SAE AMS 2315G-2013 Determination of Delta Ferrite Content《铁素体含量测定》.pdf

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1、_ SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising there

2、from, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2012 SAE International All rights reserved. No part of this publication m

3、ay be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: +1 724-776-4970 (outside U

4、SA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/AMS2315G AEROSPACE MATERIAL SPECIFICATION AMS2315 REV. G Issued 1963-01 Revised 2013-02 Super

5、seding AMS2315F Determination of Delta Ferrite Content RATIONALE AMS2315G revises the requirement for heat treatment of the specimen used to evaluate delta ferrite (3.1.4.1) and introduces alternative etching procedures (3.1.6, 8.4), and is a Five Year Review and update of this specification. 1. SCO

6、PE This specification covers two methods for determining the percentage of delta ferrite in steels and other iron alloys. When applicable, this specification will be invoked by the material specification. 2. APPLICABLE DOCUMENTS The issue of the following documents in effect on the date of the purch

7、ase order forms a part of this specification to the extent specified herein. The supplier may work to a subsequent revision of a document unless a specific document issue is specified. When the referenced document has been cancelled and no superseding document has been specified, the last published

8、issue of that document shall apply. 2.1 ASTM Publications Available from ASTM International, 100 Barr Harbor Drive, P.O. Box C700, West Conshohocken, PA 19428-2959, Tel: 610-832-9585, www.astm.org. ASTM E 3 Preparation of Metallographic Specimens 3. TECHNICAL REQUIREMENTS 3.1 Specimen Preparation 3.

9、1.1 Heat Qualification Sampling shall be in accordance with 4.3.1. Samples shall be converted into test specimens in accordance with 3.1.3. 3.1.2 Product Qualification Product from a heat not qualified, based on sampling as in 4.3.1, shall be sampled in accordance with 4.3.2. Samples shall be conver

10、ted into test specimens in accordance with 3.1.3. SAE AMS2315G Page 2 of 7 3.1.3 Specimen Selection Samples of sufficient size to provide specimens having approximately 0.25 to 0.5 square inch (161 to 323 mm2) prepared surface area or of an area sufficient to randomly select the required number of f

11、ields to accurately examine the sample, shall be cut from the product as in 3.1.3.1, 3.1.3.2, or 3.1.3.3, as applicable. Each specimen shall be marked in such a manner that its orientation with respect to the direction of rolling, drawing, or extruding is easily identifiable. 3.1.3.1 Round, Hexagona

12、l, or Square Product Specimens shall be selected from an area midway between the edge and the center of the sample. 3.1.3.2 Rectangular Product Specimens shall be selected from an area midway between the longitudinal edge and the center of the sample. 3.1.3.3 Tubing and Other Hollow Shapes Specimens

13、 shall be selected from samples which include the full wall thickness of the product. 3.1.4 Heat Treatment Specimens, except as specified in 3.1.4.1, shall be austenitized at the normal recommended temperature for the grade of steel being examined and adequately quenched. The quenched specimens shal

14、l be tempered at a sufficiently high temperature to develop good metallographic contrast. 3.1.4.1 Solution and precipitation hardenable steels shall be solution heat treated and may be precipitation heat treated to develop good metallographic contrast. 3.1.5 Polishing After heat treatment as in 3.1.

15、4, a face of each specimen, perpendicular to the direction of maximum deformation, shall be ground and polished, using standard metallographic polishing techniques in accordance with ASTM E 3 to produce a surface suitable for microscopic examination. 3.1.6 Etching The polished surface of each specim

16、en shall be suitably etched to reveal delta ferrite (See 8.4). 3.2 Procedure for limited delta ferrite criterion Inspect the specimen surface at a magnification appropriate to observe the relative amount and distribution of delta ferrite present. If it is evident that many fields to be measured will

17、 have zero value, and no single field will have a value exceeding the material specification maximum, then measure a set number of fields defined in a laboratory procedure sufficient to ensure that the upper control limit of the mean is less than 50% of the material specification maximum at the 95%

18、confidence level as in 3.2.1 or 3.2.2. A 10% relative accuracy level is not required. In case of dispute over the percentage of delta ferrite, the value determined as in 3.2.1 shall govern. 3.2.1 Point Count Method 3.2.1.1 Field Measurement Project the image of the microstructure of each specimen on

19、to the ground-glass screen of a reflection-type microscope or metallograph. Place a transparent point-counting grid template either in front of or behind the ground glass. The template should consist of either 100 or 500 systematically spaced grid points, either in the form of fine crosses or a grid

20、 lattice. The magnification chosen should be high enough to clearly resolve the delta ferrite grains but not so high that the number of grid points falling in the ferrite grains exceeds one, on the average. For each specimen, count the number of grid points (i.e., the intersection point of the cross

21、es or grid blocks) that fall within the ferrite grains as one and those that fall on the phase boundaries as one-half. SAE AMS2315G Page 3 of 7 3.2.1.2 Field Selection Select the fields to be measured randomly, that is, without looking at the image, by moving the stage controls. Do not alter the pos

22、ition so that grid points fall on or miss ferrite grains. Space the fields selected around the specimen surface in a systematic pattern. Measure a sufficient number of fields so that the relative accuracy (See 3.2.1.3.5) is 10% or less. The relative accuracy of the measurement is influenced by the v

23、olume fraction of the ferrite, the magnification, the grid point density, the number of fields measured, and the field-to-field variation of the ferrite phase. 3.2.1.3 Calculation 3.2.1.3.1 Ferrite per Field Calculate the volume fraction of ferrite using Equation 1 for each field measured. V i,P i,P

24、t-100=(Eq. 1) where: V,i= Volume fraction of ferrite in % of each field P,i = Number of grid points in the ferrite phase or on the phase boundaries Pt= Number of grid points 3.2.1.3.2 Ferrite per Specimen Determine the mean value of the volume fraction of ferrite using Equation 2. VV i,n-=(Eq. 2) wh

25、ere: V= Mean volume fraction of ferrite per specimen n = Number of fields measured in the specimen 3.2.1.3.3 Calculate the standard deviation of the field-to-field variation of the volume fraction of ferrite using Equation 3. s V i,V( )2n 1- 1 2=(Eq. 3) where: s = Standard deviation of the volume fr

26、action measurements SAE AMS2315G Page 4 of 7 3.2.1.3.4 Calculate the 95% confidence limit (95% CI) of the volume fraction measurements using Equation 4. 95% CI 2.0sn( )1 2-=(Eq. 4) where: 2.0 is given as the “t“ multiplier for purposes of simplicity. If desired, the exact “t“ value for any value can

27、 be used instead of 2. Values for t, as a function of n, for a 95% confidence interval are tabulated in most statistical textbooks. 3.2.1.3.5 Calculate the percent relative accuracy (% RA) of the volume fraction measurement using Equation 5, if required (See 3.2). % RA95% CIV-100=(Eq. 5) 3.2.1.3.5.1

28、 A 10% relative accuracy is adequate. If the calculated % RA is substantially higher, use the following formula to estimate the number of fields (n) required to obtain a 10% RA: n20sV- 2=(Eq. 6) 3.2.1.3.6 Express the results as the volume fraction, V the 95% CI and indicate the % RA; e.g., V 95% CI

29、(% RA)(Eq. 7) Unless criterion of 3.2 for limited delta ferrite is met, in which case express result as V 95% Cl without % RA. 3.2.2 Image Analysis Method Each specimen shall be etched so that only the ferrite phase is darkened preferentially, or everything but the ferrite phase is darkened preferen

30、tially. Choose a magnification on the image analysis monitor that permits accurate detection of the ferrite grains. Adjust the threshold setting to detect only the ferrite grains, using an appropriate method such as alternating between the live and the detected images (“flicker mode“). Use automatic

31、 stage movement, if available, to select the fields to be measured without bias. If such a system is not available, select the fields by moving the stage controls without viewing the image. Space the fields to be measured systematically around the specimen surface. Measure the ferrite volume fractio

32、n by dividing the number of detected picture points per field by the total number of picture points per field and express this value as a percentage. Automatic percentage readout may be used according to the equipment manufacturers instructions. Measure enough fields per specimen so that the relativ

33、e accuracy is 10% or less, unless the limited delta ferrite criterion of 3.2 is met. 3.2.2.1 Calculation Calculate the volume fraction per field, as described in 3.2.2, and the mean volume fraction of ferrite, the standard deviation, the 95% confidence level, and the % relative accuracy, if required

34、, as described in 3.2.1.3. Express the test results in the same manner as described in 3.2.1.3 as content of delta ferrite. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection The vendor of the product shall supply all samples for vendors tests and shall be responsible for the performa

35、nce of all required tests. Purchaser reserves the right to sample and to perform any confirmatory testing deemed necessary to ensure that the product conforms to specified requirements. SAE AMS2315G Page 5 of 7 4.2 Classification of Tests All applicable requirements are acceptance tests and shall be

36、 performed to represent each lot. 4.2.1 Heat Qualification Conformance to “heat qualification“ requirements on samples as in 4.3.1, if acceptable, need be conducted only once per heat. 4.2.1.1 Heats which have been qualified as semi-finished product shall be considered qualified for finished product

37、. 4.2.2 Product Qualification Tests on product not “heat qualified“ shall be conducted on product from each lot. 4.3 Sampling The sampling procedure described in 4.3.1 shall be performed by the producer for heat qualification. No further sampling by the producer shall be required from a heat which m

38、eets the requirements of the applicable material specification. Sampling procedure on product which lacks ingot or strand traceability shall be as described in 4.3.2. 4.3.1 Heat Qualification 4.3.1.1 Heats of Top-Poured Ingots Samples shall be taken from semi-finished or finished product representin

39、g the top and bottom of the first ingot and last usable ingot from heats having not more than 10 ingots or not over 30 tons (27 216 kg) or from portions of heats within these limits; and from the top and bottom of the first, middle, and last usable ingot of heats having more than 10 ingots or over 3

40、0 tons (27 216 kg). 4.3.1.2 Heats of Bottom-Poured Ingots Samples shall be taken from semi-finished or finished product representing the top and bottom of three ingots. One ingot shall be taken at random from the first usable plate poured, one ingot at random from the usable plate poured nearest to

41、the middle of the heat, and one ingot at random from the last usable plate poured. When a heat is constituted by two usable plates, one ingot shall be taken at random from each plate. When a heat consists of a single usable plate, any three random ingots may be selected. 4.3.1.2.1 If there are less

42、than 3 ingots in the heat, samples shall be taken representing the top and bottom of all ingots. 4.3.1.3 Strand-Cast Heats Samples shall be taken from semi-finished or finished product having at least a 3:1 reduction in cross-section from the cast strand (or samples of the cast strand similarly redu

43、ced) representing the front, middle, and back of both strands when two strands are cast, or of an inside strand and an outside strand when more than two strands are cast. When a single strand is cast, 6 samples having at least a 3:1 reduction from the cast strand (or samples of the cast strand simil

44、arly reduced) representing both ends of the first, middle, and last usable cuts (blooms) of the strand or product shall be taken. 4.3.1.4 Remelted Heats For all heats, regardless of the number of remelted ingots, samples shall be taken from remelted material representing the top of one electrode and

45、 the bottom of one electrode of the heat. 4.3.2 Product Qualification Three or more samples shall be taken at random from each lot; a lot shall be all product of the same size and shape from each heat in the shipment. SAE AMS2315G Page 6 of 7 4.4 Reports The vendor of the product shall report the av

46、erage percentage of delta ferrite (See 8.2) for each lot or heat, as applicable, provided no single specimen value was above the material specification maximum. The data supporting this statement shall be kept on file and available for review for the same period as other data supporting the specific

47、ation requirements. 4.5 Resampling and Retesting 4.5.1 Material represented by specimens not meeting requirements shall not be shipped or used without review and approval by the cognizant engineering organization except as allowed in 4.5.2. 4.5.2 Product Other Than Slabs, Plates, Sheet, and Strip If

48、 any specimen used in the above tests fails to meet the specified requirements, disposition of the heat or lot may be based on the results of testing specimens from 3 additional samples for each original nonconforming specimen; additional samples shall be as follows: 4.5.2.1 Heats of Top-Poured Ingo

49、ts One of the additional samples shall be taken from the same position from product from each of the two available ingots most immediately adjacent in pouring sequence to that from which the original nonconforming sample was taken. The third sample shall be taken from product of the original nonconforming ingot af