Aircraft Materials and Corrosion Training Manual PDF

Fundamentals M6 MATERIALS AND HARDWARE Rev.-ID: 1FEB2014 Author: WaJ For Training Purposes Only LTT Release: Mar. 27, 2015 EASA Part-66 CAT B1 M06_B1 E Training Manual...

Fundamentals M6 MATERIALS AND HARDWARE Rev.-ID: 1FEB2014 Author: WaJ For Training Purposes Only LTT Release: Mar. 27, 2015 EASA Part-66 CAT B1 M06_B1 E Training Manual For training purposes and internal use only.  Copyright by Lufthansa Technical Training (LTT). LTT is the owner of all rights to training documents and training software. Any use outside the training measures, especially reproduction and/or copying of training documents and software − also extracts there of − in any format at all (photocopying, using electronic systems or with the aid of other methods) is prohibited. Passing on training material and training software to third parties for the purpose of reproduction and/or copying is prohibited without the express written consent of LTT. Copyright endorsements, trademarks or brands may not be removed. A tape or video recording of training courses or similar services is only permissible with the written consent of LTT. In other respects, legal requirements, especially under copyright and criminal law, apply. Lufthansa Technical Training Dept HAM US Lufthansa Base Hamburg Weg beim Jäger 193 22335 Hamburg Germany Tel: +49 (0)40 5070 2520 Fax: +49 (0)40 5070 4746 E-Mail: [email protected] www.Lufthansa-Technical-Training.com Revision Identification:  The date given in the column ”Revision” on the face of  Dates and author’s ID, which may be given at the base  The LTT production process ensures that the Training this cover is binding for the complete Training Manual. of the individual pages, are for information about the Manual contains a complete set of all necessary pages latest revision of that page(s) only. in the latest finalized revision. Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 M6 MATERIALS AND HARDWARE FOR TRAINING PURPOSES ONLY! HAM US/O-6 WaJ May 15, 2013 ATA DOC Page 1 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General AIRCRAFT MATERIALS - GENERAL Materials Overview Metallic Materials Having the nature of metal or containing metal. Non-Metallic Materials Containing no metal. Ferrous Materials Iron, or any alloy containing iron. Non-Ferrous Materials A metal which contains no iron. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 02, 2011 01|Overview|L2|A/B1/B2 Page 2 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General FOR TRAINING PURPOSES ONLY! Figure 1 Metallic and Non-Metallic Materials HAM US/F-5 KhA Sep 02, 2011 01|Overview|L2|A/B1/B2 Page 3 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General General Abbreviations Conversions AA Aluminium Association of America Fahrenheit to Celsius Conversion AISI American Institute of Steel and Iron  °C = (°F - 32) x 0,555 AL Aluminium Celcius to Fahreinheit Conversion ALF3 Aluminium Fluorid  °F = °C x 1,8 + 32 Al2O3 Aluminium Oxide ALCOA Aluminium Corporation of America CAF2 Fluorspar Clad Cladding CO2 Carbon Dioxide Cr Chromium CRES Corrosion Resistant Steel Cu Copper DC Direct Chill F As fabricated H Strain hardened HO Water NA3ALF6 Cryolite Ni Nickel Mg Magnesium Mn Manganese FOR TRAINING PURPOSES ONLY! Mo Molybdenum O Annealed PSI Pounds per Square Inch SAE Society of Automotive Engineers Si Silicon T Heat treated Va Vanadium Zn Zinc HAM US/F-5 KhA Sep 02, 2011 02|General|L2|A/B1/B2 Page 4 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General THIS PAGE INTENTIONALLY LEFT BLANK FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 02, 2011 02|General|L2|A/B1/B2 Page 5 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Definitions Unit Stress If a load (force) is uniformly distributed over a certain area, the force per unit of area, usually expressed in pounds per square inch, is called the unit stress or simply the stress.  If the stress is the result of forces tending to stretch or lengthen the material it is called a tensile stress.  If it compresses or shortens the material a compressive stress.  if it sheares the material, a shearing stress.  If it twists the material, a torsion stress Tensile and compressive stresses always act at right angles to (normal to) the area being considered; shearing stresses are always in the plane of the area (at right angles to compressive or tensile stresses). FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 02, 2011 03|Definitions|L2|A/B1/B2 Page 6 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General TENSION COMPRESSION FOR TRAINING PURPOSES ONLY! SHEAR Figure 2 Stresses HAM US/F-5 KhA Sep 02, 2011 03|Definitions|L2|A/B1/B2 Page 7 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General DEFINITIONS (CONTD.) Strength of Materials Poisson’s Ratio Strength of materials deals with The ratio of lateral strain to longitudinal unit strain for a given material  the relations between external forces applied to an elastic body and the subjected to uniform longitudinal stress within the proportional limit. deformations and internal stresses resulting from those applied forces.  For steel, it equals 0.30.  the use of the principles of strength of materials to meet functional  For wrought iron, 0.28. requirements.  For cast iron, 0.27. Certain formulas that are used in strength of materials calculations are based  For brass, 0.34. solely on mathematical analyses; others (empirical formulae) are the result of experiment, test and observation. Whether of the former or the latter type, Yield Strength most of these formulae make use of certain concepts and experimentally The maximum stress that can be applied to a material without permanent determined physical properties of materials such as tensile strength, modulus deformation of the material. of elasticity etc. The meaning of some of these terms is explained in the following paragraphs. Ultimate Strength The stress at which a material in tension, compression or shear will fracture. Elasticity A body is said to be perfectly elastic if, after it has been deformed by external Modules of Elasticity forces, it returns completely to its original shape when the forces are removed. Modulus of Elasticity: The ratio of stress to strain within the proportional limit of Although there are no perfectly elastic materials, steel and some other a material in tension or compression. structural materials may be so considered in certain ranges of loading and deformation (see elastic limit). Partially elastic materials are those that do not completely resume their original shape when the external forces are released, some of the energy of deformation having been lost in the form of heat. Teilweise elastische Materialien sind solche, die ihre Ursprungsform nicht mehr vollständig erreichen, wen die Kraft nicht mehr wirkt. Dies geschieht, weil Teile der Verformungsenergie in Form von Wärme verloren gegangen sind. Combined Stress FOR TRAINING PURPOSES ONLY! When the stress on a given area is a combination of tensile and shearing stresses, or, compressive and shearing stresses, the resulting stress on the area is called a combined stress. Simple Stress When a tensile, compressive or shearing stress alone is considered to act, a body is said to be subject to a simple stress. HAM US/F-5 KhA Sep 02, 2011 03|Definitions|L2|A/B1/B2 Page 8 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Properties of Material Hardness Enables a material to resist penetration, wear or cutting action. Strength Ability of a material to withstand forces which tend to deform the metal in any direction, or the ability of a material to resist stress without breaking. Elasticity The ability of an object or material to be stretched and recover its size and shape after deformation. Plasticity The property of a metal which allows it to be reshaped. Ductility The property which allows metal to be drawn into thinner sections without breaking. Malleability That characteristic of material that allows it to be stretched or shaped by beating with the hammer or passing through rollers without breaking. Toughness The property of a metal which allows it to be deformed without breaking. Brittleness The property of a metal to break when deformed or hammered. It is the FOR TRAINING PURPOSES ONLY! resistance to change in the relative position of the molecules within the material. Conductivity The characteristic of a material which makes it possible for it to transmit heat or electrical conduction. Durability The property of metal that enables it to withstand force over a period of time. HAM US/F-5 KhA Sep 02, 2011 03|Definitions|L2|A/B1/B2 Page 9 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Metal General General Metals consist of basic chemical elements which have different characteristics For airframe constructions, mainly lightweight metals are used, ie metals with a and properties: density less than 5 Kg/ dm3.  strength, heat-treatable or cold-workable The three most important lightweight metals in aircraft structure are:  crystal structure  Aluminium and Aluminium alloys (density 2,7 Kg/dm3)  heat and electrical conductivity  Titanium and Titanium alloys (density 4,5 Kg/dm3)  light impenetrability  Magnesium and Magnesium alloys (density 1,74 Kg/dm3)  metallic gloss by light-reflection On aircraft structures where high weights or higher strengths are needed,  dissolvability in acids under formation of salts. heavyweight metals and their alloys are applicable (density between 7,85 Kg/dm3 and 9,5 Kg/dm3). There are about 70 metals (chemical elements) which are used in different applications in technical fields combined in several variants of alloys and unalloyed conditions. 5 kg/dm3 Mg − Magnesium FOR TRAINING PURPOSES ONLY! Mg Al Ti Zn Fe Cu Al − Alumin Aluminum Ti − Tit Titanium 1.74 2.7 4.5 7.14 7.86 8.93 Zn − Zi Zink Fe − Iron Lightweight Metals Heavyweight Metals Cu − Copper HAM US/F-5 KhA Mar. 23. 2015 04|Metals|L2|A/B1/B2 Page 10 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Metals of Aircraft Structure Material Elements Density kg/dm3 Melting Point Intended use Magnesium Mg 1.74 650C are seldom used, mainly as al- loy with Al,Zn,Mn Silicon Si 2.33 1420C as alloy ingredient only Aluminum Al 2.70 658C most commonly used Material- as pure aluminum and alumi- num alloy Titanium Ti 4.50 1727C as pure titanium or titanium al- loy Zinc Zn 7.14 419C as alloy ingredient only Manganese Mn 7.30 1250C as alloy ingredient only Iron Fe 7.86 1539C not in pure Form, Steel with C and alloy ingredient Copper Cu 8.93 1083C for electrical wire and alloy in- gredient FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Mar. 23. 2015 04|Metals|L2|A/B1/B2 Page 11 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Crystal and Cells General Structural metals in solid state form as crystals. A crystal is a rigid body in which the constituent particles are arranged in a repeating pattern. The basic building block of the crystal is known as a unit cell. The crystal is built from the repetition of these identical unit cells. The most common unit cells are: Body-Centered-Cubic (BCC) The body centred cubic (BCC) has a total of nine atoms. One is at each corner of the cube and one in the centre. Face-Centered-Cubic (FCC) The face centred cubic (FCC) unit cells consists of 14 atoms. One atom is at each cube corner and one is in the centre of each face. Aluminium, copper, gold, nickel, silver and iron are examples of metals that have the FCC form. These are ductile metals. Hexagonal Closed Packed (HCP) Cobalt, magnesium, titanium and zinc have the hexagonal close packed (HCP) arrangement. There are 17 atoms in HCP unit cells, one in every corner and one in the middle of the two faces. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA MAR. 23.2015 05|Crystal Cells|L2|A/B1/B2 Page 12 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Cube Body-Centered-Cubic Face-Centered-Cubic FOR TRAINING PURPOSES ONLY! Hexagonal Closed Packed Figure 3 Crystals and Cells HAM US/F-5 KhA MAR. 23.2015 05|Crystal Cells|L2|A/B1/B2 Page 13 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Material Development GENERAL The selection of materials should be the best compromise between the quality of the material to fulfil the requested function and all costs (material prices, processing time and effort, maintain and repair of structure, etc) at the time of the aircraft development. A change of material in existing programmes is difficult and expensive (a new airworthiness certification is necessary, changes in all programme documentation drawings). Nevertheless, airframe manufacturers spend time and effort finding new solutions to raise the quality of the aircraft or to reduce manufacturing costs. Material specialists do this, for all existing programmes and for new developments in their specific field. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 02, 2011 06|Mat Develop|L2|A/B1/B2 Page 14 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - GENERAL Aircraft Materials General Boeing Airbus Comp. 14% 2000 Steel 8% Steel Titan. 3% 15% Comp. 4% Titan. 6% Various 3% Aluminum 78% Aluminum 69% Steel 6% 2010 Titan. 9% Aluminum Steel Titan. 3% Various 4% 20% 15% Aluminum 35% FOR TRAINING PURPOSES ONLY! Composites Composites 46% 62% Figure 4 Material Development HAM US/F-5 KhA Sep 02, 2011 06|Mat Develop|L2|A/B1/B2 Page 15 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 M6.1 AIRCRAFT MATERIALS - FERROUS CHARACTERISTICS, PROPERTIES & IDENTIFICATION OF COMMON ALLOY STEELS General Introduction The base material iron is the chemical element Fe which, in its pure form, is a very soft, malleable and ductile metal which is easy to form and shape. Steels In practical use pure iron is very seldom encountered, but it is mixed with various other alloying agents. Steel is an excellent engineering material with many applications. For aircraft use, however, it does have some significant problems. The main restrictions are its high density of > 7,85 Kg/dm3 (approximately 3 times the density of aluminium) and its susceptibility to corrosion. The resistance of steel against corrosion can be increased by the addition of large quantities of certain alloying elements, but this can have significant effects on properties and costs. Steel application in aircraft structures Between 8 and 16% (Airbus A320: 9%, Boeing B777: 11%) of an aircraft’s structure is alloy steel including stainless steels. The high strength and high modulus of elasticity are the primary advantages of the high-strength steels. This is useful for designs with space limitations e.g. landing gear components or flap tracks. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 01|M6.1a|L2|A/B1/B2 Page 16 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 BOEING AIRBUS 1990 Steel Steel 8% 16% Titan 6% Titan 3% Composites 4% Miscellaneous 3% Composites 14% Aluminium 77% Aluminium 69% Steel Steel 6% 15% >2010 Titan 9% Aluminium Miscellaneous 4% Titan 3% Aluminium FOR TRAINING PURPOSES ONLY! 20% 35% Composites Composites 62% 46% Figure 5 Prognosticated Material Proportions on Aircraft HAM US/F-5 KhA Sep 01, 2011 01|M6.1a|L2|A/B1/B2 Page 17 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Steel Grades General Steel grades are the different kinds of steels and are distinguished by the specific properties, which are assured by the manufacturer. The specific properties of the steels are given by different chemical composions (alloys) and specific heat treatments. NON ALLOYED STEELS Non alloyed steels can be distiguished into construction steels and carbon steels, but is has to be mentioned that they can also be differenced otherwise. Construction steel Carbon content 0,05 up to 0,5 %. The weldability of this steel is good, but it’s hardening is unspecific and the stiffness and ultimate strength is at a low level. This steel is not used on aircraft due to it’s relatively low ultimate strength value. Carbon steel Carbon content 0,5 up to 0,8% This steel can be hardened, is suitable for annealing and surface hardening. Due to the very low content of alloying elements of the non alloyed steels, the mechanical properies are sufficient for applications like:  springs,  tools,  wires and welding wires. FOR TRAINING PURPOSES ONLY! This steel is used for aforementioned applications on aircraft. HAM US/F-5 KhA Sep 01, 2011 02|M6.1a|L2|A/B1/B2 Page 18 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Strength of Non Alloyed Steels Steel grade acc. to EN 10027 Tensile strength (Rm) in N/mm2 Yield strength (Re) in N/mm2 Carbon content (C) in % (DIN17100) S205 (former St 34) 340 bis 420 200 bis 210 0.17 S235 (former St 37) 370 bis 450 220 bis 240 0.20 S260 (former St 42) 420 bis 500 240 bis 260 0.25 E335 (former St 60) 600 bis 720 320 bis 340 0.40 Tool steel depending on treatment 0.3 bis 1.6 Steels for quenching and tempering depending on treatment 0.2 bis 0.6 Designations of Non Alloyed Steels According to the EN 10027−Standard, letter „S“ is used for „Structural Steel“ (former: construction steel). Letter „E“ is used for „mechanical engineering steels“ or the german word „Einsatzstahl“, which means „case hardening steel“. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 02|M6.1a|L2|A/B1/B2 Page 19 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Alloying Ingredients General alloying elements The main alloying agents of steel are:  Carbon (not considered as an alloying element) Increases strength and hardness. Reduces toughness, formability and weldability.  Sulphur increases the brittleness.  Manganese produces a clean, tough and uniform metal.  Silicon acts as a hardener.  Phosphorous raises the yield strength and corrosion resistance.  Nickel adds strength and hardness. Nickel is the major ingredient for corrosion resistant steel.  Chromium increases the strength, wear and corrosion resistance.  Molybdenum increases impact strength and elastic limit.  Vanadium increases the tensile strength and toughness. FOR TRAINING PURPOSES ONLY!  Titanium reduces the brittleness of the steel. HAM US/O-6 WaJ Feb 11, 2014 03|M6.1a|L2|B1 Page 20 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 FOR TRAINING PURPOSES ONLY! Figure 6 Alloying Elements HAM US/O-6 WaJ Feb 11, 2014 03|M6.1a|L2|B1 Page 21 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Alloy Steel on Aircraft Structures General High alloy steels The high density of steels reduces the amount on aircraft structure down to 8 Where corrosion resistance, anti chafing properties, wear resistance and heat up to 16%, depending on aircraft-model and aircraft manufacturer. resistance is required, stainless steels respectively high alloy steels are used in The high strength and high modulus of elasticity are the primary advantages of those areas (actuators, fittings, door sills, pylon-areas, anti-chafing plates in the high-strength steels. This is useful for designs with space limitations. fuselage-, empenage- and flap-areas, also wash basins, etc.). The abbreviation CRES means: Material requirements CRES The selection of specific materials in these areas depends on requirements like: Corrosion  strength and hardness, REsistant  stiffness and fatigue properties, Steel  corrosion resistance and service temperature. Grades of steels on aircraft Alloy steels on aircraft are broken down into two groups: low alloy- and high alloy steels. Low alloy steels For example gears, flap-ballscrews and flap-tracks are manufactured from high strenth alloy steels to sustain high service loads. For these applications, low alloy quenching and tempering steels are used, which are named „HHT“. H H T High strength steel FOR TRAINING PURPOSES ONLY! Heat Treated HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 22 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 HHT: High Strength Heat Treated Steel CRES: Corrosion Resistant Steel INBOARD FLAP TRACKS HHT FLAP LINKAGE LANDING GEAR CRES AND HHT HHT REAR ENGINE MOUNT High Alloy Steel SLAT TRACKS HHT FOR TRAINING PURPOSES ONLY! HYDRAULIC LINES CRES ENGINE MIDSPAR ATTACH FITTINGS HHT FRONT ENGINE MOUNT, STRUT LOWER SPARS, WEBs AND CHORDS: CRES Figure 7 General Applications for Steel (A320) HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 23 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 High Strength Heat treated Steels Material consistence Low alloy steels normally contain less than 5% of alloying elements/matals and between 0.25 and 0.8% carbon. Low alloy steels seldom may contain up to a total of 8% of alloying elements and between 0.25 and 0.8% carbon. In this case, the total of alloying elements exceeds the 5%-limit, but no single element by itself exceeds this limit. Main properties Most of the low alloy steels defy a non-cutting shaping process, like bending, beating, stretching or compressing. But cold short may appear, if low alloy steels are shaped in a non-cutting process (without any heat treatment). Due to the tendency of low plastically elongation of these steels, stress cracking occurs in tensile load areas cause the fact, that yield strength and fracture are at very close quarters. Designation of low alloy steels Low alloy quenching and tempering steels are denominated as HHT (High Strength Heat Treated). FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 24 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 FOR TRAINING PURPOSES ONLY! Figure 8 HHT-Application General HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 25 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Material designations of HHT-Steels Common Aviation Standards For aviation application, steels can be identified by the American AISI−Standard or the German Luftfahrtnorm. Due to the fact, that the german Luftfahrtnorm is rarely used, it won’t be elaborated on. AISI-STANDARD: AISI 4130 American Institute for Steel and Iron The system refers to the chemical composition of the alloy. The meaning of the the digits is: First digit:  4 refers to the specific primary alloying element: − 1 only carbon or manganese − 2 Nickel − 3 Nickel-chromium − 4 Molybdenum alloy steel (Cr-Mo, Ni-Mo or Ni-Cr-Mo) − 5 Chromium − 6 Chromium-vanadium − 7 Tungsten-chromium − 8 Nickel-chromium-molybdenum FOR TRAINING PURPOSES ONLY! − 9 Silicon-manganese or Ni-Cr-Mo Second digit:  1 refers to the subrounded percentage of the primary alloying element. Due to the limited capability of this simple encoding, a precise recoding of any alloy is not given! Third and fourth digit:  30 refers to content of carbon in 1/100 %. HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 26 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 FOR TRAINING PURPOSES ONLY! Figure 9 Material Designations HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 27 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Examples of HHT-Application on Aircrafts Primary HHT-Steel alloys Most widely used HHT-Steels on modern aircraft are the alloys:  4130 − is the common steel alloy for use in the 180-200 ksi range  4340 − has a strength range of 200 ksi up to 280 ksi and is commonly used in the 260-280 ksi range.  300M − an even higher strength alloy is 300M, most commonly used for aircraft landing gear components. It can be hardened to the 240-290 ksi range. STRENGTH RANGE (K S I) ALLOY 125 - 145 150 - 170 160 - 180 180 - 200 220 MIN 275 - 300 4340 X X X X 4330M X X X 9Ni-4Co-.30C X 4340M X FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 28 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 RETRACTION LINK RETRACTION LEVER Main Landing Gear A340 FORWARD PINTLE−PIN FITTING GEAR SUPPORT RIB 6 CARDAN PIN WING REAR SPAR 300M alloy is equivalent to AMS 6417 or 6419 SHORTENING LINKAGE FITTING 6417 − 1,8%Ni, 1,6%Si, 0,82%Cr, 0,4%Mo, 0,08%V (0,38 − 0,43%C) 6419 − same as 6417, but carbon contend slightly changed (0,4−0,45%) REAR PINTLE−PIN FITTING 4330 − 1,8%Ni, 0,88%Cr, 0,42%Mo, 0,08%V (0,28 − 0,33%C) 4330U − same as 4330, but with specific material test SHORTENING MECHANISM 4340 − 1,8%Ni, 0,80%Cr, 0,25%Mo (0,38 − 0,43%C) RETRACTION ACTUATOR 4330U DOWNLOCK ACTUATOR SIDE STAY FITTING Ti 6Al V4 LOCKING ARM SIDE STAY ASSEMBLY 7049−T73 300M MLG LEG DOWNLOCKING JACK 300M S99/4340 PITCH TRIMMER ARTICULATING LINKS 4330U SLIDING TUBE TORQUE LINKS 300M 300M FOR TRAINING PURPOSES ONLY! BOOGIE BEAM ASSY 300M BRAKE ROD Figure 10 HHT-Application Main Gear HAM US/F-5 KhA Sep 01, 2011 04|M6.1a|L2|A/B1/B2 Page 29 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 M6.1A AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Properties of HHT-material REWORK PRECAUTIONS FOR HHT STEEL-HANDLING General When doing rework operations on HHT-Steel parts, some precautions must be observed, to avoid negativ influence to the specific material-properties. Following HHT-material sensitivities are identified as a significant item:  Notch sensitivity  Cold-shortness sensitivity  Temperature sensitivity  Hydrogen embrittlement Notch Sensitivity Since most steel parts are highly-stressed, localized stress concentrations are undesirable, must be avoided/respectively should always be removed. Small surface damage such as scratches, nicks or corrosion causes a change of stress distribution of the component, risk of cracking would be the result. Cold-Shortness Sensitivity Socalled „cold-shortness“ occurs when low-alloyed steels are deformed chipless in the cold state. Due to light strain, that is low plastic moldability, cracks similar to stress cracks occur at the strained areas. The reason for this is that practically no plastic strain occurs, which means that the yield strength and the crack lie very closely together. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 05|M6.1a|L2|A/B1/B2 Page 30 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 M6.1A AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Temperature Sensitivity With components made of hardened steel, an accidental application of heat, such as mechanical processing/overheating during flight, can lead to structural changes of the material and loss of stability. On principle, the different maximum permissible working temperatures of the different alloys may not be exceeded. NOTE: Mechanical processing of HHT-components should only be carried out with hand tools or slowly running hand-held machines. Hydrogen Embrittlement Any wetting with acidic fluids or mordants can lead to hydrogen embrittlement of the surface of HHT-components. Critical are, for example, phosphate-ester-acids (hydraulic fluids such as „Hyjet“), vinegar sealant (RTV 159), and paint systems such as wash-primers. This will result in stress cracks, which often spread through the entire component and lead to its failure, due to an unfavorable crack propagation resistance. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 05|M6.1a|L2|A/B1/B2 Page 31 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 PROPERTIES OF HHT-MATERIAL General The following properties of HHT-steels have been identified as significally problematic in the past, with regard to the sensitivity:  Notch sensitivity  Cold-shortness sensitivity  Hydrogen embrittlement  Temperature sensitivity at temperatures above about 250C (depending on the material) NOTCH SENSITIVITY General HHT-steels are subjected to special thermal treatment due to mechanical requirements (hardness, strength, strain, toughness). In the process, a task- specific optimum of hardness and strength should be achieved. Due to a reatively high original strength of a minimum of 180 KSI/1240N/mm2 and concurrent surface hardening, these components are especially prone to notch sensitivity. CAUTION: MINOR DAMAGES, SUCH AS STRIAE, NOTCHES OR RUST ON THE SURFACE LEAD TO A CHANGE OF STRESS DISTRIBUTION IN THE COMPONENT, WHICH RESULTS IN A RISK OF CRACKING. When the load spectrum changes continuously or suddenly, this inevitably leads to socalled fatigue fracture. Impact loading, e.g. on the landing gear, are caused by: FOR TRAINING PURPOSES ONLY!  Landing shock, which means high static loads. continuous loads are caused by:  Rolling motion on the ground, which means dynamic loads due to alternating loads. These problems increase, the more hardness and strength of the material increase. HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 32 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 F F F σ= A 1 σ 2 > σ 1 A A FOR TRAINING PURPOSES ONLY! F F Figure 11 Notch Sensitivity HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 33 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 COLD-SHORTNESS SENSITIVITY General Almost all low-alloyed steels resist chipless deformation in the cold state, such as bending, forcing, stretching and compressing. Socalled „cold-shortness“ occurs when low-alloyed steels are deformed chipless in the cold state. Due to light strain, that is low plastic moldability, cracks similar to stress cracks occur at the strained areas. The reason for this is that practically no plastic strain exists in these materials, which means that the yield strength and the crack lie very closely together. In most cases, embrittlement occurs in the deformed area, in connection with cold-shortness. FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 34 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 FOR TRAINING PURPOSES ONLY! Figure 12 Cold-Shortness Sensitivity HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 35 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 HYDROGEN EMBRITTLEMENT POTENTIAL General Hydrogen embrittlement is a phenomenon that occurs in various metal systems, particularly ferrous and titanium alloys, under sustained loads at stresses far below the actual ultimate tensile strength. CAUTION: FRACTURE OF THE PART CAN OCCUR UNDER LOADS AS LOW AS 30% OF THE YIELD STRENGTH AFTER ONLY A FEW THOUSAND SERVICE HOURS. The susceptibility of steel parts to hydrogen embrittlement increases as the hardness and strength increase. Steel parts heat-treated to 200 KSI and above are highly susceptible whereas parts heat-treated to 180-200 KSI are only susceptible if they are subjected to high sustained stresses. Aluminium, 300 series stainless steels and precipitation hardenable steels (15-5 PH etc) are not affected. Procedure of hydrogen embrittlement In ferrous alloys, hydrogen embrittlement occurs when an alloy steel or a 400− series stainless component containing small amounts of hydrogen is subjected to a sustained load. The hydrogen can be introduced into the component during processing. Certain solvents and plating processes can introduce hydrogen into the surface of the part. The hydrogen will migrate to an area of triaxial stresses (such as occur at notches, corrosion pits or other stress raisers) once it is present in the metal surface. The resulting hydrogen concentration then causes the initiation and propagation of a brittle crack. FOR TRAINING PURPOSES ONLY! The stresses required for an embrittlement failure may be caused by improper processing or installation-induced residual stresses rather than service induced. Hydrogendesorption Since only a very thin surface layer will be affected, the hydrogen can easily be removed by a bake operation at 375F (190C) as long as the part is bare (unplated) or plated with a porous plating such as titanium-cadmium plating. HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 36 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 High susceptible to embrittlement Susceptible to embrittlement EMBRITTLEMENT SUSCEPTIBILITY 190 - 230 C for not less than 18 hours 190 - 230 C for not less than 4 hours FOR TRAINING PURPOSES ONLY! 1000 MPa 1400 MPa 140 KSI 200 KSI TENSILE STRENGTH Figure 13 Hydrogen Embrittlement HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 37 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 TEMPERATURE SENSITIVITY OF HHT-MATERIAL General HHT-steels are only hardenable because of carbon, which means that this type of steel can only be hardened due to the existence of a certain carbon content. At this, a special material structure is created by specific thermal treatment in order to achieve a specific optimum of hardness and strength. If however a HHT-component is subjected to incorrect mechanical processing, or accidental application of heat during flight, this can lead to structural changes of the material. This leads to softening zones or overcuring zones, depending on the temperatures acting on the respective alloy. CAUTION: BLUNT LATHE TOOLS, MILLING CUTTERS, DRILLS, TOO HIGH ROTARY SPEEDS, TOO HIGH FEED RATE/CONTACT PRESSURE, INSUFFICIENT COOLING AND SO ON LEAD TO FRICTION TEMPERATURES WHICH CAN CAUSE STRUCTURAL CHANGES OF THE MATERIAL! SURFACE TEMPERATURES HIGHER THAN ABOUT 250C HAVE TO BE AVOIDED AT ALL COSTS WITH STEELS WITH A STRENGTH OF 220 KSI (1540N/MM2) OR HIGHER! FOR TRAINING PURPOSES ONLY! HAM US/F-5 KhA Sep 01, 2011 06|M6.1a|L2|B1 Page 38 Lufthansa Technical Training MATERIALS AND HARDWARE EASA PART-66 M6 AIRCRAFT MATERIALS - FERROUS Characteristics, Prop. & Ident. of common alloy steels M6.1 Temperature ο E C G Austenite Austenite + Secondary Cementite Ferrite + Austenite S K Ferrite + Perlite Secondary Cementite + Perlite