APPLIED MECHANICS LAB MATERIAL SCIENCE

Lab Title: 2 Title: Microstructure Study of Ferrous and Non Ferrous Alloys under Various Compositions and Heat Treatment Conditions.Objective: Upon completing this experiment, student should be able to;1. Understand the different between ferrous and non-ferrous alloys from the metallurgical point view.2. Understand the phase diagram of iron-carbon and alloys systems that enables for heat treating and step in each treatment involved.3. Described the principal engineering properties and industrial application of ferrous and non-ferrous alloys.Apparatus: Optical microscope and 8 alloy specimens (ferrous and non-ferrous alloy).

Figure 1: Optical MicroscopeFigure 2: Alloy Specimens

Theory:1. Introduction:The properties of metals can be changed or controlled by three different processes; strain hardening or cold-working, alloying and heat treatment. All three processes are influenced by and dependent on the crystalline nature of metals. In the study of engineering metal, it is commonly categorized into two big groups; ferrous and non ferrous.Steels are essentially alloys of iron and carbon containing up to 1.5% carbon. By varying the manner in which carbon steels are heated and cooled, different combinations of mechanical properties for steel can be obtained. Heat treatment process is a process of ability to change the properties by applying heat. Such treatment modifies microstructures, producing a variety of mechanical properties that are important in manufacturing, such as improve formability and machinability.Copper and aluminium are categorized as non ferrous metal which have been used in engineering either as in its pure state or as an alloy. The applicants of copper and aluminium have been very wide in the electrical conductors as well as in corrosive environments. Heat treatment of these materials has in many ways improved their properties for specific or specialized applications. The properties of copper and aluminium either in their pure state or as in an alloy can be improved by heat treatment. These changes in properties are the results in the microstructures in these materials through heat treatment. Thus microstructures transformation has influenced the properties of these materials.

2. Alloys: Ferrous and Non-Ferrous:One method of classifying metals is by their content, and one common division is into ferrous metals and non-ferrous metals. Ferrous metals may be pure iron, like wrought iron, or they may be alloys of iron and other elements. Steel, being an alloy of iron and carbon, would therefore be a ferrous metal. Steel is an alloy of iron contains carbon ranging by weight between 0.02% and 2.11%. Cast iron also the type of ferrous which containing about 2.1% to 4% carbon. Ferrous metals are often magnetic, but this property is not in and of itself sufficient to classify a metal as ferrous or non-ferrous. Austenitic stainless steel, a ferrous metal, is non-magnetic, while cobalt is magnetic but non-ferrous Common ferrous metals include the various irons and steels. A non-ferrous metal is important roles in modern technology. Their properties vary widely, almost limitless range of properties and also more costly than iron and steel. Common non-ferrous metals include aluminum, tin, copper, zinc, and brass, an alloy of copper and zinc. Some precious metals such as silver, gold, and platinum are also non-ferrous.

3. Principal engineering properties and industrial application:a. Ferrous:i. Higher strength, hardness, wears resistance, corrosion resistance, hot hardness, and toughness. ii. Some applications are automobile, machinery, surgical instrument, kitchen equipment, cutting tool.

b. Non-Ferrous:i. Corrosion resistance, thermal conduct, high electrical rate, light weight, easy fabricated, high strength, non toxic.ii. Some of its applications are aircraft, cutting tool, jewelry, marine, etc.

4. The phase diagrams and alloy systems.The phase diagram is graph that shows the relation between the solid, liquid, and gaseous states of a substance (see states of matter) as a function of the temperature and pressure. The graph is divided into three regions, one for each of the physical states, and it specifies the range of temperatures at which the substance exists in each state for any value of the pressure.

Iron-Carbon Phase Diagram

The term cast iron refers to a family of ferrous alloy composed of iron, carbon (ranging from 2.11% to about 4.5%), and silicon (up to about 3.5%). Cast iron usually is classified according to their solidification morphology from the eutectic temperature. Cast iron also is classified by their structure: ferritic, pearlitic, quenched and tempered, or austempered.The equilibrium phase diagram relevant to cast iron is shown in figure, where the right boundary is 100% C (that is, pure graphite). The eutectic temperature is 1154oC, and thus, cast irons are completely liquid at temperatures lower than those required for liquid steel. Consequently, iron with high-carbon content can be cast at lower temperatures than cast steel.Cementite is not completely stable; it is metastable, with an extremely low rate of decomposition, it can, however, be made to decompose into alpha ferrite and graphite. The formation af graphite can be controlled, promoted, and accelerated by modifying the composition and the rate of cooling and by the addition of silicon.a. Pearlite:If the ferrite and cementite lamellae in the pearlite structure of eutectoid steel are thin and closely packed, the microstructure is called fine pearlite; if they are thick and widely spaced, it is called coarse pearlite. The different between the two depends on the rate of cooling through the eutectoid temperature. If the rate of cooling is relatively high (as it is in air), fine pearlite is is produced; if cooling is slow (as it is in a fuernace), coarse pearlite is produced.b. Spheroidite:When pearlite is heated to just below the eutectoid temperature and then held at temperature for a period of time. Spheroidites are less conducive to stress concentration. This structure has higher toughness and lower hardness than pearlite structure. It can be cold worked, because the ductile ferrite has high toughness, and sphrroidal carbide particles prevent the initiation of cracks within the material.c. Bainite:Bainite is a very fine microstructure consiating of ferrite and cementite. It can be produced in steels with alloying elements and at cooling rates that are higher than those required transformation to pearlite. This structure generally is stronger and more ductile than pearlitic steels at the same hardness level.d. Martensite:When austenite is colled at a high-rate, its fcc structure ids transformed into body-centered tetragonal structure. This structure can be described as a body-centered rectangular prism which is elongated slightly along one of its principal axes. This structure is called martensite. Martensite transformation takes the placed almost instantaneously because it involves not the diffusion process but a slip mechanism which is a time-dependent phenomenon that is mechanism in other transformations as well as the thermal gradient present in a quenched part cause internal stresses within the body. Experimental Procedure:1. 8 specimens which have been treated under the following conditions are provided to students.2. Each specimens microstructure is required to be observed under the optical microscope.3. The data of the observation to specimen is recorded.

Specimens:1. Ferrous alloy.a. Specimen 1 (X 17)- 0.8% carbon steel, rolled bar, heated for 1 hour at 800 C, furnace cooled (annealed) to room temperature.b. Specimen 2 (X 18) - 0.8% carbon steel, rolled bar, heated for 1 hour at 800 C, cooled in still air (normalized).c. Specimen 3 (X 19) - 0.35% carbon steel bar, furnace cooled from 870 C.d. Specimen 4 (X 20) - 1.3% carbon steel bar, furnace cooled from 970 C.

2. Non-ferrous alloy.a. Specimen 5 (X 12) - Cu 58% / Zn 42%, reheated to 800 C for 1 hour, furnace cooled to 600 C and then water quenched.b. Specimen 6 (X 13) - Cu 58% / Zn 42%, reheatedto 800 C for 1 hour, furnace cooled to room temperature.c. Specimen 7 (X 14) - Aluminium / 4% Copper alloy, sand cast, heated at 525 C for 16 hours and then water quenched.d. Specimen 8 (X 15) - Aluminium / 4% Copper alloy, sand cast, heated at 525 C for 16 hours and then water quenched, reheated at 26 C for 70 hours.

Experimental Result:1. Ferrous alloy:

a. Specimen 1 (X 17) - 0.8% carbon steel, rolled bar, heated for 1 hour at 800 C, furnace cooled (annealed) to room temperature.

b. Specimen 2 (X 18) - 0.8% carbon steel, rolled bar, heated for 1 hour at 800 C, cooled in still air (normalized).

c. Specimen 3 (X 19) - 0.35% carbon steel bar, furnace cooled from 870 C.

d. Specimen 4 (X 20) - 1.3% carbon steel bar, furnace cooled from 970 C.

2. Non-ferrous alloy.

a. Specimen 5 (X 12) - Cu 58% / Zn 42%, reheated to 800 C for 1 hour, furnace cooled to 600 C and then water quenched.

b. Specimen 6 (X 13) - Cu 58% / Zn 42%, reheatedto 800 C for 1 hour, furnace cooled to room temperature.

c. Specimen 7 (X 14) - Aluminium / 4% Copper alloy, sand cast, heated at 525 C for 16 hours and then water quenched.

d. Specimen 8 (X 15) - Aluminium / 4% Copper alloy, sand cast, heated at 525 C for 16 hours and then water quenched, reheated at 26 C for 70 hours.

Discussions:Each of all 8 specimens is observed and discussed base on its microstructure. On the other hand, we also discussed about its characteristics and also application in engineering.

1. The differences between ferrous and non ferrous alloy.Alloys based on iron are called ferrous alloys, and those based on the other metals re called non ferrous alloys.Ferrous Metals mostly contain Iron. They have small amounts of other metals or elements added, to give the required properties. . Steel is an alloy of iron contains carbon ranging by weight between 0.02% and 2.11%. Cast iron also the type of ferrous which containing about 2.1% to 4% carbon. Ferrous metals are often magnetic, but this property is not in and of itself sufficient to classify a metal as ferrous or non-ferrous. Austenitic stainless steel, a ferrous metal, is non-magnetic, while cobalt is magnetic but non-ferrous Common ferrous metals include the various irons and steels.Ferrous Metals are magnetic and give little resistance to corrosion.Non-Ferrous Metals do not contain Iron, are not magnetic and are usually more resistant to corrosion than ferrous metals.

2. Principal engineering properties and industrial application.Iron and its alloy (proncipally steel) account for about 90% of the worlds production of metals mainly because of their combination of good strenght, toughness, and ductility at a relatively low cost. Each metal has special properties for engineering designs and is used after a comparative cost analysis with other metals and materials.

a. Ferrous.Higher strength, hardness, wears resistance, corrosion resistance, hot hardness, and toughness. Some applications are automobile, machinery, surgical instrument, kitchen equipment, cutting tool.b. Non-ferrous.Corrosion resistance, thermal conduct, high electrical rate, light weight, easy fabricated, high strength, non toxic. Some of its applications are aircraft, cutting tool, jewelry, marine, ect.

3. The discussion about the result that we obtained.

a. Ferrous alloy:i. Specimen 1 (X 17) - 0.8% carbon steel, rolled bar, heated for 1 hour at 800 C, furnace cooled (annealed) to room temperature.

This microstructure is called coarse pearlite. The specimen seems to have coarser pearlite that indicates ductility. Annealing is used to induce ductility, relieve internal stresses, refine the structure and improve cold working properties. Eutectoid = pearlite, full annealing.

ii. Specimen 2 (X 18) - 0.8% carbon steel, rolled bar, heated for 1 hour at 800 C, cooled in still air (normalized).

The normalizing process is used to refine the grains (i.e, to decrease the average grain size) and produce a more uniform and desirable size distribution; fine-grained pearlitic steels are tougher than coarsed-grain ones. Carbon diffusion rate decreases, the layers become progressively thinner and are called fine pearlite. For fine pearlite, there are more boundaries through which a dislocation must pass during plastic deformation. Thus the greater reinforcement and restriction of dislocation motion in fine pearlite account for its greater hardness and strength. Air normalizing = fine pearlite, high toughness.

iii. Specimen 3 (X 19) - 0.35% carbon steel bar, furnace cooled from 870 C.

The white constitute is pearlite. Ordinarily, a fine-grained microstructure is desired, and therefore, the heat treatment is terminated before appreciable grain growth has occurred. Hypoeutectoid steel = proeutectiod + pearlite.

iv. Specimen 4 (X 20) - 1.3% carbon steel bar, furnace cooled from 970 C.

The microstructure consists of lamellar eutectoid pearlite. The dark etched phase is cementite and the white phase is ferrite. Ferrite had produced because the alloy was heated over the eutectoid temp. It is then furnace cooled which explain the finer grain structure. It then back to cementite and pearlite structure. Hypoeutectoid steel = austhenic and cementic pearlite .

b. Non-ferrous alloy:i. Specimen 5 (X 12) - Cu 58% / Zn 42%, reheated to 800 C for 1 hour, furnace cooled to 600 C and then water quenched.

Quenching process had caused the specimen or alloy to be more ductile. The elongated needle-liked shape of the ferrite is actually affected by this process. Structures consisting beta phase and alpha phase. Performance needle light structure. Small amount of lead (0.5 to 3%) are added to improve machinability. Annealed cold work condition.

ii. Specimen 6 (X 13) - Cu 58% / Zn 42%, reheatedto 800 C for 1 hour, furnace cooled to room temperature.

This specimen is almost the same with the specimen no 6.but this specimen did not had quenching process so the ferrite did not appear for this specimen. Its means it is less ductile than specimen 5. Performed surface roughness. Consisting 2 phase: alpha and beta.

iii. Specimen 7 (X 14) - Aluminium / 4% Copper alloy, sand cast, heated at 525 C for 16 hours and then water quenched.

The pearlite microstructure was appearing because of water quench process. The GP zones have been formed as disk parallel to the (100) plane of the FCC matrix and at this stage are a few atoms and thick and about 100A diameter. Consisted laminar surfaces

iv. Specimen 8 (X 15) - Aluminium / 4% Copper alloy, sand cast, heated at 525 C for 16 hours and then water quenched, reheated at 26 C for 70 hours.

The microstructure darker than specimen 7 because it had been reheated. Performed laminar surfaces. Specimen reheated to improve their properties and more ductility.

Conclusions:After completing all the tasks; conducting the experiment, discussing the observation of experimental result and completing the report, we can conclude that this experiment is successfully accomplished. It is because; all the group members were able to achieve all the experiment objectives:1. Understand the different between ferrous and non-ferrous alloys from the metallurgical point view.2. Understand the phase diagram of iron-carbon and alloys systems that enables for heat treating and step in each treatment involved.3. Described the principal engineering properties and industrial application of ferrous and non-ferrous alloys.Hence, we are also realizing the importance of compositions in each alloy and heat treatment that involved. Those aspects are playing their role in determine the physical and chemical characteristics.In the real world, characteristics if each material that we are going to use are very important in order to design and produce the safe product and make it long-lasting. Different application of product demands for the material that suitable for it. But, we have to keep in mind that we are not able to produce a material that have all the characteristics that we want. For example, when we want hardness in the material, it decreases the brittleness. Hence, we must balance the characteristics in the material.

References:1. Introduction to Material Science for Engineers; Sixth Edition (James F. Shackelford)2. Foundation of Material Science and Engineering; Second Edition (William F. Smith)3. Material Science and Engineering an Introduction; Second Edition (William D. Callister, Jr)