High Strength Steel for Steel Constructions Ronny Willms AG der Dillinger Hüttenwerke 03.12.2009 Dillinger Colloquium Constructional Steelwork 1
CONTENT Introduction Delivery Conditions -AR -N / NE -Q + T - Advantages of -Processing - Economics Examples 03.12.2009 Dillinger Colloquium Constructional Steelwork 2
Introduction High strength steel What s that? End of 1920: Introduction of the steel grade St52 (S355) for bridge-building (Prof. Klöppel) St52 was called a high strength steel for a long period Now: S355 is a standard material for bridge-building Definition of high strength depends on the technical developement Today s Definition: high strength steel Steel with R eh > 355 MPa 03.12.2009 Dillinger Colloquium Constructional Steelwork 3
Introduction High strength steel Weight reduction Economical processing 03.12.2009 Dillinger Colloquium Constructional Steelwork 4
Introduction Coking plant Blast furnaces Ingot casting Sintering plant Steel mill Desulphurisation Converter Vacuum treatment Continuous casting Rolling mill 03.12.2009 Dillinger Colloquium Constructional Steelwork 5
Introduction Coking plant Blast furnaces Ingot casting Sintering plant Steel mill Desulphurisation Converter Vacuum treatment Continuous casting Rolling mill 03.12.2009 Dillinger Colloquium Constructional Steelwork 6
Delivery Conditions DELIVERY CONDITIONS AR Q+T N 03.12.2009 Dillinger Colloquium Constructional Steelwork 7
Delivery Conditions 03.12.2009 Dillinger Colloquium Constructional Steelwork 8
Delivery Conditions AR hot rolling 03.12.2009 Dillinger Colloquium Constructional Steelwork 9
Delivery Conditions AR As Rolled T Classical rolling Normalising Transition area: α-fe - γ-fe Cooling on calm air 03.12.2009 Dillinger Colloquium Constructional Steelwork 10 t
Delivery Conditions N hot-rolling + Normalising 03.12.2009 Dillinger Colloquium Constructional Steelwork 11
Delivery Conditions N Normalising T Classical rolling Normalising Transition area: α-fe - γ-fe Cooling on calm air Cooling on calm air 03.12.2009 Dillinger Colloquium Constructional Steelwork 12 t
Delivery Conditions N Normalising rolling T Phase 1 Phase 2 (T > 900 C) Waiting time Transition area: α-fe - γ-fe Definition: After an additional normalising in the furnace, the properties of a normalised rolled plate must fulfil the mechanical requirements of the standard. Cooling on calm air t 03.12.2009 Dillinger Colloquium Constructional Steelwork 13
Delivery Conditions Q+T hot-rolling Quenching + Tempering 03.12.2009 Dillinger Colloquium Constructional Steelwork 14
Delivery Conditions Q+T Quenching + Tempering T Classical rolling Quenching Tempering core surface 03.12.2009 Dillinger Colloquium Constructional Steelwork 15 t
Q+T [ C] 1390 Effect of quenching Carbon solved in the lattice Austenite Delivery Conditions 910 Ferrite + Cementite (Carbon can leave the lattice) Martensite (Carbon stays in the lattice, distorted structure) slow cooling: Ferrite + Perlite fast cooling: Martensite 03.12.2009 Dillinger Colloquium Constructional Steelwork 16
Delivery Conditions Q+T Effect of tempering Charpy-V [J] 250 200 150 100 50 A4 A3 A2 A1 quenched 0-120 -100-80 -60-40 -20 0 Temperature [ C] 03.12.2009 Dillinger Colloquium Constructional Steelwork 17
Delivery Conditions Q+T Effect of tempering 1400 1300 Yield point Ultimate stength Strength [MPa] 1200 1100 1000 900 800 700 quenched A1 A2 A3 A4 Temper-Parameter 03.12.2009 Dillinger Colloquium Constructional Steelwork 18
Delivery Conditions Q+T Typical applications 03.12.2009 Dillinger Colloquium Constructional Steelwork 19
Delivery Conditions ThermoMechanical rolling 03.12.2009 Dillinger Colloquium Constructional Steelwork 20
Delivery Conditions Thermomechanical rolling T Phase 1 Phase 2 (T > 900 C) Phase 3 (T > 700 C) Waiting time Waiting time Accelerated cooling with water (ACC) Cooling on calm air 03.12.2009 Dillinger Colloquium Constructional Steelwork 21 t
Delivery Conditions Thermomechanical rolling γ (coarse) γ (fine) recrystallised γ (fine) formed α Heating Grain refinement TEMPERATURE Final rolling Cooling on air Accelerated cooling Tempering TIME 03.12.2009 Dillinger Colloquium Constructional Steelwork 22
Advantages of -steel - Processing PROPERTIES OF -steel: Fine grain High toughness Low carbon content Low preheating temperatures Excellent WELDABILITY 03.12.2009 Dillinger Colloquium Constructional Steelwork 23
Advantages of -steel - Processing Fine grain Normalised (air) (ACC) Hall-Petch: Grain size Strength Toughness + Excellent weldability 03.12.2009 Dillinger Colloquium Constructional Steelwork 24
Advantages of -steel - Processing High toughness / High safety 350 300 250 S355J2+N S460ML S690QL Charpy-V [J] 200 150 100 50 0-120 -100-80 -60-40 -20 0 20 Temperature [ C] 03.12.2009 Dillinger Colloquium Constructional Steelwork 25
Advantages of -steel - Processing High toughness / High safety Charpy-V [J] 350 300 250 200 150 100 50 S355J2+N S460ML S690QL 0-120 -100-80 -60-40 -20 0 20 Temperature [ C] Welding leads to toughness reduction High toughness in the base material reduces the risk of brittle fracture and gives saftey! 03.12.2009 Dillinger Colloquium Constructional Steelwork 26
Advantages of -steel - Processing High toughness / High safety Example: Ilverich Rhine Bridge (Germany) DI-MC 460 with a thickness up to 100 mm Charpy tested at - 80 C 03.12.2009 Dillinger Colloquium Constructional Steelwork 27
Advantages of -steel - Processing Low carbon content S 460 NL S 460 ML acc. Auxiliary acc. Auxiliary EN 10025-3 Data EN 10025-4 Data C < 0,20 0,17 < 0,16 0,09 Si < 0,60 0,45 < 0,60 0,30 Mn 1,00-1,70 1,65 < 1,70 1,50 P < 0,030 0,015 < 0,030 0,011 S < 0,025 0,010 < 0,025 0,005 Nb < 0,05 - < 0,05 < 0,04 V < 0,20 0,17 < 0,12 < 0,05 Mo < 0,10 - < 0,20 - Ni < 0,80 0,29 < 0,45 0,25 CE 0,50 0,39 Pcm 0,29 0,20 CET 0,34 0,28 Carbon equivalents: Plate thickness 50 mm CE = C + Mn/6 + (Cr + Mo + V)/5 + (Ni+Cu)/15 Pcm = C +Si/30 + (Mn + Cu + Cr)/20 + Ni/60 + Mo/15 + V/10 + 5B CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40 03.12.2009 Dillinger Colloquium Constructional Steelwork 28
Advantages of -steel - Processing Low preheating temperatures EN 1011-2 Recommendations for arc welding of ferritic steels T p = 697 CET + 160 tanh d 35 + 62 HD 0.35 + ( 53 CET 32) Q 328 T p - Preheating temperature [ C] CET - Carbon equivalent [%]: CET = C + (Mn + Mo)/10 + (Cr + Cu)/20 + Ni/40 d - Plate thickness [mm] HD - Hydrogen content [cm³/100 g] Q - Heat input [kj/mm] Preheating is necessary to avoid: Preheating is necessary to avoid: excessive hardening cold cracking 03.12.2009 Dillinger Colloquium Constructional Steelwork 29
Advantages of -steel - Processing Low preheating temperatures Hydrogen content of welding consumable [cm 3 /100g] 10 8 6 4 2 S355M 25 C 50 C 75 C typisc her Bereich für H2 Gehalte 0 0 20 40 60 80 S460M 25 C 50 C 75 C 100 C typischer Bereich für H2 Gehalte 0 20 40 60 80 0 10 8 6 4 2 Hydrogen content of welding consumable [cm 3 /100g] Plate thickness [mm] Plate thickness [mm] Calculated with Q = 2.5 kj/mm (submerged arc welding) and for typical CET s 03.12.2009 Dillinger Colloquium Constructional Steelwork 30
Advantages of -steel - Economics Cost efficiency Low preheating 1. Reducing preheating temperatures Gas consumption Heating time 2. Avoiding preheating No installations No setting up time No gas 03.12.2009 Dillinger Colloquium Constructional Steelwork 31
Advantages of -steel - Economics Cost efficiency Low preheating Often underestimated, but worth to think about 1. Reducing preheating temperatures Gas consumption Heating time 2. Avoiding preheating No installations No setting up time No gas 03.12.2009 Dillinger Colloquium Constructional Steelwork 32
Advantages of -steel - Economics Cost efficiency Low preheating Often underestimated, but worth to think about 1. Reducing preheating temperatures Gas consumption Heating time 2. Avoiding preheating No installations No setting up time No gas Biggest potential for saving costs 03.12.2009 Dillinger Colloquium Constructional Steelwork 33
Advantages of -steel - Economics Cost efficiency Low preheating t 1 t 1 = t 2 S355NL changing delivery condition Possibility to avoid preheating! no gas consumption no set-up times higher capacity in the work shop t 2 S355ML 250 200 EN 1011-2: T pcet = 750 x CET 150 0.01% CET ca. 7.5 C T p CET [ C] 150 100 50 0-50 0,2 0,3 0,4 0,5 Carbon equivalent CET [%] 03.12.2009 Dillinger Colloquium Constructional Steelwork 34
Advantages of -steel - Economics Cost efficiency Low preheating Sauertal Bridge (Germany) Box-girder-bridge Length: 1195 m Width: 27 m 11 Spans: 75 150 m Tonnage: 13,000 t Grade: S355J2+N 3000 t > 25 mm thickness 03.12.2009 Dillinger Colloquium Constructional Steelwork 35
Advantages of -steel - Economics Cost efficiency Low preheating Alternative: S355J2+N > S355M No preheating Conditions: 30,000 h welding time 15 % for preheating 50 /h labour costs A) Saving preheating times B) Additional costs S355M (25 /t) BENEFIT A = 30,000 h x 15 % x 50 /h B = 3,000 x 25 /t C = A - B 225,000 75,000 150,000 03.12.2009 Dillinger Colloquium Constructional Steelwork 36
Advantages of -steel - Economics Cost efficiency Low preheating Low preheating temperatures are not only a matter of costs! Also in terms of job safety, low preheating temperatures are beneficial! NO HOT SURFACES / NO HANDLING WITH GAS / BETTER WORKING CONDITIONS 03.12.2009 Dillinger Colloquium Constructional Steelwork 37
Advantages of -steel - Economics Cost efficiency High strength t 1 t 2 < t 1 t 2 S355NL fy = 315 Mpa increasing yield strength S460NL Weight reduction Bigger assembling units possible Less holding times in the workshop Less welding consumables Reduction of welding time Reduction of testing time t t A A,B ~ t 2 Welding costs ~ t² Plate thickness 03.12.2009 Dillinger Colloquium Constructional Steelwork 38
Advantages of -steel - Economics Cost efficiency High strength 100 mm 73 mm 73 mm S355NL fy = 315 Mpa increasing yield strength S460NL changing delivery condition S460ML Weight reduction (ca. 30%) Bigger assembling units possible Less holding times in the workshop Less welding consumables Reduction of welding time Reduction of testing time Avoiding/Reducing preheating Better weldability High toughness reserves => High safety 03.12.2009 Dillinger Colloquium Constructional Steelwork 39
Choosing the right steel Strength Delivery Toughness condition 03.12.2009 Dillinger Colloquium Constructional Steelwork 40
Choosing the right steel Strength Delivery Toughness condition 03.12.2009 Dillinger Colloquium Constructional Steelwork 41
Reference Projects Airbus-Hangar (Frankfurt / M.) - -Steel S460ML - constant yield strength up to 120 mm 03.12.2009 Dillinger Colloquium Constructional Steelwork 42
Reference Projects World Financial Center (Shanghai) - -Steel S460M - thickness up to 100 mm - constant yield strength 03.12.2009 Dillinger Colloquium Constructional Steelwork 43
Reference Projects Øresund Bridge (Denmark-Sweden) - -Steel - S460M/ML up to 80 mm 03.12.2009 Dillinger Colloquium Constructional Steelwork 44
Thank you for your attention! 03.12.2009 Dillinger Colloquium Constructional Steelwork 45