AA TP-1-2012 Standard Test Procedure for Aluminum Alloy Grain Refiners.pdf

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1、Standard Test Procedure for Aluminum Alloy Grain Refiners 2012 ! Aluminum Association No warranty or guarantee of any kind, expressed or implied, by the Aluminum Association or its member companies accompanies this information. Accordingly, the Aluminum Association and its member companies assume no

2、 responsibility or liability for their use whether based on warranty, contract, negligence, strict liability product liability, or otherwise. The use by any member or nonmember of this test procedure is purely voluntary. The Associations publication of this test procedure does not in any respect pre

3、vent or restrict any member or nonmember from manufacturing or supplying products tested under this or any other test procedure. All Aluminum Association published standards, data, specifications and other material are reviewed at least every five years and revised, reaffirmed or withdrawn. Users ar

4、e advised to contact the Aluminum Association to ascertain whether the information in this publication has been superseded in the interim between publication and proposed use. U Copyright 2012. The Aluminum Association. Inc. Unauthorized reproduction and sale by photocopy or any other method is ille

5、gal. Foreword This is the Third Edition of the Standard Test Procedure for Aluminum Alloy Grain Refiners (TP-1). It has been issued after a joint Task Group of The Aluminum Associations Master Alloys and Additives Division and the Technical Committee on Product Standards completed a round robin amon

6、g 13 laboratories to evaluate the repeatability and reproducibility ofTP-1. The detailed findings of that Task Group “Report on the Interpretation of the Precision and Accuracy of the TP-1 Test When Multiple Laboratories Evaluate the Same Grain Refiner“ may be found within the literature ofThe Alumi

7、num Association, and are available on request. The pictures and sketches in this document have been provided by the members of The Aluminum Association. TP-1 Standard Test Procedure f or Aluminum Alloy Grain Refiners i ALUMINUM ASSOCIATION STANDARD TEST PROCEDURE FOR ALUMINUM ALLOY GRAIN REFINERS 1.

8、 Scope This standard procedure is applicable for determining the ability of grain refiners to reduce grain size during solidification of aluminum alloys in specified compositions under standardized conditions, and for examining the structure of the grain refiner for uniformity and freedom from defec

9、ts. This standard is not intended to predict the quantity of grain refiner needed in a specific alloy cast by any casting process or in a specific ingot size. 2. Applicable Specifications and Registration Records 2.1 The following specifications or registration records (the issue in effect on date o

10、f material purchase) form a part of this standard test procedure: The Aluminum Association Registration Record “International Designations and Chemical Composition Limits for Aluminum Hardeners“ (Gray Sheets). OSHA- 1910.1200 Hazard Communication Standard ASTM Standard E34, Test Methods for Chemical

11、 Analysis of Aluminum and Aluminum -Base Alloys, ASTM E88, Practice for Sampling Nonferrous Metals and Alloys in Cast Form for Determination of Chemical Composition, and ASTM El097, Standard Guide for Direct Plasma Emission Spectrometry Analysis. ASTM El12 Estimating the Average Grain Size ASM Handb

12、ook, Volume 9, 2004, Metallography and Microstructures. 3. Sampling 3.1 A sample for chemical analysis shall be taken from a randomly selected waffle ingot or coil of rod for each heat. 3.1.1 For waffle ingot, the sample shall be comprised of drillings from the selected ingot. The drillings shall be

13、 obtained from opposite end segments and one centrally located segment and shall include equal weight of drill chips from top, bottom and middle of ingot. The drillings shall be mixed to form the sample. 3.1.2 For rod, the sample shall consist of milled or clipped chips representative of the full cr

14、oss section from at least two different non-adjacent pieces of rod. 3.2 For grain refining test and metallographic examination, samples shall be selected as follows: 3.2.1 Waffle ingot - one randomly selected waffle ingot from a heat shall represent the heat. The sample for grain size test shall con

15、sist of one piece of the proper weight TP-1 Standard Test Procedure for Aluminum Alloy Grain Refiners I (Section 7.8), including top and bottom surface from the center portion of the ingot (Figure 1). 3.2.2 Rod - a length of rod shall be taken from each end of a coil to represent a heat. The sample

16、for grain size test shall be of the required length, of full cross section to provide the weight required (Section 7.8). For metallographic examination, length of rod sufficient for longitudinal and transverse samples shall be provided (Figure 2). For mechanical property evaluation, a 12“ (300 mm) l

17、ength shall be provided. 4. Chemical Composition 4.1 The grain refiners shall conform to the chemical composition limits shown in Registration Record of Aluminum Association Designations and Chemical Composition for Aluminum Hardeners or the applicable purchase order. 4.2 The samples selected in acc

18、ordance with section 3.1 shall be analyzed in accordance with ASTM Standard E34, Test Methods for Chemical Analysis of Aluminum and Aluminum Base Alloys, ASTM E88, Practice for Sampling Nonferrous Metals and Alloys in Cast F onn for Determination of Chemical Composition, and ASTM E 1097, Standard Gu

19、ide for Direct Plasma Emission Spectrometry Analysis. 5. Grain Size Test Description The Aluminum Association grain refining test procedure can be used to evaluate the performance of grain refiners in rod or waffle ingot form. The test was selected to provide a sample piece with a range of cooling r

20、ates (Figure 3) that would duplicate the cooling rates found in Direct Chill (DC) cast ingots. The cooling rate at the test sample location selected is similar to the cooling rate expected in the center of a 7 inch (180 mm) diameter ingot. 6. Grain Size Test Material Supplies and Equipment 2 6.1 Sup

21、ply of 99.7% pure virgin aluminum that has not been subjected to grain refi ning treatment with the following limits on impurities: Silicon .07% max. Iron .15-.20% Iron to silicon 3 to 4.1 Titanium .005 max. Boron .0005 max. Others each .03 max. Total .10 max. Other aluminum alloys mutually acceptab

22、le may be used. 6.2 Electric resistance furnace capable of maintaining l32510F (7185C) 6.3 Clay-bonded graphite crucible, silicon-carbide crucible or cast-iron crucible, coated with a Dy-Kote to avoid iron contamination; 24 lbs. (ll Kg.) capacity TP-1 Standard Test Procedure for Aluminum Alloy Grain

23、 Refiners 6.4 Calibrated and certified thermocouple and controller indicator capable of measuring temperature up to 1325F (718C) 6.5 Two mold/ladles, coated with graphite spray coated only on the outside (Figure 4) 6.6 Oven for warming the mold/ladles to 600F (316C) 6.7 Sixty minute timer 6.8 Graphi

24、te stirring rod 6.9 Sample tongs 6.10 Quench Tank (Figure 5) 6.11 Protective clothing and face shield 6.12 Notebook 6.13 Water Flowmeter 6.14 Thermometer 7. Procedure for Grain Refiner Test 7.1 Use new crucible or clean, used crucible with a wash heat of the aluminum alloy (Section 6.1). Weigh 22 lb

25、s. (10 Kg.) of the aluminum alloy (Section 6.1), place in crucible, heat to 132510F (7185C) and stabilize. 7.2 Skim dross from surface with minimum disturbance of the liquid metal. 7.3 Place mold/ladles in oven for preheating to 600F (316C). 7.4 Take sample of alloy for confirmation of analysis. 7.5

26、 Turn on water in quench fixture so that water flow rate is one gallon (3.8 liter) per minute. Ifthe waterflow is correct, only the bottom one inch (25 mm) ofthe ladle will be submerged. Record water flow rate and temperature at beginning and end of each test. 7.6 Take sample of the aluminum (Sectio

27、n 6.1) to serve as a control standard for the grain refiner test in accordance with section 7.7. 7.7 Record melt temperature. A preheated mold/ladle is lowered beneath the surface of the melt, held for 30 seconds and withdrawn vertically from the melt to ensure that ladle is filled to the bottom of

28、the notch. The filled ladle is lowered vertically into the retaining ring of the quench tank. 7.8 Add grain refiner alloy to the melt. The remaining metal weight is determined by adjusting the original weight to account for dross and chemical and control standard samples removed. The weight of grain

29、 refiner to be added is determined as follows: TP-1 Standard Test Procedure for Aluminum Alloy Grain Refiners 3 (% Ti or 8 desired) x (Weight of Melt) _ Weight of grain % Ti or 8 in Grain Refiner - refiner to be added The grain refiner alloy is added to the melt at 132510F (7185C) by stirring the al

30、loy into the melt until it has been dissolved (30 seconds). 7.9 For ingot grain refiner, the melt is stirred with the graphite rod for 15 seconds only before the first sample is taken. For rod grain refiner, the melt is stirred with the graphite rod for 15 seconds before each sample is taken. The wa

31、rmed molds/ladles are alternated for each sample taken. Samples are taken as in Section 7.7 above. 7.10 For ingot, samples are taken 30, 60 and 120 minutes after grain refiner sample was added. For rod, samples are taken 2, 5 and 10 minutes after grain refiner sample was added. Other times may be us

32、ed by mutual agreement. The melt temperature is maintained at 132510F (7185C) throughout the test. Each sample shall be identified and a record kept of residence time and melt temperature. 8. Preparation of Samples for Grain Size Measurement 8.1 A transverse section 1.5 (38 mm) from the base (as mea

33、sured along the sloping side) is the standard plane for examination (Figure 6). To obtain this section the following steps are taken: 8.1.1 Measure 1.6“ (40 mm) from the base along the side, cut the sample perpendicular to the axis of the casting. Identify this base section on the side with the samp

34、le number. 8.1.2 Place a mark 1.5 (38 mm) from the base, mount in a lathe and face off to the mark to remove the cut surface. Excess (base) materials may then be cut off and discarded to leave a sample suitable for metallographic preparation usually .5-.6“ (12-15 mm) thick. 8.1.3 The machined surfac

35、e of the sample is lightly ground on 400 grit silicon carbide paper, followed by a 8rasso polishing step, as final preparation prior to etching for grain size evaluation. If lathe facing facilities are not available the cut surface can be brought to the desired plane by grinding on 120 grit silicon

36、carbide paper, followed by grinding on 240 grit silicon carbide paper. The sample is then prepared in the same manner as though it were machined. 8.1.4 For grain size evaluation etch the sample with Poultons Solution1 at room temperature. Warm the grain size sample by holding under running hot water

37、 (120 to 140F) (49 to 60C), then totally immerse in the etch. Usually one immersion of 2-3 seconds duration is satisfactory to produce the desired grain structure. The sample is washed under hot running water after each immersion. As the acid solution ages it may be necessary to increase the number

38、of immersions or the etching ti me. When the desired etch has been achieved the sample is dried. The sample should not be overetched to reveal the cell structure. 1 Poultons Solution: 60% concentrated HCI, 30% concentrated HN03, 5% HF and 5% H20. 4 TP-1 Standard Test Procedure f or Aluminum Alloy Gr

39、ain Refiners 9. Metallographic Grain Size Evaluation 9.1 Grain size evaluation oft he macro-etched sample is achieved using low power magnification comparison with standard samples of known grain sizes (i.e. those determined using the line intercept technique outlined in ASTM E-112 procedure). The c

40、omparison standards should cover the range from 100 to 300 J.Un in 20 J.ll11 increments and from 300 to 500 J.lm in 50 J.lm increments. 9.1.1 Using a 7 to lOx magnification and two side light sources, one fitted with a red filter and the other a green filter, a good grain differentiation is obtained

41、. A further improvement is sometimes obtained by the addition of a blue filter to the objective lens ofthe microscope. 9.1.2 The center 0.5 in. (12 mm) diameter of the test specimen is the only area used in the evaluation. The low power, colored light system yields excellent grain delineation and sh

42、ould be producible within 20 J.lm at 200 J.lm grain size. 10. Acceptability Limit for Grain Size 10.1 The control sample for the 99.7% aluminum (Section 6.1) should be checked, and for test acceptability it should have a grain diameter of 1000 micron or greater. 10.2 The acceptable grain size for ea

43、ch alloy addition rate and residence time shall be established by agreement between the producer and user. 11. Metallographic Examination of Structure 11.1 Specimens shall be prepared from the samples selected in accordance with Section 3.2. 11.1.1 Waffle Ingot 11.1.1.1 Fracture surface - Break sect

44、ion from end of waffle for examination of web area for visible inclusions. 11.1.1.2 30x examination - A full cross section from a position approximately midway between the edge and the center of the ingot shall be cut as shown in Figure 1. The section removed shall be macro polished and examined at

45、30x for macro segregation and hard particles. 11.1.1.3 100 or 200x examination - The sample from section 11.1.1.2 may be examined at 100 or 200x for further definition of segregation or hard particles, if required. 11.1.2 Rod 11.1.2.1 Low magnification examination (30X)- A 4“ (100 mm) long piece sha

46、ll be cut from the rod as shown in Figure 2. The specimen is cut slightly beyond the center of the rod so that after grinding and polishing the center of the rod will be exposed for examination. This cut section is mounted TP-1 Standard Test Procedure for Aluminum Alloy Grain Refiners 5 face down in

47、 epoxy resin and hardener or similar mounting compound following the manufacturers procedure. The mount shall be large enough to allow for hand held grinding and polishing. The specimen may be used for visual examination for macro segregation and presence of foreign particles. 11.1.2.2 High magnific

48、ation examination- A 1“ (25.4 mm) long longitudinal and a transverse specimen shall be sectioned from the rod as shown in Figure 2. This specimen may be used for evaluation of TiAl3 and TiB2 particle size and dispersion and for the presence of foreign particles, i.e. oxides and salts. 11.2 Specimen

49、preparation for metallographic examination of structure. 11.2.1 Low Magnification2 11.2.1.1 Begin preparation of specimen by grinding to a single plane with 80 grit SiC paper using water as a lubricant on a belt sander. 11.2.1.2 Continue grinding with 320 grit SiC paper using water as a lubricant on a Buehler Auto-Met grinding and polishing wheel or similar equipment. 11.2.1.3 Final grinding is on 600 grit paper under conditions outlined in 11.2.1.2. 11.2.1.4 After grinding, polish with levigated Al203 on billiard cloth or similar material un