-furnace refining is rated as four levels; or the current two refining rating is three levels, and the third refining and the fourth refining are at least two levels, the total process level of the in-furnace refining is rated as four levels;

[0032] (5) the current two refining rating includes one four level, the total process level of the in-furnace refining is rated as five levels;

[0033] In the above-mentioned standard, the first level is a high-quality level, the second level is a good level, the third level is a general level, the fourth level is a qualified level, and the fifth level is unqualified;

[0034]

[0035] The total process level of the in-furnace refining is evaluated by a comprehensive method, the evaluation method is based on the evaluation data and the rating results in step four, so the samples of the in-furnace refining must be detected four times, and the refining after the fourth time of the in-furnace refining is mainly for cooling the cold material to prevent the aluminum melt from overheating, so the evaluation method of the application is only for the first four times of the in-furnace refining.

[0036] In order to further realize the application, the process system in step one includes adding a refining agent, introducing a refining gas, and synchronously starting stirring after the temperature of the aluminum melt is controlled, and the in-furnace refining is completed according to the process parameters.

[0037] In order to further realize the application, the process parameters include a refining temperature, a refining agent and an adding amount thereof, a gas flow, a refining time, a standing time, and a refining times.

[0038] In order to further realize the application, the high-quality level in step five has the conditions for producing double-zero aluminum foil, the second level is a good level and has the conditions for producing single-zero aluminum foil, the third level is a general level and has the conditions for producing ordinary aluminum alloy plate and strip, the fourth level is a qualified level and is used for producing low-end aluminum alloy plate and strip, and the fifth level is unqualified and cannot produce aluminum alloy plate and strip products.

[0039] The beneficial effects of the application compared with the prior art are as follows:

[0040] The technical scheme adopted in the application is that the selected equipment is the equipment owned by most research institutes and enterprise detection departments, and the calculation method is simple and can be understood and applied to production practice by ordinary technical management personnel.

[0041] The application accurately calculates the slagging rate of single furnace refining by metallographic microscope detection and using image j software, and completes the evaluation of the process level of each furnace refining in a grading method according to the slagging rate data, and then completes the comprehensive grading evaluation of the total process of furnace refining according to the process level rating results of single furnace refining.

[0042] The application formulates data standards for grading evaluation of the furnace refining process according to the slagging rate, and makes detailed instructions for the level required to be reached by the aluminum melt smelting process of various products in aluminum alloy production, especially continuous casting and rolling production, thereby providing quantitative reference data for production technicians, which can be used for product production scheme design and for finding reasons when product defects occur. DETAILED DESCRIPTION

[0043] The application will be further described in combination with specific embodiments.

[0044] An evaluation method of the process level of aluminum melt furnace refining, comprising the following steps:

[0045] Step one, sampling after aluminum melt furnace refining:

[0046] According to the process system, namely after controlling the temperature of the aluminum melt, adding a refining agent, introducing a refining gas, simultaneously starting stirring, and sequentially performing first, second, third and fourth aluminum melt refining of the smelting furnace or the holding furnace (stationary furnace) according to the process parameters, the furnace refining is completed, and two mushroom samples are taken for inspection after each refining, wherein the parameters include refining temperature, refining agent and its addition amount, gas flow, refining time, standing time and refining times;

[0047] Step two, metallographic microscopic detection:

[0048] The mushroom sample is made into a block sample of 20x20x20 (unit: mm), and the sample is polished into a mirror surface on an automatic polishing machine, washed with water and dried with a hair dryer, and then the magnification of the microscope is selected to be 200 times under the metallographic microscope, and the inclusion condition of the polished surface in the aluminum melt is observed, and three observation photos are taken at different positions of each sample;

[0049] Step three, using image j software to analyze the metallographic photos and calculating the slagging rate:

[0050] (1) Calibration: calibrate the size of the photo according to the actual size;

[0051] (2) Mark the inclusion position: automatically count using the different gray values of inclusions and aluminum matrix, or manually mark the position where inclusions exist;

[0052] (3) Calculate the inclusion cross-sectional area: automatically calculate the cross-sectional area occupied by the inclusion using the software's built-in calculation module;

[0053] (4) Export data: export the data to an Excel table for slagging rate calculation, with the following formula:

[0054]

[0055] On each 20x20 (unit: mm) sample observation surface, 15 fields of view were evenly taken to calculate the average value. The slagging rate was obtained by averaging the two samples obtained from each refining.

[0056] Step four, evaluate the single furnace refining process level according to the slagging rate:

[0057] The process level of single furnace refining is divided into levels according to the slagging rate, and the evaluation criteria are as follows Table 1:

[0058]

[0059] In the above standard, the first level is high quality, the second level is good, the third level is general, and the fourth level is unqualified;

[0060] Step five, evaluate the total process level of furnace refining according to the evaluation of single furnace refining:

[0061] The slagging rate and rating of single furnace refining are combined to divide the total process level of furnace refining into levels, and the rating criteria are as follows Table 2:

[0062]

[0063] In the above standard, the first level is high quality, which has the conditions to produce double zero aluminum foil; the second level is good, which has the conditions to produce single zero aluminum foil; the third level is general, which has the conditions to produce ordinary aluminum alloy plate and strip; the fourth level is qualified, which is used to produce low-end aluminum alloy plate and strip; the fifth level is unqualified, which cannot produce aluminum alloy plate and strip products.

[0064] Example 1:

[0065] An evaluation method for the process level of aluminum melt furnace refining, comprising the following steps:

[0066] Step one, sampling after aluminum melt furnace refining

[0067] A 8011 aluminum alloy cast-rolled blank production line, the basic parameters of the aluminum melt furnace refining process are: the refining temperature of the smelting furnace is 735±2℃, the refining temperature of the holding furnace is 730±2℃, the Piotrkowski environmental protection refining agent and argon powder refining are used, the smelting furnace is used for the first time and the second refining, the holding furnace is used for the third and fourth refining, the refining agent addition amount of the four times of refining is: 1.2 kg / t.Al, 1.2 kg / t.Al, 0.8 kg / t.Al, 0.5 kg / t.Al, and the refining time of each time is 20 minutes, and the standing time is 20 minutes. After each refining, two mushroom samples are taken, and the samples are marked as 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2 for inspection.

[0068] Step two, metallographic microscopic detection

[0069] The mushroom samples are made into 20×20×20 (unit: mm) block samples, and the samples are polished into mirror surface on the automatic polishing machine, washed with water and dried with a hair dryer; then the magnification of the microscope is selected as 200 times under the metallographic microscope, the inclusion condition of the polished surface in the aluminum melt is observed, and the photos of three observation surfaces of each sample are taken.

[0070] Step three, calculation of deslagging rate

[0071] The image j software is used to analyze the metallographic photos, the cross-sectional area occupied by the inclusions is automatically calculated by using the calculation module of the software, and then the deslagging rate is calculated by using the following formula.

[0072]

[0073] The average value is obtained by taking 15 visual fields on each 20×20 (unit: mm) sample observation surface, and the final deslagging rate is obtained by calculating the average value of two samples obtained in each refining.

[0074] Step four, evaluation of single in-furnace refining process level according to deslagging rate

[0075] The calculation results of the four times of in-furnace refining deslagging rate are: 43.5%, 22.7%, 16.6%, and 5.2%, corresponding to the rating data standard in table 1, the four times of refining are respectively rated as first class, second class, first class, and first class.

[0076] Step five, evaluation of the process level of the total in-furnace refining process

[0077] According to the four times of in-furnace process level, the total in-furnace process level is completed, the rating results of the four times of refining are combined, and the total process rating standard in table 2 is corresponding. The rating result of the total in-furnace process this time is first class, which has the condition to produce double zero foil.

[0078] Example 2:

[0079] An evaluation method of the aluminum melt in-furnace refining process level, comprising the following steps:

[0080] Step one, sampling after aluminum melt in-furnace refining

[0081] An 8011 aluminum alloy cast-rolling blank production line, the basic parameters of the aluminum melt in-furnace refining process are: the refining temperature of the smelting furnace is 735±2℃, the refining temperature of the holding furnace is 728±2℃, Qinghai sodium-free granular refining agent and argon powder refining are used, the smelting furnace is used for the first and second refining, the holding furnace is used for the third and fourth refining, and the adding amounts of the four times of refining are 1.3 kg / t.Al, 0.8 kg / t.Al, 0.5 kg / t.Al and 0 kg (argon+100 kg cold charge) respectively, and the refining time of each time is 20 minutes, and the standing time is 20 minutes. Two mushroom samples are taken after each refining, and the samples are marked as 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1 and 4-2 for inspection.

[0082] Step two, metallographic microscopic detection

[0083] The mushroom samples are made into 20×20×20 (unit: mm) block samples, and the samples are polished into mirror surfaces on an automatic polishing machine, washed with water and dried with a hair dryer; then the magnification of the microscope is selected to be 200 times under the metallographic microscope, the inclusion condition of the polished surface in the aluminum melt is observed, and three observation surfaces of each sample are locked to take photos.

[0084] Step three, calculation of deslagging rate

[0085] The image j software is used to analyze the metallographic photos, the cross-sectional area occupied by the inclusions is automatically calculated by using the calculation module of the software, and then the deslagging rate is calculated by using the following formula.

[0086]

[0087] The average value is obtained by uniformly taking 15 visual fields on each 20×20 (unit: mm) sample observation surface, and the final deslagging rate is obtained by calculating the average value of the two samples obtained in each refining.

[0088] Step four, evaluation of the single in-furnace refining process level according to the deslagging rate

[0089] The calculation results of the four times of in-furnace refining deslagging rate are 43.7%, 21.3%, 15.5% and 3.2%, corresponding to the evaluation data standard in table 1, and the four times of refining are first class, second class, second class and third class respectively.

[0090] Step five, evaluation of the process level of the total in-furnace refining process

[0091] According to the four-time in-furnace process level, the total in-furnace refining process level is rated, and the rating results of the four-time refining are combined to correspond to the total process rating standard in Table 2. The rating result of the total in-furnace refining process is level two, which has the condition to produce single zero foil.

[0092] Example 3:

[0093] An evaluation method of an aluminum melt in-furnace refining process level, comprising the following steps:

[0094] Step one, sampling after aluminum melt in-furnace refining

[0095] A 8011 aluminum alloy cast-rolling stock production line, the basic parameters of the aluminum melt in-furnace refining process are as follows: the refining temperature of the smelting furnace is 732±2℃, the refining temperature of the holding furnace is 726±2℃, Kellyda granular refining agent and argon powder spraying refining are used, the smelting furnace is used for the first and second refining, and the holding furnace is used for the third and fourth refining. The refining agent addition amount of the four-time refining is 1.2kg / t.Al, 0.6kg / t.Al, 0.5kg / t.Al and 0kg (nitrogen+100kg cold charge) respectively. The refining time of each time is 20 minutes, and the standing time is 20 minutes. Two mushroom samples are taken after each refining, and the sample numbers are 1-1, 1-2, 2-1, 2-2, 3-1, 3-2, 4-1 and 4-2 for inspection.

[0096] Step two, metallographic microscopic detection

[0097] The mushroom samples with labels are made into block-shaped samples with a size of 20×20×20 (unit: mm), and the samples are polished into mirror surfaces on an automatic polishing machine. The samples are washed with water and dried by a hair dryer. Then, under a metallographic microscope, the magnification of the microscope is selected to be 200 times, the inclusion condition of the polished surface in the aluminum melt is observed, and three observation faces of each sample are locked to take photos.

[0098] Step three, calculation of deslagging rate

[0099] The image j software is used to analyze the metallographic photos. The cross-sectional area occupied by the inclusions can be automatically calculated by using the calculation module of the software, and then the deslagging rate is calculated by using the following formula.

[0100]

[0101] The average value is obtained by uniformly taking 15 visual fields on each 20×20 (unit: mm) sample observation surface. The final deslagging rate is obtained by calculating the average value of the two samples obtained in each refining.

[0102] Step four, evaluation of single in-furnace refining process level according to deslagging rate

[0103] The calculation results of the four times of in-furnace refining slagging rate are 41.6%, 18.5%, 12.2%, and 2.8%, which correspond to the grading data standards in Table 1, and the four times of refining are secondary, tertiary, secondary, and quaternary, respectively.

[0104] Step five, evaluating the process level of the total in-furnace refining process

[0105] According to the four times of in-furnace process level, the total in-furnace refining process level is graded, and the grading results of the four times of refining are combined, which correspond to the total process grading standards in Table 2. The grading result of the total in-furnace refining process is quaternary, and the aluminum melt in this furnace only meets the requirements of producing low-end aluminum alloy cast and rolled strip.

Claims

1. A method for evaluating the level of in-furnace refining of an aluminum melt, characterized in that Comprising the following steps: Step one, sampling after aluminum melt furnace refining: According to the process system, the first, second, third and fourth aluminum melt refining in the smelting furnace or holding furnace is carried out in turn, and the in-furnace refining is completed. Two mushroom samples are taken for inspection after each refining; Step two, metallographic microscopic detection: The mushroom samples are made into 20x20x20mm block samples, and the samples are polished into mirror surface on the automatic polishing machine. Rinse with water and dry the surface with a hair dryer. Then select the magnification of the microscope under the metallographic microscope to 200 times, observe the inclusion condition of the polished surface in the aluminum melt, and take three observation photos at different positions of each sample; Step three, use image j software to analyze the metallographic photos and calculate the deslagging rate: (1) Calibration: Calibrate the size of the photo according to the actual size; (2) Mark the inclusion position: Use the different gray values of inclusions and aluminum matrix to automatically count, or manually mark the position of inclusions; (3) Calculate the inclusion cross-sectional area: Use the software's built-in calculation module to automatically calculate the cross-sectional area occupied by the inclusion; (4) Export data: Export the data to Excel table for deslagging rate calculation, the calculation formula is as follows: Take 15 fields on each 20x20mm sample observation surface to calculate the average value, and calculate the deslagging rate of two samples obtained in each refining respectively to obtain the average value; Step four, evaluate the single in-furnace refining process level according to the deslagging rate: The process level of single in-furnace refining is divided into levels according to the deslagging rate, and the evaluation standard is as follows: (1) When the deslagging rate is greater than or equal to 43% during the first refining, it is rated as first class, when the deslagging rate is between 39% and 43%, it is rated as second class, when the deslagging rate is between 35% and 39%, it is rated as third class, and when the deslagging rate is less than or equal to 35%, it is rated as fourth class; (2) When the deslagging rate is greater than or equal to 24% during the second refining, it is rated as first class, when the deslagging rate is between 21% and 24%, it is rated as second class, when the deslagging rate is between 18% and 21%, it is rated as third class, and when the deslagging rate is less than or equal to 15%, it is rated as fourth class; (3) When the deslagging rate is greater than or equal to 16% during the third refining, it is rated as first class, when the deslagging rate is between 12% and 16%, it is rated as second class, when the deslagging rate is between 9% and 12%, it is rated as third class, and when the deslagging rate is less than or equal to 9%, it is rated as fourth class; (4) When the deslagging rate is greater than or equal to 8% during the fourth refining, it is rated as first class, when the deslagging rate is between 5% and 8%, it is rated as second class, when the deslagging rate is between 3% and 5%, it is rated as third class, and when the deslagging rate is less than or equal to 3%, it is rated as fourth class; In the above standard, first class is high quality level, second class is good level, third class is general level, and fourth class is unqualified; Step five, evaluate the total in-furnace refining process level according to the rating of single in-furnace refining: The total in-furnace refining process level is divided into levels according to the deslagging rate and rating of single in-furnace refining, and the evaluation standard is as follows: (1) When the current three refining ratings are all first class, the total in-furnace refining process level is rated as first class; or when the first refining rating is first class, the second and third refining ratings include one first class, and the fourth refining rating is at least third class, the total in-furnace refining process level is rated as first class; (2) when the first refining rating is level one, the second and third refining rating is level two, the total process level of the in-furnace refining is rated as level two; or when the first refining rating is level two, the second and third refining rating is level one, the total process level of the in-furnace refining is rated as level two; (3) when the current two refining ratings are at least level two, and the third refining is at least level three, the total process level of the in-furnace refining is rated as level three; (4) when the current two refining ratings include one level two and one level three, and the third refining is at least level three, the total process level of the in-furnace refining is rated as level four; or when the current two refining ratings are both level three, the third and fourth refining is at least level two, the total process level of the in-furnace refining is rated as level four; (5) when the current two refining ratings include one level four, the total process level of the in-furnace refining is rated as level five. In the above standards, level one is high-quality level, level two is good level, level three is general level, level four is qualified level, and level five is unqualified.

2. The method of evaluating the process level of in-furnace refining of aluminum melt according to claim 1, characterized in that: The process system in step one includes controlling the temperature of the aluminum melt, adding a refining agent, introducing a refining gas, and simultaneously starting stirring, and completing the in-furnace refining according to the process parameters.

3. The method of evaluating the process level of in-furnace refining of aluminum melt according to claim 2, characterized in that: The process parameters include the refining temperature, the refining agent and its addition amount, the gas flow, the refining time, the standing time, and the refining times.

4. The method of evaluating the process level of in-furnace refining of aluminum melt according to claim 3, characterized in that: The high-quality level in step five has the condition of producing double-zero aluminum foil; the good level has the condition of producing single-zero aluminum foil; the general level has the condition of producing ordinary aluminum alloy plate and strip; the qualified level is used for producing low-end aluminum alloy plate and strip; and the unqualified level cannot produce aluminum alloy plate and strip products.

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