HEAT TREATMENT OF NON-FERROUS METALS AND ALLOYS BY JITENDRA

CONTENTS Introduction 01 Aluminium and Its Alloys 02 Magnesium Alloys 03 Titanium Alloys 04 Copper and Its Alloys 05

INTRODUCTION ☼Non-ferrous metals and alloys form an Important group of materials of industrial importance. ☼Aluminium, copper, lead, magnesium, nickel and titanium and alloys of all these metals are the significant non-ferrous metals and alloys. ☼In addition, there are also a few special purpose non-ferrous metals and alloys. ☼By heat treatment of these metals and alloys, the desired combination of properties is achieved. ☼This, in turn, has gone a long way in their adoption for commercial use.

ALUMINIUM AND ITS ALLOYS ☼Aluminium and its alloys are used in a variety of cast and wrought forms and conditions of heat treatment. Forging, sections, extrusions,sheet, plate, strip, foil and wire are some examples of wrought form, while castings are available as sand, pressure and gravity die castings. ☼The AAA(Aluminium Association of America) has classified the wrought aluminum alloys according to a four digit system. The first digit identifies alloy type. The second digit shows the specific alloy modification The last two digits indicate the specific aluminium alloy or the purity level in case of pure aluminium. Reference no. 2

DESIGNATION OF ALUMINIUM ALLOYS Alloy numberMajor alloying element(s) 1 XXXCommercially pure aluminium (>99%) 2 XXX Copper 3 XXXManganese 4 XXXSilicon 5 XXXMagnesium 6 XXXMagnesium, silicon 7 XXXZinc 8 XXXOther elements such as nickel, titanium,chromium, lead, bismuth 9 XXXUnassigned Reference no. 5

HEAT TREATABLE ALUMINIUM ALLOYS I.2 XXX series of Al-Cu alloys and Al-Cu-Mg alloys. In RR 58 alloy(2618 T16) copper and magnesium improve the strength by age hardening. II. 6 XXX series include AL-MG-Si type alloys. These are used as medium strength structural alloys with added advantages of good weld ability, corrosion resistance and immunity to stress corrosion cracking. III. 7 XXX series include Al-Zn, Al-Zn-Mg, and Al-Zn-Mg-Cu type alloys. Alloys of this series show pronounced potentiality for age hardening. There is raid decrease in solubility of zinc with decrease in temperature.

MAGNESIUM ALLOYS ☼Magnesium(wrought and cast) alloys are very popular in aerospace industries because of their low density(1.8 gm /cc), high strength to width ratio, good damping capacity, ease of machinability, and relatively high thermal and electrical conductivity. These alloys are processed in the form of castings, forgings and extrusions, and show good dimensional stability up to 100c. ☼ Wrought form of magnesium alloys are used in aircraft fuel tanks,ducts, wings and flaps in the form of sheets. The extrusions are used in seat frames. Forging ate used in aircraft engine bearing caps, housings and shocker arm supports. Reference no. 3

HEAT TREATMENT OF MAGNESIUM ALLOYS  Annealing and Stress Relieving : Depending on composition, wrought magnesium alloys which have been strain hardened to various degrees, i.e., which are in different tempers, can be annealed in the temperature range c by soaking for 1 or 2 hours.  Solution Heat Treatment : The alloying elements dissolve into solution and form a single-phase solid solution. solutionizing temperature for magnesium cast alloys varies from 350. C to 490. C and soaking time varies from 8 hours to 24 hours.  Precipitation Hardening: This treatment is carried out after solutionizing treatment so that the precipitation of some fine, coherent particles takes place. Ageing temperature varies from 130. C to 230. C. Ageing is carried out for 5-16 hours. In some cases, ageing time may be up to 48 hours.

TITANIUM ALLOYS ☼Titanium and its alloys give a variety of light weight strong materials with good fatigue and corrosion resistance. It is used as substitute for aluminium alloys in aircraft structure subjected to service in the temperature range C. ☼There are two allotropic forms of titanium, namely, alpha (α) titanium having a close packed hexagonal crystal structure, up to 882. C, and beta (β) titanium having body centered cubic structure which is stable above 882. C.Commercially pure titanium contains residual amounts of oxygen, nitrogen, carbon, iron, and so on. Reference no. 4

HEAT TREATMENT OF TITANIUM ALLOYS  Stress Relieving: Titanium and titanium alloys are stress relieved to minimize the undesirable residual stresses due to cold working, non-uniform hot forging and solidification. Removal of these stresses helps in maintaining stability of shape and removes unfavourable conditions, e.g. the loss of compressive yield strength (Bauschinger effect).  Annealing: Annealing improves fracture toughness, ductility, dimensional and thermal stability and creep resistance. Different types of annealing treatment given to titanium alloys include (i) mill annealing, (ii) duplex annealing, (iii) triplex annealing, (iv) recrystallization annealing, and (v) beta annealing.  Solution Treating and Ageing: α-β and β-alloys are solution heat treated and aged to obtain a wide range of strength levels. High temperature β-phase is unstable at lower temperatures. Higher ratio of β is produced by heating an α-β alloy to the solution treating temperature. By quenching, the proportion of phases is maintained. Decomposition of metastable β-phase takes place during subsequent ageing. This results in improved strength levels.

COPPER AND ITS ALLOYS ☼Copper and its alloys find wide application in industries as electrical conductor, fuel and oil lines, bearings, auto mobile radiators, pressure vessels, and so on. They are good electrical conductors, have reasonable strength coupled with good corrosion resistance, and are non-magnetic. ☼Heat treatment processes which are relevant to copper and copper alloys include homogenizing, annealing and stress relieving. Beryllium bronzes are precipitation hardenable alloys. Reference no. 6

(Contd…  Heat Treatment of Copper: In case of pure copper, the heat treatment process which is adopted is annealing. The purpose of annealing is to achieve the original ductility and softness in cold-worked copper. Pure copper is annealed at about 600 degree Celsius. After holding at this temperature for sometime,copper is quenched in cold water.  Heat Treatment of Brasses: Like pure copper, brasses are also subjected to recrystallization annealing treatment after cold working. By annealing above recrystallization temperature, the original degree of ductility and toughness can be restored in the cold-worked brass. Annealing may be carried out by heating the cold-worked brass at a temperature between 650 and 700. C.  Heat Treatment of Bronzes: Beryllium bronzes respond to precipitation heat treatment and contain % beryllium. Other type of bronzes are not given any heat treatment except annealing at about 500 degree celsius. Copper-beryllium alloys are solutionized at 800 degree Celsius for about half an hour, followed by quenching in water.

REFERENCES 1.Chapter no. 16th HEAT TREATMENT Principles and techniques (Second Edition); THE AUTHORS: T.V. Ranjan, C.P. Sharma, Ashok Sharma. 2. LWy4Nq0Cgfk%2FVe_YPwDzzvI%2FAAAAAAAAALc%2FtkAU_7XQLWM%2Fs1600%2Funtitl ed.JPG&imgrefurl=http%3A%2F%2Fblog.luckygroup.com%2F2015%2F09%2Fimportance-of- aluminium-alloys-and-their-various- functionalities.html&docid=3zLYh6OdCuavzM&tbnid=8t7_he7zZxqFsM%3A&vet=10ahUKEwj G7amkgtPeAhVJro8KHT_6DI0QMwiXASgmMCY..i&w=410&h=309&client=opera&bih=627&bi w=1326&q=ALUMINIUM%20ALLOYS&ved=0ahUKEwjG7amkgtPeAhVJro8KHT_6DI0QMwiX ASgmMCY&iact=mrc&uact=8 3. %2FSell%2Fautomobile-parts-magnesium-alloy-die-casting-u p jpg&imgrefurl=http%3A%2F%2Fwww.worldbid.com%2Fmanufacturing%2Fmanufac turing-casting-casting%2Fautomobile-parts-magnesium-alloy-die-casting- i html&docid=PYwYLtzjxlA- EM&tbnid=uRx9ijP_RJmy8M%3A&vet=12ahUKEwi93e3739PeAhWKYo8KHdkXC1Y4ZBAzKC 8wL3oECAEQMA..i&w=338&h=346&bih=775&biw=1536&q=magnesium%20alloys&ved=2ahU KEwi93e3739PeAhWKYo8KHdkXC1Y4ZBAzKC8wL3oECAEQMA&iact=mrc&uact=8

REFERENCES(Contd… 4. ompanylogo%2Fproducts%2F%2F jpg&imgrefurl=https%3A%2F%2Fomanyellowpagesonline.co m%2Fco-pearl-overseas%2F %2Fproducts%2F805769%2Ftitanium- alloys.html&docid=DThrNJn_IezfHM&tbnid=7TEtNjAg3C0tCM%3A&vet=10ahUKEwijzMu- 4dPeAhXDsY8KHUiFBPoQMwiYASgxMDE..i&w=250&h=183&itg=1&bih=775&biw=1536&q=titanium%20alloy s&ved=0ahUKEwijzMu-4dPeAhXDsY8KHUiFBPoQMwiYASgxMDE&iact=mrc&uact=8 5. Table 16.1,page no. 278 Chapter no. 16th HEAT TREATMENT Principles and techniques (Second Edition); THE AUTHORS: T.V. Ranjan, C.P. Sharma, Ashok Sharma 6. %2Feuro.jpg&imgrefurl=https%3A%2F%2Fcopperalliance.org.uk%2Fknowledge- base%2Feducation%2Feducation-resources%2Fcopper-alloys-coinage%2F&docid=GO0yg6- yTejJNM&tbnid=Iy2AvrDxvfevlM%3A&vet=12ahUKEwjksruv_NPeAhWRWX0KHdJrCy84ZBAzKF4wXnoECAE QXw..i&w=353&h=386&bih=775&biw=1536&q=copper%20and%20its%20alloys&ved=2ahUKEwjksruv_NPeAh WRWX0KHdJrCy84ZBAzKF4wXnoECAEQXw&iact=mrc&uact=8

T H A N K S