Chapter 2 Material and Manufacturing Properties

1. Chapter 2Material and Manufacturing Properties Chapter 2: Material and Manufacturing Properties - IE252

2. Chapter 2 Chapter 2: Material and Manufacturing Properties. 2.1Material Properties2.2 Importance of material properties in manufacturing 2.2.1 Forming from liquid state. 2.2.2 Forming from solid state. 2.2.3 Joining processes2.3 Effect of manufacturing processes on material properties.2.4 Strength increase techniques in metals.2.4.1 Hardening by solid-state phase transformation.2.4.2 Strain hardening. 2.4.3 Dispersion hardening.2.5 Classification of materials 2.6 Ferrous metals. 2.6.1 Steel classification based on the amount of alloying element 2.6.2 Steel classification based on its applications. 2.7 Cast Iron. 2.8 Nonferrous metals ……. Chapter 2: Material and Manufacturing Properties - IE252

3. Chapter 2: Material and Manufacturing Properties. 2.1 Material Properties Material properties covers:* Physical properties, which include color, density, melting point, freezing point, specific heat, heat of fusion, thermal conductivity, thermal expansion, electrical conductivity, …etc.* Chemical properties, e.g. corrosion resistance.* Mechanical properties, e.g. reaction of material under mechanical loading.* Technological or manufacturing properties, which describe the suitability of a material for given manufacturing process. The technological properties are evaluated using different tests and special terms are used for these tests, e.g. “formability”, “hardenability”, “cast- ability”, “electric or/and thermal conductivity”, …etc. Detail description of these test may be found in literatures [2.1] Chapter 2: Material and Manufacturing Properties - IE252

4. Chapter 2: Material and Manufacturing Properties. • 2.2 Importance of material properties in manufacturing Assigning Material For A Product ?* The suitability of the material for the given application. For example, plastic materials can be used as electric or thermal insulation on some domestic utilities due to its electric and thermal insulation. Copper metals are usually used to manufacture coolers and heat exchangers of automotive industries due to high thermal conductivity and lightweight compare to other metals.* The suitability of the material for given manufacturing process, for example it is possible to select a cheap material for a given product, but it may be too expensive to produce this material by a given manufacturing process. * The economical consideration should also be considered, as final decision for assigning a material for a given product. Chapter 2: Material and Manufacturing Properties - IE252

5. Chapter 2: Material and Manufacturing Properties. • 2.2 Importance of material properties in manufacturing Material properties changed using manufacturing processes: (forming from solid state or liquid state)Forming from liquid state:Melting phase, Shaping phase, Solidification phase:In melting phase (there are single melting temp for pure metals and melting range for alloys (mixture of solid and liquid metals)) Chapter 2: Material and Manufacturing Properties - IE252

6. Chapter 2: Material and Manufacturing Properties. • 2.2 Importance of material properties in manufacturing Material properties changed using manufacturing processes: (forming from solid state or liquid state)Forming from liquid state:Melting phase, Shaping phase, Solidification phase:In melting phase (there are single melting temp for pure metals and melting range for alloys (mixture of solid and liquid metals))During solidification of alloys, there is a change in volume associated with the transition from liquid to solid states. This means, that the metal will be missing in the central of the component as solidification starts at the outside of the component. Compensation for this is established by placing risers (reservoirs of molten metal) on component during casting process. These riser/risers must be designed such that it solidifies last after component solidification. Furthermore, increasing the solidification range, results in improper chemical composition during melting metal, and will increases the risk of internal porosity, hot tearing, and segregations. Chapter 2: Material and Manufacturing Properties - IE252

7. Chapter 2: Material and Manufacturing Properties. • 2.2 Importance of material properties in manufacturing Melting phase, Shaping phase, Solidification phase:In melting phase (there are single melting temp for pure metals and melting range for alloys (mixture of solid and liquid metals))For example, cast iron has 2% contraction, while 3% for cast steel. Aluminum has contraction allowance between 3.5-8.5%. During solidification phase, solidification or grain growth start externally and end at the part center. This result in harder external surface and soft or ductile in part inner zone Chapter 2: Material and Manufacturing Properties - IE252

8. Chapter 2: Material and Manufacturing Properties. • 2.3 Effect of manufacturing processes on material properties. Forming from solid state:The effects of material properties on metal forming processes starting from solid state can be demonstrated clearly in mass-conserving processes, mass-reducing processes and/or joining processes.Mass-reducing process (metal cutting):Mass-conserving process (metal forming):Mechanical basic process is a primary basic process in most metal forming processes. The suitability of a metal to undergo plastic deformation without failure (material instability), is measured by the material ductility.The suitability of a material to undergoes plastic deformation without failure is obtainable from the stress-strain curves of the tensile tests. For example, the strain at instability, the percent of elongation, and reduction or area are most important factors obtainable from tensile stress-strain curve. Most material have a good correlation between the reduction of area (in tensile test specimen) and the “formability” of material in metal forming processes. Chapter 2: Material and Manufacturing Properties - IE252

9. Chapter 2: Material and Manufacturing Properties. • 2.3 Effect of manufacturing processes on material properties. Forming from solid state:The effects of material properties on metal forming processes starting from solid state can be demonstrated clearly in mass-conserving processes, mass-reducing processes and/or joining processes.Mass-reducing process (metal cutting):The primary basic processes in mass reducing processes are either mechanical, fracture (ductile or brittle type); or chemical, dissolution and combustion; or thermal, melting.Most industrial mass reducing processes based on mechanical fracture are metal cutting processes. The suitability of a material for machining processes called ‘Machinability’, which is variable for different materials. The parameters covers the Machinability are tool wear, surface finish, cutting forces and/or chip formation.Machinability is a function of mechanical properties, chemical composition, and heat treatment of processed material. For example, a material has a good Machinability, when it has low ductility, low strain hardening and low hardness (mechanical properties). Furthermore, adding small amount of lead, manganese, sulfur, selenium or tellurium to machined material will increase Machinability without changing the mechanical properties (changing chemical composition). Chapter 2: Material and Manufacturing Properties - IE252

10. Chapter 2: Material and Manufacturing Properties. • 2.3 Effect of manufacturing processes on material properties. Forming from solid state:The effects of material properties on metal forming processes starting from solid state can be demonstrated clearly in mass-conserving processes, mass-reducing processes and/or joining processes.Mass-reducing process (metal cutting):Joining process (metal forming):Joining processes are based either on thermal or thermal and mechanical or just mechanical basic processes. Fusion welding is based on thermal (melting) and mechanical (flow) basic processes. While, thermal (heating) and mechanical (plastic deformation) are basic processes for resistance welding, e.g. spot welding process. Adhesive bonding has mechanical (flow) basic process Chapter 2: Material and Manufacturing Properties - IE252

11. Chapter 2: Material and Manufacturing Properties. • 2.3 Effect of manufacturing processes on material properties. Forming from Liquid state: In forming from the liquid state material (mass conserving process), e.g. metal casting process, the final properties depends mainly on the composition (including solidification temperature range), the thermal and mechanical properties of the mold or die material, and solidification conditions (solidification rate, its direction ...etc).In forming from solid state by plastic deformation as a basic process (mass conserving process), the amount of deformation, the temperature, and rate of the deformation primary determine the final properties. For example, cold work deformation increases the material strength and decreases ductility. While, hot work deformation gives poor surface finish and reasonable mechanical properties. The metal cutting process, primarily influences the surface quality e.g. roughness, hardness, internal stresses ..etc. Chapter 2: Material and Manufacturing Properties - IE252

12. ,Strength/strain ,σu and σo ,Grain growth Ductility ,εb ,Strength/hardness ,Temperature increase ,Cold work % ,Fig. 2.3 Variation of ductility, strength/hardness, and grain growth with temperature increase. ,Fig. 2.2 Variation of yield stress(σo), ultimate stress(σu) and elongation percent (εb) with increase of cold work. Chapter 2: Material and Manufacturing Properties. • 2.4 Strength increase techniques in metals. Different industrial techniques are common to increase the strength of metals. These cover the following techniques: * Phase transformation in solid state; (a) Martensitic (diffusionless) transformations, and (b) Precipitation (diffusion type).* Strain hardening, (cold work and cold work see Fig 2.2, and 2.3)* Dispersion hardening, see section 2.4.3. Chapter 2: Material and Manufacturing Properties - IE252

13. Chapter 2: Material and Manufacturing Properties. • 2.4 Strength increase techniques in metals. In Strain hardening:In metal forming processes the deformation is carried out at room temperature or elevated temperatures. Cold working process refers to deformation carried out at temperatures below the recrystallization temperature, while in hot working the deformation is carried out at temperature above recrystallization temperature (sometime called forging temperature).In general, yield stress and ultimate stress increase with increasing the amount of cold work, while the percentage elongation decreases with the increase of the amount of cold work, see Fig. 2.2. Chapter 2: Material and Manufacturing Properties - IE252

14. Chapter 2: Material and Manufacturing Properties. • 2.4 Strength increase techniques in metals. In Strain hardening:In metal forming processes the deformation is carried out at room temperature or elevated temperatures. Cold working process refers to deformation carried out at temperatures below the recrystallization temperature, while in hot working the deformation is carried out at temperature above recrystallization temperature (sometime called forging temperature).In general, yield stress and ultimate stress increase with increasing the amount of cold work, while the percentage elongation decreases with the increase of the amount of cold work, see Fig. 2.2. Chapter 2: Material and Manufacturing Properties - IE252

15. Chapter 2: Material and Manufacturing Properties. • 2.4 Strength increase techniques in metals. In Strain hardening ……….. continue:After deformation the structure grains becomes elongated in certain direction and contracted in another direction, this called anisotropy. This means the metal has different properties in different directions. By heat treatment, it is possible to release the stresses or the deformation in the matrix grains and this procedure called recrystallization, these results in grain size growth, see Fig. 2.3. Recrystallization temperature is nearly half the melting point of metals Chapter 2: Material and Manufacturing Properties - IE252

16. Chapter 2: Material and Manufacturing Properties. • 2.5 Classification of materials • Manufacturing materials are divided into three main groups given as follows: • Metallic material group, • Nonmetallic material group, and • Composite material group. Here End Chapter 2 Chapter 2: Material and Manufacturing Properties - IE252