MECHANICAL PROPERTIES OF CARBON STEEL AND STAINLESS STEEL

Transcription

1 Annex C MECHANICAL PROPERTIES OF CARBON STEEL AND STAINLESS STEEL C.1. MECHANICAL PROPERTIES OF CARBON STEEL C.1.1. Mehanial properties o arbon steel at room temperatre (0 ºC) Beore presenting the mehanial properties o arbon steel at elevated temperatre the properties at room temperatre will be given. The elasti onstants sed at room temperatre or the design o steel strtres are: - modls o elastiity E N/mm E - shear modls G N/mm (1 ) Poisson s ratio nit mass 7850 kg/m 3 The yield strength y and the ltimate tensile strength or hot rolled strtral steel and strtral hollow setions at room temperatre are given in the prodt standards EN 1005 EN 1010 and EN 1019 respetively. Simpliiations are given in Tables C.1 and C. whih are taken rom EN a Fire Design o Steel Strtres Jean-Mar Franssen and Palo Vila Real 01 ECCS Eropean Convention or Constrtional Steelwork. Pblished 01 by ECCS Eropean Convention or Constrtional Steelwork

2 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Table C.1: Nominal vales o yield strength Standard and steel grade or hot rolled strtral steel y and ltimate tensile strength Nominal thikness o the element t [mm] t 40mm 40mm < t 80mm y [N/mm ] [N/mm ] y [N/mm ] [N/mm ] 360 EN S S S S EN S75 N/NL S355 N/NL S40 N/NL S460 N/NL EN S75 M/ML S355 M/ML S40 M/ML S460 M/ML EN S 35 W S355 W EN S460 Q/QL/QL

3 C.1. MECHANICAL PROPERTIES OF CARBON STEEL Table C.: Nominal vales o yield strength or strtral hollow setions y and ltimate tensile strength Standard and steel grade Nominal thikness o the element t [mm] t 40mm 40mm < t 80mm y [N/mm ] [N/mm ] y [N/mm ] [N/mm ] EN S35 H S75 H S355 H S75 NH/NLH S355 NH/NLH S40 NH/NLH S460 NH/NLH EN S35 H S75 H S355 H S75 NH/NLH S355 NH/NLH S460 NH/NLH S75 MH/MLH S355 MH/MLH S40 MH/MLH S460 MH/MLH C.1.. Stress-strain relationship or arbon steel at elevated temperatres (withot strain-hardening) Aording to Part 1. o Eroode 3 the strength and stiness properties o steel at elevated temperatres shall be obtained rom the onstittive law desribed in Table C.3 and depited in Fig. C.1. This igre shows that the stress-strain relationship or arbon steel at elevated

4 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL temperatres split into or zones: a linear branh ntil the proportional limit is reahed; an ellipti transition whih ends at the eetive yield p strength y ; a yield platea; and inally a linear desending branh whih ors at large strains and an be sed in advaned allation models. In Table C.3 and Fig. C.1 the meaning o the symbols is: y p E a p y t eetive yield strength; proportional limit; slope o the linear elasti range; strain at the proportional limit; yield strain; limiting strain or yield strength; ltimate strain. Table C.3: Steel onstittive law at elevated temperatres Strain range Stress Tangent modls 36 p E a E a 0. 5 p < < p y b aa y b y 0. 5 y y t y 0 t < < y 1 t t a a - = Parameters p = p / E a y = 0.0 t = 0.15 = 0.0 Fntions a = y - p y - p + / E a b = - + = E a y p y - p y - p Ea - - y p

5 C.1. MECHANICAL PROPERTIES OF CARBON STEEL Stess y p E a = tan p y t = % = 15% = 0% Strain Fig. C.1: Stress-strain relationship or arbon steel at elevated temperatres The stress-strain relationship or arbon steel at elevated temperatres presented in Table C.1 is qantiied in Tables C.4 to C.7 or the steel grades S35 S75 S355 and S460 respetively. Graphial representation o the data given in Tables C.4 to C.7 is given in Figs C. to C.5 respetively. 363

6 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Table C.4: Stress-strain relationship or S35 arbon steel at elevated temperatres 364 Eetive yield strength y Strain Steel temperatre a [ºC]

7 C.1. MECHANICAL PROPERTIES OF CARBON STEEL Table C.5: Stress-strain relationship or S75 arbon steel at elevated temperatres Eetive yield strength y Strain Steel temperatre a [ºC]

8 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Table C.6: Stress-strain relationship or S355 arbon steel at elevated temperatres 366 Eetive yield strength y Strain Steel temperatre a [ºC]

9 C.1. MECHANICAL PROPERTIES OF CARBON STEEL Table C.7: Stress-strain relationship or S460 arbon steel at elevated temperatres Eetive yield strength y Strain Steel temperatre a [ºC]

10 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Stress º C º C 300º C 400º C 500º C º C º C 800º C Strain Fig. C.: Stress-strain relationship or S35 arbon steel at elevated temperatres St ress º C 50 00º C º C 400º C 500º C 600º C º C 800º C Strain Fig. C.3: Stress-strain relationship or S75 arbon steel at elevated temperatres

11 C.1. MECHANICAL PROPERTIES OF CARBON STEEL St ress º C 00º C 300º C 400º C 500º C º C º C 800º C Strain Fig. C.4: Stress-strain relationship or S355 arbon steel at elevated temperatres St ress º C º C 300º C º C 500º C º C º C 800º C Strain Fig. C.5: Stress-strain relationship or S460 arbon steel at elevated temperatres

12 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL C.1.3. Stress-strain relationship or arbon steel at elevated temperatres (with strain-hardening) For temperatres below 400 ºC the stress-strain relationship speiied in C. may be extended by adding the strain-hardening option given below providing loal or overall bkling does not lead to prematre ollapse. y y a 50 (C.1 a) a (C.1 b) a (C.1 ) (C.1 d) where: is the ltimate strength at elevated temperatre allowing or strain-hardening. This alternative stress-strain relationship or steel allowing or strain hardening is illstrated in Figre C.6. a 370 The ltimate strength at elevated temperatre allowing or strain hardening shold be determined as ollows: a 300º C 1. 5 y (C. a) 300 º C a 400º C y a (C. b) 400º C a y (C. )

13 C.1. MECHANICAL PROPERTIES OF CARBON STEEL Stress a a y p E a = tan a p y s t Strain Fig. C.6: Alternative stress-strain relationship or steel allowing or strain-hardening The variation o the alternative stress-strain relationship with temperatre is illstrated in igre C.7. a y º C 350º C 400º C º C Strain Fig. C.7: Alternative stress-strain relationship or steel allowing or strain-hardening or dierent temperatres

14 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL C.1.4. Mehanial properties to be sed with lass 4 ross setions and simple allation models Aording to the Eroode 3 advaned allation models may be sed or the design o Class 4 setions when all stability eets are taken into aont. This means that i the nmerial allation is arried ot sing the inite element method shell elements shold be sed to aptre loal bkling. The mehanial properties to be sed with advaned allation models are the ones deined in the previos setions o this annex. 37 With simple allation models the resistane o members with a Class 4 ross setion shold be veriied with the eqations given in Chapter 5 in whih the area is replaed by the eetive area and the setion modls is replaed by the eetive setion modls. The design strength o steel shold be taken as the 0. perent proo strength and the eetive ross-setional area and the eetive setion modls shold be determined in aordane with EN and EN i.e. based on the material properties at 0 C. The redtion ators or the design strength o arbon steels relative to the yield strength at 0 C illstrated in Figre C.8 may be taken rom Table C.8: - design strength relative to yield strength at 0 C: k 0.p = 0.p / y - slope o linear elasti range relative to slope at 0 C: k E =E a / E a Redtion ators or the design proo strength o stainless steels relative to the proo strength at 0 C may be taken rom Table C.9 o next Setion C..

15 C.1. MECHANICAL PROPERTIES OF CARBON STEEL Table C.8: Redtion ators or arbon steel or the design o lass 4 setions at elevated temperatres Steel Temperatre a Redtion ator (relative to y ) or the design strength o hot rolled and welded thin walled setions k 0.p = 0.p / y Redtion ator (relative to yb ) or the design strength o old ormed thin walled setions k 0.p = 0.p / yb 0 C C C C C C C C C C C C C NOTE 1: For intermediate vales o the steel temperatre linear interpolation may be sed. NOTE : The deinition or yb shold be taken rom EN

16 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Redtion ator k Slope o linear elasti range k E = E a / E a Design strength k 0.p = 0.p / y Temperatre [ C] Fig. C.8: Redtion ators or the stress-strain relationship o old ormed and hot rolled thin walled steel at elevated temperatres 374 C.. MECHANICAL PROPERTIES OF STAINLESS STEEL The mehanial properties o stainless steels are given in Annex C o EN or steel grades and Table.1 rom EN is reproded here as Table C.9 or the above ive Grades o strtral stainless steel and gives the nominal vales o the yield strength the ltimate tensile strength and the modls o elastiity. y

17 C.. MECHANICAL PROPERTIES OF STAINLESS STEEL Table C.9: Nominal vales o the yield strength y the ltimate tensile strength and Yong s modls E or strtral stainless steels aording to EN Prodt orm Type o stainless steel Grade Cold rolled Hot rolled Bars rods and Modls Hot rolled strip strip plate setions o Nominal thikness t elastiity t 6 mm t 1 mm t 75 mm t 50 mm y y y y E MPa MPa MPa MPa MPa MPa MPa MPa GPa Ferriti steel ) 450 1) 60 ) 450 ) Asteniti steels Asteniti 1) ) -erriti steel t 15 mm. t 100 mm Table C.1 rom Annex C o EN provides redtion ators relative to the appropriate vale at 0 ºC or the stress-strain relationship o several stainless steels at elevated temperatres as ollows: Slope o linear elasti range relative to slope at 0 C: k E = E a / E a - Proo strength relative to yield strength at 0 C: k 0.p = 0.p / y - Tensile strength relative to tensile strength at 0 C: k = / For the se o simple allation methods table C.1 rom EN gives the orretion ator k % or the determination o the yield strength sing: y = 0.p + k % ( - 0.p ) (C.3)

18 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL This proedre leads to an eetive yield strength whih is the stress at % total strain. k y y y For the se o advaned allation methods Table C. rom EN gives additional vales or the stress-strain relationship (see Fig. C.9) o several stainless steels at elevated temperatres as ollows: - slope at proo strength relative to slope at 0 C: k Et = E t / E a - ltimate strain: E t = tan 0.p 376 E a = tan Fig. C.9: Stress-strain relationship or stainless steel at elevated temperatres

19 C.. MECHANICAL PROPERTIES OF STAINLESS STEEL 377 Table. C.10: Parameters or deining stress-strain relationship or stainless steel at elevated temperatres Strain range Stress Tangent modls E t b a E 1 ) (1 ) (1 b b b a b a a E <.p 0 ) ( e+(d/) d Parameters = 0.p / E a Fntions b p p a E a= ) / ( ) / (1 p p a a p t E E E = b ) ( t E e = ) ( e E = e d t ) ( ) ( ) ( p t p E = e Where: is the tensile strength; 0.p is the proo strength at 0.% plasti strain; E a is the slope o the linear elasti range; E t is the slope at proo strength; is the total strain at proo strength; is the ltimate strain. Eq. (C.3) leads to 0. % % 0. 1 p y p y p p y y y k k k k k k (C.4) This eqation was sed to evalate the vale o the redtion ator or the yield strength given in the right or olmns in Table C.11.

20 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Table C.11: Redtion ators o stainless steel at elevated temperatres a [ºC] k 0.p k k % Cold rolled strip Hot rolled Hot rolled Strip plate k y Bars rods and setions 378 Grade Grade /

21 C.. MECHANICAL PROPERTIES OF STAINLESS STEEL Table C.11: Contined a [ºC] k 0.p k k % Cold rolled strip Hot rolled Hot rolled Strip plate k y Bars rods and setions Grade Grade

22 C. MECHANICAL PROPERTIES OF CARBON AND STAINLESS STEEL Table C.11: Contined Cold rolled Hot rolled Hot rolled Bars rods a [ºC] k 0.p k k % strip Strip k y plate and setions Grade When the parameters o Table C.11 are sed in the eqations o Table C.10 this an lead to a stress-strain relationship with positive rvatre; the stiness inreases or positive strains. This ors at very high temperatres (see Fig. C.10) and ths it is not generally an isse in pratial problems bt an lead to nexpeted reslts in some nmerial simlations. This problem was treated by Lopes N (009) who has proposed dierent redtion ators or the Yong s modls in the temperatre range o 1000 ºC to 100 ºC.

23 C.. MECHANICAL PROPERTIES OF STAINLESS STEEL (MPa) EN (MPa) EN E E 1 E > E Fig. C.10: Stress-strain relationship o the stainless steel at 1100 ºC 381