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Lecture 1.1 metals and it’s alloys. their crystalline structure and properties


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  • 1. Metals and Its Alloys, their crystalline structure and properties By: M. Sc. Arnaldo Valdés Carrazana. WEB: Email: Knowing the world of metals and alloys means create solutions!
  • 2. OBJECTIVES • To analyze the most common alloys used in engineering. • To explain the influence of the crystalline structure and the grains in the final properties. • To explain the main tests to obtain the mechanical properties. • To familiarize with the classification of steels and its nomenclature according to AISI , SAE and European codes.
  • 3. Pure Metals in the Periodic Table.
  • 4. Materials Classification Chart Pure Metals and their Alloys Ferrous = (Base Iron) • Pure Iron (Fe). • Steels (Fe+C where C<1.7%) • Cast Iron (Fe+C where C 1.7%) Nonferrous = (No Iron) • Aluminum (Al) and its alloys (Silumin and Duralumin) • Copper (Cu) and its alloys (Brasses and Bronzes) • Nickel (Ni) and its alloys • Precious metals (Au, Ag) • Refractory metals (Nb, Mo, Ta, Ti). Polymeric •Thermoplastics •Thermoset •Elastomers Ceramic •Glasses •Ceramics •Graphite •Diamond Composite •Reinforced plastics •Metal-matrix composites •Ceramic-matrix composites •Sandwich structures •Concrete Metal: any of several solid mineral elements (such as iron, gold, silver, copper, etc.) that are malleable under heat or pressure and can conduct heat and electricity; element yielding positively charged ions in watery solutions of its salts. Ferrous, is an adjective used to indicate the presence of iron. The word is derived from the Latin word ferrum (iron). Ferrous metals include steel, cast iron (Alloys Fe+C) and alloys of iron with other metals (such as stainless steel). Non-ferrous is used to indicate metals other than iron and alloys that do not contain an appreciable amount of iron. Alloy: The mix of two or more substances where at least one of them is a metal. For example Steels, Cast Iron, Silumin, Duralumin, Brass, Bronze, etc. Pure metals have not practical use in industrial applications due the low properties.
  • 5. Brief Comparison Ferrous Alloys (Base Fe) • Magnetic (Because the Iron presence) • Heavy (Density=7.85g/cm3) • Superficial Rust • Color Dark Brown • • • • Non Ferrous Alloys (Base Al, Cu, etc.) Non Magnetic Light No Superficial Rust Color (Gray, Silver, Yellow, Orange)
  • 6. Identification of metals and Alloys
  • 7. Internal structure. • Macrostructure: Naked eye or low magnification. • Microstructure: Optical Microscope (400-1500x) • Substructure: Electron Microscope (Scanning or transmission) up to 1000000x • Crystal Structure: X-ray Diffraction • Electron structure: Spectroscope • Nuclear structure: Nuclear Magnetic Resonance (NMR)
  • 8. Crystalline microstructure in Pure Metals. Crystalline structure is a result of the an arrangement of atoms during the solidification process. a. Simple cube (SC) b. Body Centered cube (BCC) c. Face Centered Cube (FCC) Note: In some metals and its alloys this structure changes not only during the cooling process, and the final structure depends on the cooling rate determining its final properties. For example Fe and Steels.
  • 9. Stages during the Solidification in metals. 1. Nucleation: It begins at foreign particles in melt. 3. Grain Formation: Interface develops. 2. Crystal growth: Crystals begin to grow from each. 4. Polycrystalline structure: Grain growth is limited by another grain, creating a boundary between them
  • 10. Crystalline Structure of Pure Metals. All atoms are held in place by electromagnetic forces. If an external force is applied the crystalline network can be broken if such force is higher than the Yield Strength (YS). A low strength level only cause a temporal deformation called (elastic deformation). A higher strength lever (higher than the Yield Strength of the material will cause permanent deformation called (plastic deformation) by breaking the bunds between atoms.
  • 11. Crystalline Structure of Alloys. The crystalline structure of an alloy will be reinforced by the presence of foreign atoms. This explains why in Industrial applications Pure metals are not used. In other words a particular alloys (Example Steel) is stronger than the pure metal (Fe).
  • 12. Metal Properties Mechanical Properties • Traction • Compression • Bending Impact (Toughness) Technological Properties Hardness •Brinell (HB) •Rockwell (HR) •Vickers (HV) • • • • Weldability Machinability Malleability Corrosion Resistance Physical Properties • • • • • • Melting Point (Tm) Density ( ) Thermal conductivity ( ) Specific heat (C ) Electrical resistivity ( ) Magnetic permeability ( )
  • 13. Technological Properties: Are those properties in relation with the Manufacturing Processes or Service. The valuation is usually qualitative (Good, Regular, Bad). Quantitative Methods also can be used. • Weldability: The ability of an alloy to be welded well, using simple procedures. • Machinability: The ability to make parts using machining cutting tools. • Malleability: The ability of the metal to keep the shape after the deformation without cracking in the edges.
  • 14. Strength-Strain Diagram obtained from the Traction Test. (MPa) TS (MPa STEELS Uniform Elongation ) Neckin g Al, Cu and its Alloys T S Fractur e YS0. Y S e p 2 σ=E*δ 0.2 % elastic Eng. Symbol plastic Parameter name δ (%) ISO Symbols p Elastic Limit Lower Yield Strength Rp Coupon Test L -l l = 1 0 l0 l0 δ = d0 d0-d1 d1 Re y USA Symbols Proportional Limit e Ys y0.2 Conventional Yield Strength Rp0.2 Ys0.2 t= u δ δ (%) Ultimate Tensile Strength Rs UTS or TS Relative Strain (Elongation) A δ Poisson’s ratio (Estriction) Z = d0 l0 l1 1MPa=10.19 kg/m2=145.04 psi
  • 15. Typical values of Ultimate Tensile Strength, Yield Strength and Elongation. Metal or Alloy TS (MPa) Ys (MPa) 1725 205 65-2 185-285 40-200 60-3 90 35 45 90-600 35-550 45-4 220 70 45 140-1310 76-1100 65-3 320 58 30 Nickel Alloys 345-1450 105-1200 60-5 Titanium 275-690 140-550 30-17 Titanium Alloys 415-1450 344-1380 25-7 Molybdenum Alloys 90-2340 80-2070 40-30 Magnesium 160-195 90-105 15-3 Steels Iron Aluminum Aluminum Alloys Copper Copper Alloys Nickel δ- (%) Magnesium Alloys 240-380 130-305 21-5 Note: (MPa “Mega Pascal” is the unit of strength in International System and psi “pound per square inches” in Imperial System)
  • 16. How to choose the filler metal for welding? The strength of the weld (Filler Metal) during fusion welding, should be equal or higher than the metal to weld on (Base Metal) TSFM ≥ TSBM This cannot be possible only during Brazing or Soldering since the nature of both FM and BM are not the same. (MPa) TSFM TSBM YS δ (%)
  • 17. Coupon Test for Impact. 10mm Pendulum Impact 10mm U or V notch
  • 18. Hardness Test. Note: Hardness is important for elements of machines, not for structures or other. a. Brinell Method. Applied Force Coupon Test Indenter D Di b. Rockwell Method.
  • 19. Physical Properties of several Metals and Alloys. Metal or Alloy Density ( ) (kg/m3) Thermal conductivity Melting point (Tm) ( ) (⁰C) W/(m·K) (t=20⁰C) 2712 204 659 Aluminum alloys 7700 - 8700 120 - 180 462-671 Brass - casting 8400 - 8700 Aluminum 990 - 1025 Red Brass 8746 159 1027 Yellow Brass 8470 115 930 Bronze - lead 7700 - 8700 850 - 1000 Copper 8930 385 1083 Gold 19320 318 1063 6800 - 7800 72 1530 Pure iron Cast Iron 7850 Wrought Iron 7750 58 Gray (1370), Malleable 1360, White (1370) 1450 Lead 11340 35.3 327 Nickel 8800 89 1453 Silver 10490 406 961 Solder 50/50 Pb Sn 8885 Non alloyed and low alloy steel 7850 53.6 1480 7480 - 8000 12.11 - 45.0 1430-1500 Tin 7280 63 232 Zinc 7135 115 419 Stainless Steel
  • 20. Procedure for Calculation of Weight. V: Volume (cm3) : Specific Weight (g/(cm3) A: Cross Sectional Area (cm2)
  • 21. Examples. Example 1: In a workshop there are 4 cranes (0.5Tn, 1.3Tn, 4Tn and 7Tn). Which one cannot be use for lifting a steel slab with dimensions (4000x1000x40mm)? Solution: Calculating the weight of a steel slab: Weigh (W)=Volume (V)*(Density) W=(4M*1M*0.04M)*7850Kg/M3=1256kg=1.3Tn Consequently cranes for (0.5 and 1.3) shouldn’t be used to lift the slab. Example 2: Find out the weight of a similar slab made out of Aluminum. W=(4M*1M*0.04M)*2712Kg/M3=433kg=0.4Tn This can be lift with the (0.5Tn crane). Example 3: How many times steel weigh more than Aluminum? Solution: 7850/2712=2.89=2.9 times.
  • 22. Steels Classification Chart Steels = Fe + C where (C ≤ 2.14%) Non Alloy Steels (Plain Carbon) Steels Low Carbon C < 0.3% Alloy Steel Low Alloy ∑AE < 5% Several types Si, Si-Mn, etc Cr-Mo Medium Carbon 0.3% ≤ C < 0.5% Medium Alloy 5%≤ ∑AE <10% Ni (cryogenic) High Carbon 0.5% ≤ C < 1% Ultra High Carbon 1.0% ≤ C ≤ 1.7% Cr-Mo-V Ni (Maraging) High Alloy ∑AE ≥ 10% Cr-Ni (Stainless Steel Cr 12%) Mn (Hadfield) Mild Steel: Non Alloy and low carbon steel with C from 0.16 to 0.29%, which is used in 85% of all steel applications in the world.
  • 23. Application of Alloys • Structures: Bridges, Buildings, Decks, Cranes, Pipelines, Vessels, etc. • Elements of Machines: Pistons, Bearings, Shaft, Levers, etc. Parts that move. • Devices: Appliances, Power tools, Furniture, and other. • Tools: Pliers, Screwdrivers, etc. • Other: Pipes, Tubes, Fittings, Cables, etc.
  • 24. Type of alloy Grade Criteria of use Type of supply Examples Good Weldability Good Malleability Good Machinability Bars, Flats, Sheet Metal, Beams, Pipes Structures; Elements of machines were hardness is not an issue. Devices For manufacturing Elements of machine. For Machining + Heat Treatment to change superficial hardness. Regular Weldability (Not for manufacturing welding) Bars Elements of Machines where hardness is important. HCNA C≤0.5% To withstand deformation and wearing. Bad Weldability (Not for welding at all) Bars Tools Springs LCLA C<0.3%; ∑AE<5% Similar to LCNA but more Tensile strength, Resistant to marine corrosion. Bars, Flats, Sheet Metal, Beams, Pipes LCNA (C<0.3%) MCNA 0.3≤C<0.5% Steels LCMA C<0.3% 5%≤∑AE<10% MCLA and MCMA LCHA (Stainless) LCHA (Hadfield) Structures. Thermal Resistance and Thermal stability (Cr, Mo) Pipes Pipelines Low temperature Applications Pipes, plates Pipelines Special equipment. Similar to MCNA but more hardness after heat treatment. Bars Tools Elements of machines Rust Free Luxury Antibacterial Pipes, Flats, Sheet metal Food containers Chemical industry equipment. Medical equipment Casting Tracks and rolls of caterpillars and similar equipment. Railroad. Elements that get harder with working impacts
  • 25. Influence of the carbon content in the Mechanical Properties of the steel. Elongation (%) 30 Strength (MPa) 1000 TS 500 15 YS 0 0 0.5 1 %C
  • 26. Influence of the Alloy Elements in Hardness and Impact) in Steels.
  • 27. Examples of classification of steels: 1. An steel with the following chemical composition: C=0.15%; P<0.002%, S<0.001% Will be classified as Low Carbon Non Alloy (LCNA) Steel . Notes: • Sulphur (S) and Phosphor (P) always are impurities in steels (They are not Alloy Elements). • Since C 0.15%, such steel is also called Mild Steel. • Low Carbon Steels have GOOD WELDABILITY and MALEABILITY.
  • 28. Example 2: 2. An steel with composition: the following chemical C=0.15%; Mn=1%, Si=2.0% P<0.002%, S<0.001% It Will be classified as: Low Carbon and Low Alloy (LCLA) Steel with 3.0 % of Alloy Elements. LCLA Steels Weldability. usually have GOOD or ACEPTABLE
  • 29. Example 3: 3. An steel with composition: the following chemical C=0.035%; Cr=18% and Ni=8% Will be classified as: Extra Low Carbon High Alloy (LCHA) Steel with (18 + 8)=26% of Alloy Elements. This is a typical Stainless Steel.
  • 30. Identification of American Steels According to the American Iron and Steel Institute (AISI) and the Society of Automotive Engineering (SAE) Steels are identified as follows: • A Four Digits code for Non Alloy, Low Alloy and Medium Alloy Steels. In this case the last two digits represents the carbon content in percentage while the first two digits the subgroup of steels according the alloy system and application. • A three digit code for High Alloy Steels (AISI) or five digits (SAE) where the last two of the five represents the carbon content. Notes: 1. In the following tables XX represents the carbon content in percentage. 2. American steels are used worldwide. 3. Some countries like Japan use same nomenclature. 4. The most of European countries follow a totally different nomenclature for example (Germany, Italy, Russia, France and England).
  • 31. Identification of NA, LA and MA Steels. 10XX Plain carbon, Mn 1.00% max 11XX Resulfurized free machining 12XX Resulfurized - Rephosphorized free machining 15XX Plain carbon, Mn 1.00-1.65% 13XX Mn 1.75% 23XX Ni 3.50% 25XX Ni 5.00% 31XX Ni 1.25%, Cr .65-.80% 32XX Ni 1.75%, Cr 1.07% 33XX Ni 3.50%, Cr 1.50-1.57% 34XX Ni 3.00%, Cr .77% 40XX Mo .20-.25% 44XX Mo .40-.52% 41XX Cr .50-.95%, Mo .12-.30% Nickel-ChromiumMolybdenum Steels 43XX Ni 1.82%, Cr .50-.80%, Mo .25% 47XX Ni 1.05%, Cr .45%, Mo .20-.35% Nickel-Molybdenum Steels 46XX Ni .85-1.82%, Mo .20-.25% 48XX Ni 3.50%, Mo .25% Carbon Steels Manganese Steel Nickel Steels Nickel-Chromium Steels Molybdenum Steels Chromium-Molybdenum Steels
  • 32. 50XX Cr .27-.65% 51XX Cr .80-1.05% 50XXX Cr .50%, C 1.00% min 51XXX Cr 1.02%, C 1.00% min 52XXX Cr 1.45%, C 1.00% min Chromiumvanadium steels 61XX Cr .60-.95%, V .10-.15% Tungstenchromium steels 72XX W 1.75%, Cr .75% 81XX Ni .30%, Cr .40%, Mo .12% 86XX Ni .55%, Cr .50%, Mo .20% 87XX Ni .55%, Cr .50%, Mo .25% 88XX Ni .55%, Cr .50%, Mo .35% 92XX Si 1.40-2.00%, Mn .65-.85%, Cr 0-.65% 93XX Ni 3.25%, Cr 1.20%, Mo .12% 94XX Ni .45%, Cr .40%, Mo .12% 97XX Ni .55%, Cr .20%, Mo .20% 98XX Ni 1.00%, Cr .80%, Mo .25% Chromium steels Nickelchromiummolybdenum steels Siliconmanganese steels Nickelchromiummolybdenum steels
  • 33. Identification of High Alloy Steels. Stainless Steels SAE AISI Chromium–Manganese–Nickel Steels 302xx 2YY Chromium–Nickel Steels 303xx 3YY Chromium Steels 514xx 4YY Chromium Steels 515xx 5YY In the most of the European countries to identify high alloy steels the chemical element is specified and after the amount except when is 1% for example: • 08Cr18Ni10T is a steel containing: 0.08%C, 18%Cr, 10%Ni and 1%Ti • 06Cr12Ni25 is a steel containing: 0.06%C, 12%Cr, 25%Ni
  • 34. Classification and application of Cast Irons. Cast Iron (C 1.7%) Non alloyed Malleable Gray • • • Ferritic Whiteheart Blackheart Perlitics Ferritic Perlitics Vermicular or Compact Alloyed Spheroidal graphite (SG). • • Perlitic Note: Cast Iron is obtain out of Casting process (in a mold) and it is use for parts that have to withstand vibrations and compression loads. White Ordinary ADI Corrosion High Temperature (Gray) Ni Si Abrasive Wear with Impact Antifriction (Whites) (Gray) Cr Cr-Ni Cr-Mo Ni Si (Gray) • • • Ni Si Al Whites •Cr • • •
  • 35. Applications of Copper Alloys. Copper Alloys. Brasses (Cu+Zn) • Yellow (Cu-Zn) • Leaded (Cu-Zn-Pb) • Tin (Cu-Zn-Sn-Pb) Bronzes (Cu+Sn). • Phosphor (Cu-Sn-P) • Lead Phosphor (Cu-Sn-Pb-P) • Aluminum (Cu-Al-Ni-Fe-Si-Sn) • Silicon (Cu-Si-Sn) Note: Cooper alloys, are mainly used in pipes, tubes, valves, fittings, antennas and in some cases friction bearings.
  • 36. Identification of Copper Alloys. Classification of copper alloys is determined by the Unified Numbering System (UNS),developed by the American Society for Testing and Materials (ASTM), Society of Automotive Engineers (SAE) and the Copper Development Association (CDA). The designation system uses five-digit numbers preceded by the prefix letter C. The numbers from C10000 through C79999 define the wrought copper alloys. Generic name Major components UNS designation number Copper (Technically Pure) >= 99.3% Cu C10100…C15999 High-copper alloys > 96% Cu but <99.3% Cu C16000…C19999 Yellow Brasses Cu-Zn C21000…C28999 Leaded Brasses Cu-Zn-Pb C30000…C39999 Tin Brasses Cu-Zn-Sn-Pb C40000…C49999 Phosphor Bronzes Cu-Sn-P C50000…C52999 Lead Phosphor Bronzes Cu-Sn-Pb-P C53000…C54999 Copper-Phosphorous alloys Cu-P, Cu-P-Ag C55000…C55299 Copper-Silver-Zinc Alloys Cu-Ag-Zn C55300…C60799 Aluminum Bronzes Cu-Al-Ni-Fe-Si-Sn C60800…C64699 Brasses Bronzes Silicon Bronzes and Silicon Brasses Cu-Si-Sn C64700…C66199 Other copper-zinc alloys Cu-Zn-… C66200…C69999 Copper-Nickels (Copper-Nickel-Iron Alloys) Spinodal Bronzes Cu-Ni-Fe Cu-Ni-Sn C70000…C73499 Nickel Silvers Cu-Ni-Zn C73500…C79999
  • 37. The numbers from C80000 through C99999 define the cast copper alloys. Generic name Coppers High-Copper Alloys Brasses Red Brasses and Leaded Red Brasses Yellow Brasses Manganese Bronzes and Leaded Manganese Bronzes Major components UNS designation number >= 99.3% Cu > 96% Cu but <99.3% Cu Cu-Sn-Zn Cu-Sn-Zn-Pb Cu-Zn C80000…C81399 Cu-Zn-Mn-Fe-Pb C86000…C86999 C81400…C83299 C83300…C84999 C85000…C85999 Silicon Bronzes and Silicon Brasses Cu-Zn-Si Copper-Bismuth Copper-Bismuth-Selenium alloys Cu-Bi Cu-Bi-Se C88000…C89999 Tin Bronzes and Leaded Tin Bronzes Nickel-Tin Bronzes Bronzes C87000…C87999 Cu-Sn-Zn Cu-Sn-Zn-Pb Cu-Ni-Sn-Zn-Pb C90000…C94500 C94600…C94999 Aluminum Bronzes Copper-Nickels (Copper-Nickel-Iron Alloys) Spinodal Bronzes Nickel Silvers Cu-Al-Ni-Fe Cu-Ni-Fe Cu-Ni-Sn Cu-Ni-Zn-Pb-Sn C95000…C95999 Copper-Lead Alloys Cu-Pb C98000…C98999 Special alloys Cu-… C99000…C99999 C96000…C96999 C97000…C97999
  • 38. Conclusions. • In industry Pure metals has not use, due the low properties. Alloys offer better properties due the inclusion of foreign atoms in the crystalline structure. • The chemical composition have influence in the Mechanical, Technological and Physical properties. • The most common alloys in our environment will be (Steels, Brasses, Bronzes and Cast Iron).
  • 39. Internet References • • • • • • Crystalline Structure. NTD Resource Center Wikipedia Encyclopedia How Stuffworks AISI / SAE Steel Identification Number Stainless Steels International Standards.