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1、BRITISH STANDARD AEROSPACE SERIES CONFIRMED SEPTEMBER 1999 BS HC 403:1977 (Superseding Ministry of Defence Specification DTD 485A) Specification for High chromium alloy cast iron ring pots (centrifugally cast) (Suitable for piston rings up to 400 mm in diameter) UDC 629.7:62 242.3:669.15.26 196 Lice
2、nsed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS HC 403:1977 This British Standard, having been prepared under the direction of the Aerospace Standards Committee, was published under the authority of the Executiv
3、e Board on 31 December 1976 BSI 01-2000 The following BSI references relate to the work on this standard: Committee reference ACE/60 Draft for comment 73/38194 DC ISBN 0 580 09690 4 A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards
4、are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages 1 to 3 and a back cover. This standard has been updated (s
5、ee copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+0
6、0:00 2006, Uncontrolled Copy, (c) BSI BS HC 403:1977 BSI 01-2000i Contents Page 1Inspection and testing procedure1 2Chemical composition1 3Condition1 4Heat treatment1 5Selection and preparation of test samples1 6Mechanical properties1 7Microscopic examination2 Appendix A Method for determination of
7、modulus of elasticity3 Appendix B Method for determination of ring tensile strength3 Figure 1 Application of diametral force3 Figure 2 Application of tangential force3 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+00:00 2006, Uncontrolled Copy, (c
8、) BSI ii blank Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS HC 403:1977 BSI 01-20001 1 Inspection and testing procedure This British Standard shall be used in conjunction with sections 1 and 5 of the late
9、st issue of BS HC 100. 2 Chemical composition 2.1 The castings shall contain: 2.2 At the discretion of the Approved Metallurgist, minor deviations from the specified analysis range and impurity elements shall be permitted provided that they do not deleteriously affect the metallographic structure an
10、d mechanical properties. 3 Condition The castings shall be supplied annealed. 4 Heat treatment 4.1 Annealing. The annealing treatment shall consist of heating uniformly at a temperature between 950 C and 1 050 C, for a suitable length of time to achieve the required degree of carbide breakdown, and
11、cooling slowly. 4.2 Final heat treatment. The final heat treatment applicable to components machined from the castings shall consist of the following. a) Hardening. Heat uniformly at a temperature between 860 C and 890 C and quench in oil. b) Tempering. Heat uniformly at a temperature between 500 C
12、and 650 C, depending on the hardness required (see 6.2.2), and cool in air. 5 Selection and preparation of test samples 5.1 The inspector shall select test samples for the modulus of elasticity and ring tensile tests from at least one pot from each cast. 5.2 The test samples shall be cut from any po
13、sition not less than 20 mm from the non-flanged end of the pot. 5.3 The test pieces machined from the test samples (see A.1 and B.1) shall not be further mechanically or thermally worked before testing. 6 Mechanical properties NOTEInformation on SI units is given in BS 3763 “The International System
14、 of units (SI)” and BS 350 “Conversion factors and tables”. 6.1 Modulus of elasticity and ring tensile strength 6.1.1 Initial tests. The properties obtained from the test pieces, machined from the test samples selected and prepared in accordance with clause 5, shall comply with the following require
15、ments. 6.1.1.1 Modulus of elasticity. When determined as described in Appendix A, the modulus of elasticity shall be not less than 138 000 MPa. Either of the methods described in Appendix A may be used, but in cases of dispute results from the same method shall be compared, i.e. both tangential load
16、ing or both diametral loading. 6.1.1.2 Ring tensile strength. When determined as described in Appendix B, the ring tensile strength shall be not less than the following value. 6.1.2 Retests. If any test piece fails to comply with the requirements of 6.1.1.1 or 6.1.1.2, all the pots represented, shal
17、l be withdrawn or, if requested by the founder, the inspector shall adopt one of the following procedures. a) Select for test further samples from two pots from the same cast, one of which shall be taken from the pot from which the original test sample was taken, unless that pot has been withdrawn b
18、y the founder. The properties obtained from test pieces machined from both these further samples shall comply with the requirements of 6.1.1.1 or 6.1.1.2, as appropriate. b) Allow the cast to be reannealed in accordance with 4.1 and retested in accordance with 6.1.1, 6.2 and clause 7. Element % min.
19、max. Total carbon2.83.1 Silicon1.92.5 Manganese0.71.0 Phosphorus0.30.45 Sulphur0.08 Chromium0.751.15 Chromium + molybdenum2.1 aCopper 0.2 Molybdenum0.81.0 aNickel 0.3 aTitanium 0.12 a This element is not to be added deliberately. Nominal outside diameter of pot Ring tensile strength mmMPa Up to and
20、including 150 Over 150 625 575 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS HC 403:1977 2 BSI 01-2000 6.2 Hardness 6.2.1 The hardness of castings heat treated in accordance with 4.1 shall be: 6.2.2 The ha
21、rdness of material finally heat treated in accordance with 4.2 shall be: 7 Microscopic examination 7.1 The inspector shall select a sample from each pot for microscopic examination. 7.2 The sample shall be selected from a discard ring cut from any position not less than 20 mm from the non-flanged en
22、d of the pot and the area prepared for examination shall be representative of the area which will be left after machining. 7.3 The prepared area shall be examined microscopically and, except as provided in 7.4, shall comply with the following requirements. 7.3.1 The unetched surface shall reveal an
23、aggregate of short graphite flakes and temper carbon. 7.3.2 After etching, the structure shall consist of non-acicular carbide in a matrix of lamellar pearlite. 7.4 Alternatively to 7.3, standards of acceptance shall be agreed between the founder and the purchaser, and photomicrographs depicting the
24、 agreed standards shall be prepared. min.max. HB or HV or HRC 269 285 28 302 320 33 Tempering temperature 500 C650 C min.max.min.max. HB or HV or HRC 444 475 47 534 610 53 285 300 31 331 350 36 Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+00:00 2
25、006, Uncontrolled Copy, (c) BSI BS HC 403:1977 BSI 01-20003 Appendix A Method for determination of modulus of elasticity A.1 Test piece The test piece required is a ring machined from the test sample to a radial thickness of not less thanand with a piece cut out so as to leave a free gap of not less
26、 than 2.75 times or more than 3 times the radial thickness. A.2 Procedure Use the following procedure. a) Measure the width of the free gap. b) Apply to the ring, either diametrally, as shown in Figure 1, or tangentially, as shown in Figure 2, a force sufficient to close the gap to less than 0.25 ti
27、mes the radial thickness. c) Allow the ring to open and then apply the force again as in b). d) Measure the circumference of the ring in the closed position, by means of a calibrated tape or other equivalent method, and calculate the mean external diameter. e) Measure the width of the gap in the clo
28、sed position and calculate the change in width of the gap. A.3 Determination of result Determine the modulus of elasticity (E) from the appropriate formula as follows. a) Diametral loading b) Tangential loading where Appendix B Method for determination of ring tensile strength B.1 Test piece The tes
29、t piece required is a ring machined from the test sample to an approximately square section, or to a section approximating to that of a finished ring, and slit radially. B.2 Procedure Use the following procedure. a) Mount the test piece in a suitable testing machine. b) At radially opposite points o
30、n the diameter perpendicular to the diameter through the slit, gradually apply a tensile force until fracture occurs. c) Note the force at fracture. B.3 Determination of result Determine the ring tensile strength (S) from the following formula. Figure 1 Application of diametral force Figure 2 Applic
31、ation of tangential force diameter 26 - - dis the mean outside diameter of the closed ring (mm), tis the radial thickness of the ring (mm), Q is the diametral force (N), T is the tangential force (N), bis the axial breadth of ring (mm), xis the change in width of gap (mm), where D is the nominal out
32、side diameter of the unsplit ring (mm), P is the tensile force at fracture (N), bis the axial breadth at back of ring (mm), tis the radial thickness at back of ring (mm), Licensed Copy: London South Bank University, London South Bank University, Sat Dec 09 03:18:40 GMT+00:00 2006, Uncontrolled Copy,
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