BS 5046-1974 Method for the estimation of equivalent diameters in the heat treatment of steel《钢热处理的等效直径评估方法》.pdf

1、 This British Standard, having been approved by the Iron and Steel Industry Standards Committee, was published under the authority of the Executive Board on 29 March, 1974. 0 British Standards Institution, 1974 ISBN: O 580 07998 8 Copyright Users of British Standards are reminded that copyright subs

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7、 will be welcomed, and should be made to Subscriptions Department. Both departments are located at: 101 Pentonville Road, London N1 9ND (Telephone 01-837 8801 ; Telex 23218). The following BSI references relate to the work on this standard: Committee reference ISE/-/6 Draft for comment 72/42290DC Co

8、-operating organizations The iron and Steel Industry Standards Committee, under whose supervision this standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: British Czst Iron Research Association British Construction

9、al Steelwork Association British Electrical and Allied Manufacturers Association British Ironfounders Association British hfechanical Engineering Confederation British Sfeel Industry Concrete Society Council of Iron Producers Council of Ironfoundry Associations Department of Employment Department of

10、 Trade and Industry (hlarine Division) Engineering Equipment Users Association Federation of Civil Engineering Contractors Greater London Council Institute of British Foundrymen Institute of Iron and Steel Wire Manufacturers Insfitute of Marine Engineers Instifution of Mechanical Engineers (Automobi

11、le Divismn) Institution of Production Engineers Institution of Structural Engineers Lloyds Register of Shipping Ministry of Defence Ministry of Defence, Army Department Ministry of Defence, Procurement Executive National Association of Drop Forgers and Stampers Oil Companies Materials Association Pr

12、ocess Planf Association Royal Institute of British Architects Shipbuilders and Repairers National Association Society of Motor Manufacturers and Traders Ltd. Steel Castings Research and Trade Association Tin Research Institute f t- o i 7403-2k-B Method for The estimation of equivalent diameters in t

13、he heat treatment of steel Amendments issued since publication Amd. No. Date of issue Text affected British Standards Institution 2 Park Street London WIA 2BS Telephone O1 -629 9000 Telex 266933 BSI BSr504b 74 S Lb24669 00775b0 7 BS 5046 : 1974 o Contents Page Co-operating organizations Inside front

14、 cover Foreword 2 Method 1. Scope 3 2. Terminology 3 3. Tables of equivalent diameters 4 3.1 General 4 3.2 Cylinders and discs 4 3.3 Rectangular sections, including plates 11 3.4 Tubes and rings 15 3.5 Shapes consisting of combinations of 2 or 3 cylinders with common axis 18 Append ices A. Informati

15、on on the basis of calculation of the tables 26 B. Two- and three-cylinder problems 31 C. Miscellaneous shapes 34 Tables 1. Equivalent diameters for cylinders and discs, 2. Equivalent diameters for cylinders and discs, 3. Equivalent diameters for cylinders and discs, 4. Equivalent diameters for rect

16、angular sections, 5. Equivalent diameters for rectangular sections, 6. Equivalent diameters for rectangular sections, air cooled 6 oil quenched 8 water quenched 10 air cooled 12 oil quenched 13 water quenched 14 Page wall thickness, y 16 to wall thickness, y 16 applied to wall thickness, y 16 axial

17、thickness, z 17 to axial thickness, z 17 applied to axial thickness, z 17 27 7. Tubes, air cooled: f factors to be applied to 8. Tubes, oil quenched: f factors to be applied 9. Tubes, water quenched: f factors to be 10. Rings, air cooled: f factors to be applied to 11; Rings, oil quenched: f factors

18、 to be applied 12. Rings, water quenched: f factors to be 13. Values for f for varying heat-transfer factors Figures 1. Two-cylinder objects: stages in calculation 2a. Two-cylinder objects: factor f when Eo Z d 2b. Two-cylinder objects: factor f whenE, d, calculate - and - , and from Fig. 2a estimat

19、e the value of a factor f. Then the product fE0 gives the equivalent diameter of the object in Fig. Ib, i.e. E,. b. If Eo d (200). Hence from Fig. 2a, f= 1.140 HenceE, = 1.140XEo= 1.140X220=251mm = 360mm 100 X 400 200 I = 1604- E = equivalent diameter of cylinder 400 mm dia. X 360 mm long = 344mm (2

20、5 1 - 220)(344 - 220) 400 - 220 31 X 124 180 E = 220+ = 220 + = 241 mm or, say, 240mm. 18 BS 5046 : 1974 d L D D D = 600, L = 200,d = 400, I = 200, -= 0.67, -=-0.33 By Table 2, the equivalent diameter of L.H. cylinder = 290 mm =Eo Here Eo d (200). Hence from Fig. 2a, f = 1.130 Hence E, = 1.130 X 230

21、 = 260mm = 1660mm 500 X 600 200 I = 160+ E = equivalent diameter of cylinder 600 mm dia. X 1660mm long = 600mm (260 - 230)(600 - 230) 600 - 230 30X 370 370 Hence Ei = 230 + = 230 + = 260mm. The length of a cylinder of diameter 600 mm (the diameter of the dominant cylinder) and equivalent diameter 26

22、0 mm is 180 mm. Combine this with the remaining cylinder. In the notation of 3.5.1 : d L D D D=600,L=180,d=300,1=100,-=0.5,-=0.30 Eo (260) d (300). Hence from Fig. 2b, f = 1.095 Hence E, = 1.095 X 300 = 328 mm = 380mm 100 X 600 300 I = 180+ E = equivalent diameter of tylinder 600 mm diaX 380 mm long

23、 = 446 mm (328 - 26)(446 - 260) 600 - 260 68X 186 340 Hence E = 260 + = 260 + = 297 mm, or say 300 mm. 20 :iSO)- (255)- BS 5046 : 1974 100 Oil quenched The R.H. cylinder dominates. Combine with the adjacent cylinder. In the notation of 3.5.1 : D = 600, L = 100,d = 400, I= 200, -= 0.67, - = 0.17 Eo (

24、150) d (400). Hence from Fig. 2b, f = 1.002 and E, =401 mm d L D D = 400 200 X 600 400 I = 100 + E = equivalent diameter of cylinder 600 mm dia. X 400 mm long = 460 mm (401 - 150)(460 - 150) 600 - 50 251 X 310 450 Hence Ei = 150 + = 150+ = 323 mm. The length of a cylinder of diameter 400 mm (the dia

25、meter of the dominant cylinder) and equivalent diameter Combine this with the final, L.H., cylinder. In the notation of 3.5.1 : D = 800, L = 50,1= 307, d = 400, -= 0.5, -= 0.063 Eo (78) d (400). Hence from Fig. 2b, f = 1 .O0 and E, = 400 mm 323 mm is 307 mm. d L D D = 664mm 307 X 800 400 I = 50 + E

26、= equivalent diameter of cylinder 800 mm dia. X 664 mm long = 666 mm (400 - 78)(666 - 78) . 800-78 322 X 588 722 E =78+ = 78 + = 340mm. 21 BSI BS*504b 74 lb24bb9 0077579 b W BS 5046 : 1974 a. ID L d C. Fig. I. Two-cylinder objects: stages in calculation 22 9 - O (9 O I. O 9 O 2 t O m d O - o O 3 F-

27、23 BS - BSI BS*504b 74 I I1624669 0077583 4 I 5046 : 1974 *c 24 O .u! O blQ BS 5046 : 1974 a. b. Fig. 3. Threecylinder objects 25 BSI BS*504b 74 M Lb24bb 0077583 8 BS 5046 : 1974 Appendix A Information on the basis of calculation of the tables A.l Equivalent cooling rate. If an irregular object is a

28、llowed to cool in some way, e.g. in air, it is theoretically impossible to fiid an equivalent size of bar which, when cooled in the same way, will give a cooling curve at the axis which will be exactly the same as“the cooling curve at the slowest point in the object. In practice, the match between t

29、he two cooling curves can be remarkably good, but nevertheless the above means that for purposes of calculation some special criterion of equivalent rate must be chosen. temperature, or equality of times to reach some chosen temperature. For the purposes of this standard, the criterion used for many

30、 years in Appendix E of the now obsolete 1955 edition of BS 970 has been retained, i.e. equality of times for the temperature to fall to a chosen fraction of the overall fall in temperature, this fraction being taken as 0.35; in other words, equality of times such that: A number of criteria have bee

31、n suggested, the most usual being equality of actual cooling rate at some chosen Temperature at slowest cooling point in the object and bar - temperature of cooling medium initial temperature of the object and bar - temperature of cooling medium For most direct-hardening steels, 0.35 corresponds to

32、a temperature round the start of the martensite change = 0.35 (Ms), but even for austenitic steels this fraction produces results adequate for most purposes. 14.2 Calculations. The calculations for short cylinders and rectangular sections for steels were based on the methods described in First Repor

33、t of the Alloy Steel Research Committee, Iron and Steel Institute Special Report No. 14 1936 p. 149, but were checked by direct calculation using fiiite-difference methods on an ICL 1905F computer. The calculations for rings and tubes were all performed on this computer. Initially, an assumption was

34、 made that all the tubes had a constant wall-thickness, and all the rings a constant axial thickness, of 1 O0 mm, but spot checks with other thicknesses suggest that the variation in the factors with size is of no significance for practical purposes. Heat-transfer factors, h (as defined in the above

35、 Report) based on practical experience were taken to be: For air cooling 0.003 mm- For oil quenching 0.08 mm- For water quenching 0.2 mm- Initially, the results for short cylinders and for long slabs were calculated as a multiplying factor f on either the diameter or the shorter dimension of the sec

36、tion of the slab, and were then converted to the tabular form shown in Tables 1 to 6. However, to facilitate interpolation, or where different h-values may be chosen, Figs. 4, 5 and 6 are provided. Fig. 4 refers to cylinders, and shows the variation off with the product hD where D is the diameter of

37、 the cylinder. Fig. 5 refers to rectangular sections (infinite length), and shows the variation off with the product hT where T is the thickness or shorter dimension of the section. Fig. 6 refers to discs, and shows the variation off with the product hTwhere Tis the thickness of the disc. Table 13 c

38、ompares the values off for values of h between zero (an infmitely slow quench) and infinity (the surface-temperature of the object instantaneously falling to the temperature of the cooling medium), and for a selection of typical objects. It will be seen that there is often little difference between

39、f for oil quench and for water quench (or indeed for h = CO) the main differences appearing at the smaller sizes of object. It is for this reason that the tables for water-quench are quoted only for small-sized objects, together with the instruction that for other sizes the oil- quench values should

40、 be taken. As stated in 2.2, it is emphasized that the equivalent diameter for different cooling media in no way reflects the actual cooling rates in those media. To provide further information on the effect of different quenching conditions (Le. vasring h) on the f-factors, 26 Table 13. Values for

41、f for varying heat-transfer factors Rectangular sections T/B = O (plate, B = m) T/B = 0.5 T/B = 1.0 Discs* TfD = 0.5 T/D = 1.0 Cylinderst D/L = 0.5 Coohg Air Oil- Water- condition cool quench quench h (mm-) O 0.003 0.080 0.200 00 T 10mm 100mm 1000 mm 1omm 100 mm 1 O00 mm 10mm 100 mm 1000 mm T 10mm 1

42、oomm 1ooomm 1omm 1 O0 mm 1ooomm D 10mm 1oomm 1000 mm 2.00 1.99 1.76 1.64 1.41 2.00 1.88 2.00 1.59 1.33 1.34 1.33 1.37 1.33 1.42 SO 1.45 1.41 .42 1.41 1.41 .40 1.42 1.36 .40 1.38 1.36 .36 1.36 1.36 1 .o0 1 .o0 1 .o4 1.07 1 .O9 1 .o0 1.01 1 .O8 1.08 1 .O9 1 .o0 1 .O8 1.09 1 .O9 1 .O9 1 .o0 1.01 1.15 1

43、,24 1.29 1 .o0 1 .O7 1.28 1.28 1.29 1 .o0 1.27 1.29 1.29 1.29 0.67 0.67 0.74 0.79 0.90 0.67 0.69 0.87 0.88 0.90 0.67 0.83 0.89 0.89 0.90 0.80 0.8 1 0.9 1 0.94 0.99 0.80 0.85 0.99 0.99 0.99 0.80 0.97 0.99 0.99 0.99 * T/D = O refers to plates and hence has the same factors as-for T/B = O (rectangular sections). D/L = 1.0 is given under Discs (T/D = 1.0); for D/L = O which is an infinitely long cylinder, f= 1.00 in ail cases. 27 BS 5046 : 1974 +q+ .! , : :ti : : .I I, + L Y- 0 r O CI o m Y- 6-l .- u. a .41fEl,.l.+T.l i, t -t. . i .i. I._ 29