Att välja material till bärande konstruktioner

Transkript

1 Att välja material till bärande konstruktioner Hasse Groth & Thérèse Sterneland Avesta Research Center Outokumpu Älvsjö

2 Innehåll 1. Vad är rostfritt stål och olika typer? 2. Duplexa rostfria stål 3. Att välja material 4. Erfarenheter 10/30/2017 2

3 Vad är rostfritt stål? Järn med tillsats av minst 10.5% krom Naturligt bildad passivfilm Å = mm Självläkande Vykort passivfilm Fe + >10.5% Cr 1 mm 10/30/2017 3

4 Det finns rostfritt. och sen så finns det syrafast 10/30/2017 4

5 Olika typer av rostfria stål Kombinationen av legeringselement ger en mikrostruktur som ger vissa typiska egenskaper. Ståltillverkare gillar denna indelning! (Tillverkning Världen/Sverige) Austenitiska stål Krom + Nickel (Mo, N). Formbarhet, svetsbarhet. Vanligast. (80/70%) Ferritiska stål Krom. Magnetiskt. Vanligt förekommande. (19/1%) Duplexa stål Mycket Krom lite Ni, Mo, N. 50% ferrit-50% austenit Hög hållfasthet. Växer snabbast. (1/29%) Martensitiska stål Krom + ganska mycket kol. Ej i Eurocode Hög hållfasthet, härdbara. Knivstål. 10/30/2017 5

6 Olika typer av rostfria stål-olika egenskaper Austenitiska stål Från milda till aggressiva miljöer Ferritiska stål Lämpliga i mildare miljöer Duplexa stål Från milda till aggressiva miljöer, hög hållfasthet Martensitiska stål Lämpliga i milda miljöer där hårdhet krävs 10/30/2017 6

7 Innehåll 1. Vad är rostfritt stål och olika typer? 2. Duplexa rostfria stål 3. Att välja material 4. Erfarenheter 10/30/2017 7

8 What is Duplex Stainless Steel? Duplex stainless steel has a ferritic-austenitic microstructure The phase balance is approximately 50% ferrite and 50% austenite Duplex stainless steel combines most of the beneficial properties of ferritic and austenitic steels The duplex microstructure contributes to high strength and high resistance to stress corrosion cracking 8

9 Duplex- a long history at Outokumpu Dec 23, 1930 Seawater 453S (~ASTM 329) Brobeck cooler in grade 453 S 9

10 History Second generation Duplex Process development (AOD) made it possible to reduce the carbon content and to alloy with nitrogen. The nitrogen improved the formation of austenite after welding 2205 was invented in the 1970 s 10

11 History Third generation Duplex Super duplex Grades with Cr content 25% or more High levels of Cr, Mo, N and sometimes W give high resistance to localized corrosion Lean duplex Grades with low Ni content often replaced with Mo and N 11

12 Forta range 12

13 Product performance comparison Yield strength vs. corrosion resistance Forta range Duplex PRE = % Cr x % Mo + 16 x % N. Yield strength (R p0.2 ) uses EN minimum values for cold rolled strip 13

14 Positioning of Duplex grades An excellent combination of high strength and corrosion resistance Forta LDX 2404 Forta EDX 2304 Forta LDX 2101 Forta DX 2205 Hot coil Forta SDX 2507 Strength, R p0.2 [MPa] Duplex Austentic Forta DX 2304 Supra 316L/4404 Ultra 317L Core 304L/4307 Supra 316L/4436 Ultra 4439 Ultra 904L Ultra 654 SMO Ultra 4565 Ultra 254 SMO Corrosion Resistance, CPT typical 14

15 Duplex products HRP(P), Quarto Plate: t = 2-100* mm CPP(H), coil and plate: t = 4-10* mm CR (C), coil, strip & sheet: t = 0.1-6* mm Billet, wire rod, bar and rebar Welded tube and pipe Fittings Structural profiles - Duprof : 6 m as standard, max 13 m *Max/min. thickness grade and width dependent. 15

16 Duplex = Austenitic + Ferritic structure Ferrite Austenite Duplex 16

17 High Mechanical Strength Solid Solution hardening Atoms of another size than the pure metal is causing a disorder in the material which leads to hardening. Nitrogen is an example of a small atom that solutes between the iron atoms in stainless steels. 17

18 General characteristics of Forta range Duplex products Courtesy of Outotec. High mechanical strength (Rp min > 400 MPa) High resistance to localized corrosion (PRE 26 to 43) and stress corrosion cracking High wear resistance Low thermal expansion High energy absorption Good fabricability Cost effective and sustainable solutions 18

19 Applications: Forta range duplex Storage tanks Pressure vessels Bridge components Flexible pipes (Oil & Gas) Blast walls (Offshore) Thickeners (Mineral processing) Water gates Courtesy of IKM dsc Engineering 19

20 Innehåll 1. Vad är rostfritt stål och olika typer? 2. Duplexa rostfria stål 3. Att välja material 4. Erfarenheter 10/30/

21 Korrosionsmotstånd, några vanliga stål Outokumpu EN Struktur Cr Ni Mo N PRE* Moda ferrit Core ferrit Core austenit Core austenit Ultra 254 SMO austenit Forta LDX duplex Forta DX duplex Forta SDX duplex *PRE, Pitting Resistance Equivalent, PRE = %Cr %Mo + 16 %N PRE är ett grovt verktyg för att rangordna olika rostfria ståls motstånd mot punktfrätning 10/30/

22 Punktfrätningsegenskaper Kritisk punktfrätningstemperatur, ASTM G CPT, C Ultra 904L (1.4539) Ultra 254 SMO (1.4547) Forta LDX 2101 (1.4162) Forta DX 2304 (1.4362) Forta DX2205 (1.4462) Forta SDX 2507 (1.4410) 10/30/

23 Det finns rostfritt. och sen så finns det syrafast 10/30/

24 Urgammal tumregel: Rostfritt inomhus Syrafast utomhus 10/30/

25 Korrosivitetsklasser (ISO 9223) och erforderliga rostfria stål ISO Corrosivity Typical environments Grades C1 Very low Dry or cold zone: Central Arctic/ Antarctica and certain deserts , , C2 Low Temperate zone: rural areas and small towns. Dry or cold zone: deserts and subarctic areas. C3 Medium Temperate zone: urban areas and costal areas with low deposition of chlorides. Subtropical and tropical zone: areas with low pollution. C4 High Temperate zone: polluted urban areas, industrial areas, costal areas without spray and exposure to de-icing salts. Subtropical and tropical zone: areas with medium pollution. C5 Very high Temperate and subtropical zone: industrial areas, coastal areas and sheltered positions on coast line. CX Extreme Subtropical and tropical zone: extreme industrial areas, coastal and offshore areas , , , , , , , , , , , , , , , , , , , /30/

26 Eurocode 3: EN : /30/

27 Eurocode 3: EN /A1:2015 Corrosion Resistance Factor CRF = F1 + F2 + F3 F1 = Risk of exposure to chlorides from salt water or deicing salts; F2 = Risk of exposure to sulfur dioxide; F3 = Cleaning regime or exposure to washing by rain. 10/30/

28 EN / A1: /30/

29 10/30/

30 Effekten av ytfinhet Forta LDX 2101, 2 års exponering vid Bohus Malmön, Svenska västkusten Ra 0.2 µm Ra 0.5 µm Ra 0.8 µm Finare ytor mindre risk för initiering av korrosion Missfärgning på ytan - Estetiskt, påverkar ej hållfasthet 10/30/

31 Påverkan av atmosfären Chrysler Building, New York, byggd Paneler i typ /30/

32 Case: Gateway Arch, USA Stainless steel load bearing structure made in Arch design included load bearing, welded, stainless steel plate in grade 316 (1.4401). Inspection after 50 years Dirty, but in good shape! At that time - Minimal structural research, no duplex It was found that structural research was needed! 10/30/

33 Hur mycket rostar på ett tak i Stockholm? 1) Hur lång tid tar det innan 1 gram försvinner på en 1 m 2 yta takplåt ? (Tips: Materialet är beständigt i denna miljö. Det regnar på plåten regelbundet.) 2) En takplåt är normalt 0.5 mm tjock och väger 4 kg/m 2. Hur lång tid tar det innan 0.1 mm försvinner? Källa: Korrosionsinstitutet/KIMAB 10/30/

34 Innehåll 1. Vad är rostfritt stål och olika typer? 2. Duplexa rostfria stål 3. Att välja material 4. Erfarenheter 10/30/

35 Vanliga duplexstål i broar Forta DX 2205, Forta DX 2304, Forta LDX 2101, Forta LDX 2404, Nytt

36 Inspection of Duplex bridges To collect field experience of stainless steel bridges. Observe and record the condition and performance of various stainless steel components at site. Acknowledgement Sukanya Hägg Mameng och Jan Björk Document and inform the designers of future stainless steel structure by providing a reference point for past sucessful applications. To provide data for future design standard revisions, EN , Annex A relating to material selection.

37 Inspekterade broar CRC II, III CRC II, III CRC III Millenium, 2000 Grade Flen Bridge, 2009 Grade CRC II, III Celtic Gateway, 2006 Grade Sicklauddsbron, 2002 Grade CRC III CRC IV Zumaia, 2008 Grade UK Nynäshamn, 2011 Grade CRC II, III Spain CRC III Puerto Arrupe 2003 Grade Sölvesborg, 2013 Grade CRC II, III CRC II, III CRC IV, V Anorga, 2011 Grade Saint Fruitos, 2009 Grade Cala Galdana, 2005 Grade CRC = Corrosion Resistance Class (EN Annex A )

38 Klassningar CRC II, III CRC III CRC IV/V Low * (M > 10 km) Medium * (1 km < M 10 km) High* (0,25 km < M 1 km) Very high* (M 0,25 km) Orrhammarvägen Bridge Duplex grade years Añorga Bridge Duplex grade years Zumaia Bridge Duplex grade years Cala Galdana Duplex grade years Millenium Bridge Duplex grade years Puerto Arrupe Bridge Duplex grade years Risk of exposure to chlorides from sea salt water M=Distance from the sea Note: No information about cleaning and mainternance done was available. CRC = Corrosion Resistance Class (EN Annex A )

39 Sicklauddsbron Pedestrian Bridge General information: - Year constructed: 2002 Location: Sweden - ISO 9223 Class: C3 - Above channel, 255 ppm Cl - measured - Rain washed Materials: Forta DX 2205, beams, flange, handrail - Generally in good condition - Ra 4.0 µm 316L, end cover tube of bridge cables - Good condition, some staining due to contamination 304, brackets and stanchion - Overall in good condition but isolated pits can be observed This information is given in good faith and Outokumpu assume no liability for it 10/30/

40 Orrhammarvägen Bridge Location: Flen, Sweden Structure type: Road bridge Corrosion resistance class: CRC II, III Year of completion: 2009 (6 years) Distance from the salt water: ~60 km Local environmental notes: 8 ppm Cl- measured Longitudinal beam web Longitudinal beam flange Grade Longitudinal beam weld ER 23 7 NL Bridge bearing plate Grade Inspection date: 10/06/2015

41 Orrhammarvägen Bridge Sheltered condition Bridge beams (Ra~5.0 µm): General appearance is in good condition Sheltered condition Welded areas: Some accumulation of dirt/dust Sheltered condition Bottom of beam: Orange stain and contamination Small bolts: Poor condition. Galvanizing was visible on the bolt heads but not the shanks or nuts. Inspection date: 10/06/2015

42 Orrhammarvägen Bridge Bottom of beam: Orange stain and contamination from mild steel after the surface finishing was applied (No chloride ion was found). SEM/EDS-result Spectrum C O Mg Si K Ca Mn Fe Total Spectrum Spectrum Max Min Inspection date: 10/06/2015

43 Añorga Bridge Location: San Sebastian, Spain Structure type: Railway bridge Corrosion resistance class: CRC II, III Year of completion: 2011 (4 years) Distance from the salt water: ~ 3 km Handrail pole Handrail cable fitting Handrail tie plate Grade Arch transition structure top surface (Ra~6 µm) Grade Main arch Grade Arch transition structure side surface Grade Arch weld ER 23 7 NL Bridge beam (Ra~8 µm) Grade Inspection date: 20/10/2015

44 Añorga Bridge Main arch Arch weld Handrail pole, cable fitting and tie plate Inspection date: 20/10/2015

45 Puerto Arrupe Bridge Location: Bilbao, Spain Structure type: Footbridge / Cycleway Corrosion resistance class: CRC II, III Year of completion: 2003 (12 years) Distance from the salt water: ~10 km Local environmental notes: 2,400 ppm Cl- measured Fin Weld Fin Handrail Bridge box side surface at stair Wood Fin Bridge box side surface Bridge box fin Grade Bridge box to fin weld ER NL Bridge box side surface at stair Grade Tubular handrail Grade Inspection date: 20/10/2015

46 Puerto Arrupe Bridge Open condition Sheltered condition Sheltered condition Bridge box side surface (Ra ~4 µm), welds and fin: Good condition Bridge box surface in sheltered area: Some accumulation of dirt and staining. Discoloration is likely due to no washing, fabrication or transportation Bridge box side and fins: Orange stain Fabrication (grinding, spatter from welding). No chloride ion was observed at this point (SEM/EDS) Welds: Some scratch, dark spot from weld oxide and accumulation of dirt. Inspection date: 20/10/2015

47 Puerto Arrupe Bridge Sheltered condition Bridge box fins under surface at stair: Orange staining and discoloration Bridge box fins (Ra 4 µm): Easy to trap water and some green organic matter was growing in this area. Internal side surface and bridge box side surface at stair: Color painting to covering all scratches, vandalism, accidental contact with bicycles, dog urine, etc., Inspection date: 20/10/2015

48 Millennium Bridge Location: York, UK Structure type: Pedestrian bridge Corrosion resistance class: CRC II, III Year constructed: 2000 (15 years) Distance from the salt water: ~60 km Local environmental notes: 20 ppm Cl- measured Bridge arch (Ra ~0.3 µm) Bridge deck kurb Balustrade handrail Inspection date: 17/08/2015 Balustrade infill framing Balustrade stanchion Painted carbon steel Handrail Cable fitting and bolt Suspension cable

49 Millennium Bridge Open condition Sheltered condition Arch (Ra ~0.3 µm): Discoloration is more related to birds (some bird droppings) that evidently perch on the arch. No corrosion was observed. Junction between arch and deck: Stain was noted Cable: Good condition with some staining and debris were observed. Handrail design: Easy to trap water and some green organic matter was growing in this area. Mesh frame (Ra~ 0.3 µm) and Infill mesh: Good condition Inspection date: 17/08/2015

50 Millennium Bridge Handrail (circular section): Good condition Stanchions - vertical direction: Some staining Horizontal direction (Ra~2.5 µm): Some staining Painted carbon steel Fin at the northwestern side: Orange staining consistent with contamination from mild steel. No evidence of structurally concerning corrosion. Inspection date: 17/08/2015

51 Zumaia Bridge Location: Zumaia, Spain Structure type: Footbridge Corrosion resistance class: CRC III Year of completion: 2008 (7 years) Distance from the salt water: ~1 km Local environmental notes: 15,200 ppm Cl- measured Inspection date: 20/10/2015

52 Zumaia Bridge Fiber glass Handrail Wood Bridge beam (Deck facing surface) Grade Bridge beam Grade Checker plate flooring Grade Weld (Ra ~ 4 µm) Weld Balustrade top surface Grade Weld ER NL Balustrade infill bracket Grade Bolt head Grade Balustrade end plate Grade Weld ER NL Stiffening angle under handrail Grade Handrail extension plate Grade Inspection date: 20/10/2015

53 Zumaia footbridge Bridge beam Bridge beam Bridge beam (Deck facing surface, Ra~4-5 µm) Weld Balustrade top surface (Ra~5-6 µm) Weld Weld General appearance to be in good condition. No chloride ion (SEM) was found on the surface. Staining and discoloration was observed on the surface. No corrosion attack were observed Inspection date: 20/10/2015

54 Zumaia footbridge Balustrade top surface and end plate: Orange stain Fabrication (grinding) of carbon steel fence (handrail) beside the bridge Weld oxide and heat tints Orange stain on the dome nuts and under crevice area. Inspection date: 20/10/2015

55 Cala Galdana Bridge Location: Menorca, Spain Structure type: Road and foot bridge Corrosion resistance class: CRC IV/V Year of completion: 2005 (10 years) Distance from the salt water: < 250 m Local environmental notes: 17,300 ppm Cl- measured Inspection date: 22/10/2015

56 Cala Galdana Bridge Balustrade staunchion (Bracket plate and plate) Balustrade infill tube and hand rail Grade Bridge deck main beam Bridge deck outrigger beam Grade Main bridge arch weld ER NL Bridge arch Grade Bridge arch infill plate Grade Vehicle barrier to arch transition ER L Bolt and nut Galvanized steel Vehicle barrier tube Bracket base plate Plate Grade Vehicle barrier bracket weld ER NL Inspection date: 22/10/2015

57 Cala Galdana Bridge Weld Infill plate (Ra ~4-5 µm) Weld Weld Main bridge arch, infill plate and weld: General appearance to be in good condition Balustrades (Ra 3-6 µm): Grey staining and discoloration was observed on the surface. Inspection date: 22/10/2015

58 Cala Galdana Bridge Sheltered condition Sheltered condition Sheltered condition Bridge deck: Good condition. Staining from water run off Fabrication: Some weld spatter was observed but did not cause any corrosion Fabrication: Orange staining at creviced associated with weld joint between two tubes Bolt and nut: Red rust and corrosion Inspection date: 22/10/2015

59 Cala Galdana Bridge Galvanized steel ER L ER NL Inspection date: 22/10/2015

60 Sölvesborg Pedestrian and Cycle Bridge General information: - Year constructed: 2013 Location: Sweden - ISO 9223 Class: C2 - Saline Bay, 3997 ppm Cl - in the water - Corrosion resistance class II or III in general depending on frequency of rain washing Materials: Forta LDX 2101 on arch - Generally in good condition - Ra 3.0 µm 316L hand rails, cable fittings - Some orange staining from contamination - Ra 3.0 µm This information is given in good faith and Outokumpu assume no liability for it 10/30/

61 Resultat Det allmänna intrycket från inspektionerna är att broarna är i generellt gott skick. De flesta anmärkningarna kommer från kontaminering, fabrikation, transport eller dagligt bruk. Fel: Kolstålsavskrap, kapskivesprut, svetssprut, dåligt betade svetsar, kolstålsskruvar, fel stålsort Inget som påverkar funktionen. Materialvalen som gjorts i dessa fall kan bedömas som rätt och överenstämmer i princip med Eurocodereglerna.

62 Tack för uppmärksamheten! 10/30/