prof. priit kulu. 2 outline 1. high-strength structural steels 2. high-performance tool steels 3....

Prof. Priit Kulu

2 Outline 1. High-strength structural steels 2. High-performance tool steels 3. Metallic-ceramic materials 4. Light-weight metals and alloys 5. Superalloys Advanced metallic materials 2

3 3 Metallic materials with superior properties Superconductive NbTi, Nb 3 Sn, Nb 3 Ge Structural alloys Neodymium rare-earth magnets (alloys of Nd, Fe and B) are strongest known permanent magnets. Sm-Co magnets Mg- and Al-alloys with superior properties, Al-metaglass, foams Ti-alloys with thermomechanical properties, superalloys, maraging steels, intermetallides, high-density alloys, shape-memory alloys Biocompatible Ti-alloys Amorphous alloys with chemical and thermal properties, Ni- and Fe aluminates

4 Strength groups of materials Classification based on tensile strength (R m ) of materials I. Low-strength ( < 250 N/mm 2 ) II. Mid-strength (250...750 N/mm 2 ) III. High-strength (750...1500 N/mm 2 ) IV. Ultrahigh-strength (

5 Production technologies of hihg-strength steels and alloys Advanced metallic materials 5

6 1. High-strength structural steels 2. High-performance tool steels 3. Metallic-ceramic materials 4. Light-weight metals and alloys 5. Superalloys Advanced metallic materials 6

7 High-strength steel... what is it? The end of 1920-s Steel St 52 (S355) for bridge construction Today S355 is standard grade Definition for high-strength is dependent on level of development. Steel R eH > 355 MPa 7 Advanced metallic materials

8 Alloying of ferrite Hardening Ageing Alloying elements, % Ageing time, t Methods for increasing strength 1. structure refinement 2. alloying B; microalloying elements Nb, Ti, V and N 3. low carbon steels transgranular fracture 4. two- and multi-phase structures F+M; F+M+B 5. dispersion strengthening micro- and nanosteels 6. deformation hardening: - low- & high-temperature - isothermal - marforming Advanced metallic materials

9 Heat treatable boron-steels 0,003% of B increased through-hardenability 0,002...0,003% of B in solid solution has the same effect on hardenability than 0,7% Cr; 0,5% Mo or 1% Ni Through-hardenability diameter up to 200 mm C24CR R p0,2 1000; R m 1500; A 7% 9 Advanced metallic materials

10 Low-alloy high-strength steels Also known as HSLA steels C = 0,2..0,3% ; alloying el: Mn, Si Micro alloying with Nb, Ti and/or V dispersion strengthening + grain refinement HX340LAD HX460LAD R p0,2 560; R m 640 N/mm 2 ; A min 15% 10 Advanced metallic materials

11 Two- and multi-phased steels Also known as duplex (DP) and complex (CP) steels Ultra-High-strength (UHS) ductile steels - Two-phase LITEC DP R p0,2 750 N/mm 2 ; R m 980 N/mm 2 ; A min 10% 11 Advanced metallic materials

12 good formability and high strength ability of high energy absorption high strain-hardening rate good fatigue strength DP-steelCP-steel 12 Advanced metallic materials - Multi-phase LITEC CP R p0,2 900; R m 980 N/mm 2 ; A 7%

13 Maraging (martensite-ageing) steels (1) Martensitic steels ( C%) - low ductility and toughness in case of high R m - M decomposition, formation of carbide phase brittleness Maraging steels in 1980 - low C-content ( 0,03%) transgranular fraction - alloying el. Ni (17...25%), Mo + Ti, Al, Ta etc. Quenching C-free martensite, Ageing intermetallides (4 5) nm, (NiTi, Ni 3 Ti, NiAl, Ni 3 Mo etc.) R m 2000 N/mm 2, R p0,2 1500 N/mm 2, A = 10 - 12% 13 Advanced metallic materials

14 Maraging steels (2) 14 Advanced metallic materials

15 Termomechanically processed / deformation hardened 15 Advanced metallic materials high temperaturelow temperature isothermalmarforming

16 Thermomechnical rolling

17 TRIP-steels (Transformation Induced Plasticity) Low alloy steels (car industry) 0,2 0,3 % C; 1,5 2,0 % Mn, Si + Al High alloy Ni-Cr steeks 0,2 0,3 % C; 8 32 % Ni; 8 14 % Cr+Mn (0,5 2,5%), Mo, Si Quenching (985 1200 C) F, B, A Deformation (< T recr = 250 550 C), A M R m 1700, R p0,2 1550, A =50 60 %, K IC, -1

18 Strength-plasticity of high-strength steels TMT + def. ageing KTMT TMT + def. ageing Low-alloy steels Maraging steels (high- alloy) R p0,2 N/mm 2 2000 1000 204060 A% TRIP-steels

20 Advanced tool steels (1) I generation of high-speed steels (HSS) carbide temper hardness steels 500 - 650 0 C, e.g. HS 6 5 2 5 W-Mo -V Co Intermetallic temper hardness steels 650 - 750 0 C, Co 7 W 6, (CoFe) 7 W 6 etc. (11 20%)W; 7% Mo; (1-3%)V; (20 25%)Co Structure (cast and rolled) 20 Advanced metallic materials

21 Advanced tool steels (2) II generation of high-speed steels PM steels (PM/HIP) Uddeholmi steels Vanadis 4, 6, 10, 23, 30, 60 (Super Clean) (1,3 - 2,9%) C; 6,5 W; (1,5 - 7%) Mo; (3,1 - 9,8%) V; 10,5% Co Structure (PM / HIPed) 21 Advanced metallic materials

22 Advanced tool steels (3) III generation of high-speed steels Sprayformed, SF + HIP PM steels, Vanadis 4 EXTRA WEARTEC 2,8 C; 8,9 V; 7,0 Cr; 2,3 Mo; Si; Mn ROLTEC 1,4C; 4,6Cr; 3,7 V; 3,2 Mo; Si; Mn TOUGHTEC 1,6C; 7,2V; 5,0 Cr; 2,3 Mo; Si; Mn 22 Advanced metallic materials

23 SF /HIP Similar to PM/HIP, slab formation by spraying methods 23 High-Tech Materials & Technologies

24 Strength of high-speed steels TRZ, GPa Diameter of carbide particles, m 24 Advanced metallic materials

26 Classification of wear resistant materials depending on volumetric content of hard phase Advanced metallic materials 26

27 Metallic-ceramic composites Carbide steels and alloys Ferro-TiC Steel (50 - 70)% -TiC Double-reinforced MMC (Cr-steel + 20%VC) + 20%WC Self-fluxing alloys NiCrSiB + 50% (WC-Co) Ceramic/metallic TiC-NiMo (50 - 60)% (NiMo)(2:1) 920 1620 HV10 Cr 3 C 2 -NiCr (50 - 60)% NiCr 27 Advanced metallic materials

29 Light-weight materials Mg alloys Mg-alloys (Mg: = 1740 kg/m 3, T s 649 0 C) Alloying elements: Al (3 - 10%); Zn, up to (5 6%); Mn; Zr R m 300 N/mm 2 (deformable alloys)R m / 20 220 N/mm 2 (cast alloy) 29 Advanced metallic materials

30 Light-weight materials Al alloys Al-alloys Al-Li alloys (Li is only dopant, which R m, E, however = 2500 kg/m 3 ) 2Li, 4Mg, R m = 220 350; R p0,2 = 135 210 N/mm 2 Powder-aluminum-alloys - dispersion strengthened Al-alloys (SAP-Al 2 O 3 15%, Al- C-alloys Al 4 C 3 20 volume%), allowed working temperature up to 550 0 C Foam-aluminum ( ~ 200 kg/m 3 ) 30 Advanced metallic materials

32 Superalloys alloys capable of service at high temperatures, usually above 1000 C heat-resistant high-temperature strength alloys Ni-alloys Co-alloys heat resistance (oxidation resistance > 600C) refractory steels = heat res. + high temp. strength 32 Advanced metallic materials

33 Ni-alloys Ni uses: ca 60% stainless steels 12% Ni-alloys 10% coatings 10% alloy steels Heat resistant alloys ( s uperalloys) wrought (Inconel Ni 20-23 Cr; Hastelloy Ni- 7-22 Cr-Co) cast ( polycrystalline, directionally solidified, single crystal) PM (HIP-ed, IN 100, Rene 95 gasturbine disk) 718 (cast) Ni (4,75 5,5%) Nb aerospace, nuclear structural applications (-250 +700 C). MA 754 PM/HIP Ni 1% Y 2 O 3 33 Advanced metallic materials

34 Co-alloys Co uses: ca46% superalloys 15% steels 10% cemented carbides Wear resistant alloys Stellite Co (10 30%); Cr (1,5 22) Ni; up to 15% W; 1 Mo Heat resistant alloys wrought Co + (20 30%) Cr; (14 15%) W cast Co +(23 29%) Cr; (1 10 %) Ni; 7 W Corrosion resistant alloys Ultimet Co + 26Cr; 9Ni; 5Mo; 2W 34 Advanced metallic materials

35 General stress-rupture behaviour of superalloys

36 TUT materials engineering web-site: www.ttu.ee/mti [email protected]

prof. priit kulu. 2 outline 1. high-strength structural steels 2. high-performance tool steels 3....

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