1、DRAFT FOR DEVELOPMENTDD CEN/TR 10347:2006Guidance for forming of structural steels in processingICS 77.140.10g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3
2、g47g36g58DD CEN/TR 10347:2006This Draft for Development was published under the authority of the Standards Policy and Strategy Committeeon 29 September 2006 BSI 2006ISBN 0 580 49285 0National forewordThis Draft for Development was published by BSI. It is the UK implementation of CEN/TR 10347:2006. T
3、he UK participation in its preparation was entrusted to Technical Committee ISE/12, Structural steels.A list of organizations represented on ISE/12 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsib
4、le for its correct application.Amendments issued since publicationAmd. No. Date CommentsTECHNICAL REPORTRAPPORT TECHNIQUETECHNISCHER BERICHTCEN/TR 10347April 2006ICS 77.140.10English VersionGuidance for forming of structural steels in processingGuide pour le formage des aciers de construction lors d
5、eleur mise en oeuvreHinweise fr das Umformen von Bausthlen bei derVerarbeitungThis Technical Report was approved by CEN on 13 March 2006. It has been drawn up by the Technical Committee ECISS/TC 10.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Es
6、tonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPIS
7、CHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. CEN/TR 10347:2006: E2 Contents Page Foreword 3 1 Scope .4 2 Terms and definitions.4 3 General principles.
8、4 4 Hot forming5 5 Cold forming7 6 Flame-straightening8 Bibliography.11 CEN/TR 10347:20063 Foreword This Technical Report (CEN/TR 10347:2006) has been prepared by Technical Committee ECISS/TC 10 “Structural steels Grades and qualities“, the secretariat of which is held by NEN. In the ECISS/TC 10 mee
9、ting of 8 and 9 December 1998 it was decided with Resolution ECISS/TC 10 no 2/1998 to publish ECSC IC 2 as a CEN report. The part on welding in ECSC IC 2 has been revised by CEN/TC 121 and has resulted in EN 1011-2. The part on formability has been revised in this CEN Technical Report. CEN/TR 10347:
10、20064 1 Scope This CEN Technical Report provides guidance for forming during processing of structural steel products conforming to EN 10025 Parts 2 to 6 and EN 10149 Parts 2 and 3. This Technical Report covers hot and cold forming processes and local hot forming used in flame-straightening operation
11、s. This Technical Report does not cover the special measures necessary for the fabrication of structural components that are subjected predominantly to alternating stresses or that come into contact with aggressive media. 2 Terms and definitions For the purposes of this Technical Report, the followi
12、ng terms and definitions apply. 2.1 hot forming forming at temperatures in the austenite range, generally around 900 C depending on the chemical composition of the steel grade 2.2 cold forming forming up to the highest temperature permissible for stress relieving, generally in the range of 530 C to
13、580 C NOTE See the relevant part of EN 10025 (e.g. 7.3.1.1 of EN 10025-1:2004 and 7.4.1.1 of EN 10149-1:1995). 2.3 flame-straightening local quick heating of a component with a short holding time (generally less than one minute) at the flame-straightening temperature 2.4 flame-straightening temperat
14、ure highest temperature arising in the component during flame-straightening 3 General principles With rising minimum yield strength values for structural steels and with an increasing wall thickness of structural steel products, extra care needs to be taken during subsequent processing of steel prod
15、ucts. Furthermore, the technical delivery conditions of steel products complying with EN 10025 and EN 10149 will depend on the actual process route used by the steel product manufacturer. In general, suitable steel grades for the special forming situation should be selected. EN 10025 also defines sp
16、ecial steel grades for cold forming and additional options for ensuring forming properties which should be preferably used. In cases which are not covered by these order options the steel manufacturer should be consulted. All steel grades of EN 10149 are suitable for cold forming. In individual case
17、s outside of the specific guidance given here, especially when using structural steels for the first time, forming should be based on prior experience. This may be based on pre-production procedure trials undertaken by the fabricator or on documented trials undertaken by the steel product manufactur
18、er. If a manufacturer wants to ensure that the hot forming, cold forming or flame-straightening process intended to be applied will not detrimentally influence the mechanical properties of the structure, a process verification should be performed. CEN/TR 10347:20065 NOTE Temperatures referred to in
19、this Technical Report are measured at the steel product surface and not somewhere in the furnace. Allowance should be made for the fact that the temperatures in the product may not be uniform. 4 Hot forming 4.1 General 4.1.1 The following products can generally be subjected to hot forming: null non
20、alloy structural steels supplied as-rolled for normalizing by the purchaser (see 7.3.1.3 of EN 10025-2:2004) or supplied in the normalized delivery condition conforming to EN 10025-2; null normalized fine-grain structural steels conforming to EN 10025-3 and EN 10149-3; null structural steels with im
21、proved atmospheric corrosion resistance supplied as-rolled for normalizing by the purchaser (see 7.3.1.3 of EN 10025-5:2004) or supplied in the normalized delivery condition conforming to EN 10025-5. It is not envisaged that thermomechanical rolled steel grades conforming to EN 10025-2, EN 10025-4 a
22、nd EN 10149-2 or quenched and tempered steels conforming to EN 10025-6 should require further processing by hot forming. The strength properties of thermomechanical rolled steel grades, the material condition of which is not achievable or reproducible by a heat treatment alone, are impaired by hot f
23、orming during further processing. For quenched and tempered steels the necessary heat treatment after hot forming is very difficult to reproduce. 4.1.2 Where special hot forming operations are performed, e.g. hole flanging or inductive bending, the steel product manufacturer should be consulted. Pro
24、cess verification for induction bending should ensure that both the steel and the process are matched. 4.1.3 Where only local heating to hot forming temperature is involved, other than flame-straightening, attention should be paid to the fact that, apart from the region heated in regular fashion to
25、normalizing temperature, areas appear with temperatures between the lower limiting temperature for normalizing and the upper limiting temperature for stress relieving. In these areas, the material properties can be impaired, depending on the heating technique, temperature, and duration involved. The
26、 area heated into the two phase regime ferrite-austenite is experienced to be particularly critical for both strength and toughness. 4.2 Temperature during hot forming To carry out hot forming, the work piece should be heated above 900 C, but not above 1050 C, preferably not above 1020 C. After reac
27、hing the planned temperature for the work piece, holding at that temperature to ensure a uniform temperature in the work piece is only necessary if stipulated in the relevant steel product standard. NOTE 1 The temperature of 900 C relates to the lower temperatures for normalizing. NOTE 2 For quenche
28、d and tempered steels see 4.1.1. Heating rates should be as fast as possible and holding times should be as short as possible. For this reason, work pieces should not be heated in a pile. CEN/TR 10347:20066 During hot forming, the temperature should not drop below the lower limit of admissible tempe
29、ratures as given in Table 1. In particular, when the product thickness is small (less than 15 mm) the heat flow from the work piece to the forming devices should be taken into account during hot forming. After hot forming, the work piece should generally be cooled in air, in order to ensure a minimu
30、m of deformation due to internal stresses. The cooling rate should be kept as similar as possible to the one applied to the original product. In general, the cooling rate after hot forming depends on the shape and wall thickness of the component. In particular, the cooling rate of products with a sm
31、all thickness is significantly higher when the work piece is cooled in contact with the forming devices than in contact with air. For this reason, retarded cooling or tempering may be necessary in special cases for normalized steel grades with minimum yield strength values equal to or greater than 4
32、20 MPa and small wall thickness (less than 15 mm). Details should be obtained from the steel product manufacturer. The temperature should be monitored in all hot forming operations in order to ensure that, during the forming operation, the highest allowable temperature is not exceeded (see 4.3.2). T
33、his is of particular importance where the heat treatment of the work piece is not intended to be repeated after forming. 4.3 Heat treatment after hot forming 4.3.1 Heating to a temperature greater than about 50 K above the transformation temperature Ac3, at which austenitization is completed, in par
34、ticular if combined with a long holding time, leads to grain growth and thereby impairs the toughness properties and the yield strength. For this reason, after hot forming the finished component should be heat treated generally in accordance with the advice of the steel product manufacturer or the r
35、elevant steel product standard. It is essential that normalized steel grades are renormalized. This is of particular importance where fabrication processes require the normalizing of the component after hot forming. Under these circumstances, a normalized steel product could be ordered in the as-rol
36、led delivery condition. The steel product manufacturer should be consulted for advice. 4.3.2 With normalized steel grades, normalizing after hot forming may be omitted in the following cases: a) After single-step hot forming, normalizing of the finished component may be omitted if the process has be
37、en undertaken within the limits given in Table 1. CEN/TR 10347:20067 Table 1 Criteria for omitting renewed heat treatment after single-step hot forming Lowest temperature at the end of hot forming with the degree of hot formingaTest temperature for verification of Charpy impact energy Steel grade Ma
38、ximum temperature before hot forming 5 % 5 % C C C C S235-S355 980 - 20 S420-S460 940 S235-S355 940 460 MPa. In such cases, it is very advisable that the steel product manufacturer is consulted for advice. In addition to the elevated temperature effect on the microstructure, metallurgical precipitat
39、ion processes play an additional role with regard to water-quenched and tempered steel grades. For this reason the flame-straightening temperature should be kept strictly at least 20 K lower than the tempering temperature. 6.2.3.2 When the flame-straightening temperatures are higher than 700 C, it s
40、hould be assumed that at least partial austenitizing of the material occurs. Where microstructure constituents richer in carbon and other alloy elements transform into austenite diffusion of additional carbon takes place from the regions still ferritic into those already austenitic. During subsequen
41、t rapid cooling, the austenitic regions transform into martensite, which might also be enriched in carbon. Increased hardness and lower toughness can result from that process. When the cooling rate is comparatively slower, a mixed microstructure is produced, with the risk that the yield strength dec
42、reases locally and falls short of the specified minimum value. At the same time, local enrichment in carbon can lead to an impairment of toughness properties. The change in toughness is, however, less marked than in the case of rapid cooling from temperatures where austenite is present. The possible
43、 impairment of toughness properties by flame-straightening is greater with increased carbon content of the steels. Heating of the full cross-section of the component to temperatures above 700 C will result in an impairment of the strength and toughness properties. Flame-straightening temperatures ab
44、ove 950 C should be avoided even if the heating of the component is only superficial. CEN/TR 10347:200610 6.3 Maximum values of the flame-straightening temperature Recommended maximum values of the flame-straightening temperature as a function of the steel type and of the flame-straightening techniq
45、ue are given in Table 2. Table 2 Recommended maximum values of the flame-straightening temperatureRecommended maximum values of the flame-straightening temperature Short superficial heating Short full section heating Full section heating with longer holding time Delivery condition C C C normalized 9
46、00 700 650 thermomechanical rolled up to S460 900 700 650 thermomechanical rolled S500 to S700 900 600 550 quenched and tempered tempering temperature applied to the original product 20 K (generally below 550 C)CEN/TR 10347:200611 Bibliography EN 1993-1-10, Eurocode 3: Design of steel structures - P
47、art 1-10: Material toughness and through-thickness properties EN 10025-1, Hot rolled products of structural steels Part 1: General technical delivery conditions EN 10025-2, Hot rolled products of structural steels Part 2: Technical delivery conditions for non-alloy structural steels. EN 10025-3, Hot
48、 rolled products of structural steels Part 3: Technical delivery conditions for normalized/normalized rolled weldable fine grain structural steels. EN 10025-4, Hot rolled products of structural steels Part 4: Technical delivery conditions for thermomechanical rolled weldable fine grain structural st
49、eels. EN 10025-5, Hot rolled products of structural steels Part 5: Technical delivery conditions for structural steels with improved atmospheric corrosion resistance. EN 10025-6, Hot rolled products of structural steels Part 6: Technical delivery conditions for flat products of high yield strength structural steels in the quenched and tempered condition. EN 10149-1, Hot-rolled flat products made of high yield strength steels for cold forming Part 1: General delivery conditions EN 10149-2, Hot-rolled flat products made o
