1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA
2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any
3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 978-0-626-21496-8 SANS 26:2008Edition 2.1Any reference to SABS 26 is deemedto be a reference to this standard(Government Notice No. 1373 of 8 Novemb
4、er 2002)SOUTH AFRICAN NATIONAL STANDARD Zinc alloy die-castings Published by Standards South Africa 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: 012 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa SANS 26:2008 Edition 2.1 Table of cha
5、nges Change No. Date Scope Amdt 1 2008 Amended to change the designation of SABS standards to SANS standards, to update the definition of “acceptable“, to delete reference to the SABS and the standardization mark scheme, and to update a referenced standard. Acknowledgement Standards South Africa wis
6、hes to acknowledge the valuable assistance derived from publications of the following organizations: American Society for Testing and Materials British Standards Institution Imperial Smelting Corporation International Organization for Standardization Mazak Ltd Zinc Alloy Die-Casters Association Fore
7、word This South African standard was approved by National Committee StanSA TC 5120.78, Engineering materials Non-ferrous metals, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. This document was published in July 2008. This document super
8、sedes SABS 26:1977 (edition 2). A vertical line in the margin shows where the text has been technically modified by amendment No. 1. A reference is made in 6.3, NOTE (a), to “relevant body“. In South Africa this means Standards South Africa in terms of the Standards Act, 1993 (Act No. 29 of 1993). S
9、ANS 26:2008 Edition 2.1 1 Contents Page Acknowledgement Foreword 1 Scope 3 2 Definitions . 3 3 Requirements 4 4 Packing and marking . 6 5 Sampling and compliance with the specification 6 6 Inspection and methods of test 6 6.1 Inspection . 6 6.2 Preparation of test samples 7 6.3 Analysis of the casti
10、ngs metal . 7 Appendix A Applicable standards . 8 Appendix B Notes to purchasers . 8 Appendix C Determination of minimum mass . 9 Appendix D Characteristics and properties of the zinc-base alloys for die-castings 9 SANS 26:2008 Edition 2.1 2 This page is intentionally left blank SANS 26:2008 Edition
11、 2.1 3 Zinc alloy die-castings 1 Scope 1.1 This specification covers die-castings made from zinc alloy ingots that comply with the requirements of SANS 25. NOTE a) The titles of standards referred to by number in the specification are given in appendix A. b) Requirements that must be specified by th
12、e purchaser and those that must be agreed upon are listed in appendix B. c) Compliance with the requirements of 3.1, the provision of samples and the testing to determine the permissible extent of porosity and the minimum mass (see 3.3) and (where relevant) assessment of compliance with the requirem
13、ents for stabilization (see 3.5) require special agreement between the manufacturer and the purchaser. A recommended method of determining the minimum mass is given in appendix C. d) Characteristics and properties of the zinc-base alloys for die-castings are given in appendix D. 2 Definitions 2.1 Fo
14、r the purposes of this specification the following definitions shall apply: acceptable acceptable to the authority administering this standard, or to the parties concluding the purchase contract, as relevant Amdt 1 cast (batch) a) die-castings produced from one furnace or crucible melt; or b) die-ca
15、stings produced from a number of crucible or furnace melts that have been combined and mixed before casting; or c) die-castings consecutively produced from a continuous melting furnace or a continuous casting operation during a maximum period of 8 h on the same day, during which all metal added to t
16、he furnace, in either the liquid or the solid form, is such that the composition of the castings remains uniform defective a die-casting that fails in one or more respects to comply with the relevant requirements of the specification SANS 26:2008 Edition 2.1 4 lot all die-castings of the same nomina
17、l composition and bearing the same cast identification made by one manufacturer, submitted at any one time for inspection and testing 3 Requirements 3.1 General All die-castings shall be manufactured from zinc alloy ingots complying with the relevant requirements of SANS 25 (see 3.6). Any scrap used
18、 shall be derived only from such ingot metal and shall consist of clean reject castings (free from inserts and from any plating that may be detrimental), together with clean gates, sprues, and runners arising from the manufacturers own production. The ratio of virgin alloy ingot to process arisings
19、in the melt shall be as agreed upon between the purchaser and the manufacturer. 3.2 Chemical composition The composition of die-casting, determined in accordance with 6.3, shall comply with the requirements given in table 1 appropriate to SA code number specified by the purchaser. 3.3 Porosity and m
20、inimum mass 3.3.1 Porosity Die-castings shall be clean and shall not exhibit harmful porosity. The permissible extent of any porosity for each design of die-casting shall be as agreed upon between the purchaser and the manufacturer. 3.3.2 Minimum mass The minimum mass of the die-castings, determined
21、 by any acceptable method, shall be at least the value agreed upon between the manufacturer and the purchaser. (A recommended method for determining the minimum mass is given in appendix C.) 3.4 Dimensions The dimensions of the die-castings shall (subject to tolerances agreed upon between the manufa
22、cturer and the purchaser) be as shown on the drawing. 3.5 Dimensional stability Die-castings shall normally be supplied in the “as cast“ condition but, when so required by the purchaser, they shall have been dimensionally stabilized by being maintained for 6 h at a temperature of 100 5 C in air, and
23、 then allowed to cool in air. NOTE For the purpose of ascertaining compliance with the requirement for dimensional stabilization (when applicable), the purchaser should arrange with the manufacturer for a representative to be present when stabilization is carried out. Amdt 1 3.6 Certification When s
24、o required by the purchaser, each lot (consignment) shall be accompanied by a certificate stating that the die-castings were made from ingots that comply with the relevant requirements of SANS 25 and that the die-castings comply with the appropriate requirements of the specification and containing c
25、onfirmatory analytical results. Table 1 Chemical composition 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Alloying constituents Impurities % % SA code No. Zn Al Mg Cu Fe Cu Pb Cd Sn Ni Tl ln ZBD1 min. 3,8 0,03 max. 4,3 0,06 0,10 0,10 0,005 0,005 0,002 0,006 0,001 0,000 5ZBD2 min. 3,8 0,03 0,75 max. Remainder 4,
26、3 0,06 1,25 0,10 0,005 0,005 0,002 0,006 0,001 0,000 55 SANS 26:2008 Edition 2.1SANS 26:2008 Edition 2.1 6 4 Packing and marking 4.1 Packing Die-castings shall be packed in containers that are strong enough to prevent damage to the die-castings during normal transportation. 4.2 Marking Die-castings
27、shall be acceptably marked with the following information by a method agreed upon between the manufacturer and the purchaser: a) the manufacturers name or trade name or trade mark; b) the SA code number (see table 1); c) the cast (batch) identification or a cypher signifying this information; d) whe
28、re practicable and where applicable, a number identifying each die impression; e) if the die-castings have been dimensionally stabilized, the letter “S“ after the SA code number. 5 Sampling and compliance with the specification1)5.1 Sampling The following sampling procedure shall be applied in deter
29、mining whether a lot complies with the requirements of the specification. The samples so taken shall be deemed to represent the lot for the respective properties. 5.1.1 Sample for inspection and determination of minimum mass From the lot take at random 5 % of the die-castings in the lot. 5.1.2 Sampl
30、e for (Physico-) chemical and spectrographic analysis From the sample taken in accordance with 5.1.1 take at random one casting. 5.2 Compliance with the specification The lot shall be deemed to comply with the specification if after inspection and testing of the samples taken in accordance with 5.1
31、no defective is found. 6 Inspection and methods of test 6.1 Inspection Inspect the sample taken in accordance with 5.1.1 for compliance with the requirements of 3.4 and section 4. 1) This section applies to the sampling for inspection and testing before acceptance or rejection of single lots (consig
32、nments) in cases where no information about the implementation of quality control or testing during manufacture is available to help in assessing the quality of the lot. It is also used as the procedure for adjudicating in cases of dispute. SANS 26:2008 Edition 2.1 7 6.2 Preparation of test samples
33、6.2.1 For (Physico-) chemical analysis Degrease the casting in the sample taken in accordance with 5.1.2 and so machine it as to provide sufficient drillings or millings for the required analysis procedures. Mix the machinings thoroughly and treat them with a powerful magnet to ensure that any iron
34、contamination is removed. 6.2.2 For spectrographic analysis Cut as many complete sections from the sample taken in accordance with 5.1.2 as to provide enough metal for the preparation of the test sample. Immerse the pieces for a few moments in hydrochloric acid (5 % (m/m), rinse in distilled or demi
35、neralized water, and dry. Then melt the pieces together, without flux, in a clean carborundum or silica crucible and at no time allow the temperature of the melt to rise above 425 C. Skim and stir the melt with a clean dry wooden stick or silica rod then, using a casting temperature of not more than
36、 425 C and not less than 410 C, cast the melt vertically into a suitable clean cast iron or mild steel mould that has been preheated to 100 C. 6.3 Analysis of the castings metal Using any recognized and acceptable physico-chemical method2)or other method determine, in a representative portion of the
37、 test sample (6.2), the content of each element for which limits are specified in columns 4-14 of table 1. Amdt 1 NOTE a) In cases of dispute the methods adopted by the relevant body (see foreword). Amdt 1 b) To verify compliance with the limits given in the table, use the following rules to round o
38、ff the test results to the minimum number of figures necessary to assess compliance: 1) When the figure immediately after the last figure to be retained is lower than 5, the last figure to be retained remains unchanged. 2) When the figure immediately after the last figure to be retained is greater t
39、han 5, or is equal to 5 and is followed by at least one figure other than zero, the last figure to be retained is increased by one. 3) When the figure immediately after the last figure to be retained is equal to 5 and is followed by zeros only, the last figure to be retained remains unchanged if eve
40、n and is increased by one if odd. 2) Such as ASTM E27. Amdt 1 SANS 26:2008 Edition 2.1 8 Appendix A3)Applicable standards Reference is made to the latest issues of the following standards: ASTM Method E27, Spectrochemical analysis of zinc-base alloys and high-grade zinc by the solution residue D-C a
41、rc technique. Amdt 1 SANS 25, Zinc alloy ingots for die-castings. Appendix B Notes to purchasers B.1 The following requirements must be specified in tender invitations and in the order or contract: a) The SA code number (see 3.2 and table 1) b) If required, that the die-castings shall have been subj
42、ected to dimensional stabilization (see 3.5) c) If required, that a certificate of compliance is to accompany each lot (see 3.6) B.2 The following requirements must be agreed upon between the purchaser and the manufacturer: a) The ratio of virgin alloy ingot to process arisings in the melt (see 3.1)
43、 b) The permissible extent of any porosity in the die-castings and the minimum mass (see 3.3) c) The tolerances on the dimensions of the die-castings (see 3.4) d) The method of marking of the die-castings (see 4.2) 3) The information in the appendices is additional to that in the specification and h
44、as been included purely for information and guidance. SANS 26:2008 Edition 2.1 9 Appendix C Determination of minimum mass NOTE a) The sampling and testing procedures described below should be carried out in the presence of representatives of the manufacturer and the purchaser. b) When so required by
45、 the purchaser, the minimum mass may be re-determined at any time during the course of production of the die-castings. C.1 a) From each die impression (suitably marked for purposes of identification) used in the production run of the die-castings take, at random, 10 die-castings. b) Determine the ma
46、ss of each die-casting in the sample. Fracture the die-castings at places selected by prior agreement between the manufacturer and the purchaser. Reject those die-castings that show porosity that, by agreement, is deemed to be harmful and replace them with other die-castings taken at random from the
47、 product of the same die impressions. C.2 Repeat the procedure described in C.1(b) until 10 die-castings from each die impression have been found to be satisfactory and take the mass of the lightest as the minimum mass. Appendix D Characteristics and properties of the zinc-base alloys for die-castin
48、gs The establishment of dependable zinc-base die-casting alloys was the result of a considerable amount of research, and the two alloys for zinc alloy ingots and zinc alloy die-castings given in the specifications have found acceptance throughout most of the industrial world. It should be noted that
49、 a larger tolerance in composition is permitted for the die-castings, to allow for the remelting procedure. Although it was discovered that the chosen compositions gave the optimum balance of properties, the major factor which emerged from the research work was that severe restrictions on certain impurities were necessary to prevent intercrystalline corrosion with subsequent breakdown of dimensional stability and loss of strength of the alloys. The significance of this fact is reflected in the level of impurity limits imposed for ingots
