Mg & its Alloys. Introduction: Fig. ( 37 )

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Jesse Gregory
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Intrductin: Mg is the lightest f the cmmercially engineering metals ( = 1.74 g/cm 3 ) and its structure (c. p. h.). The pure metal is readily available by electrlytic reductin frm seawater.

1 Intrductin: Mg is the lightest f the cmmercially engineering metals ( = 1.74 g/cm 3 ) and its structure (c. p. h.). The pure metal is readily available by electrlytic reductin frm seawater. The pure metal is used primarily as an allying element and as active agent in incendiary devices such as (fire bmb). Mg allys are used where its lw density can be used t max advantage (ex. Ladders, aircraft gear bx husing, laptp cmputer, Tv sets, cellular telephnes). Mg & its allys are generally cnsidered t have pr crrsin resistance. Thus relatively crrsin resistance accunts fr the use f (Mg) as a sacrificial Ande (see fig. 37 aside: Fig. ( 37 )

2 A number f allying elements are utilized t imprve the mechanical prperties f (Mg). Amng these elements are (Al, Zn, Mn), rare earths, Sn, Zr are added t prvide special prperties, Fe, Cu are cnsidered impurities and kept t a min. t avid prblem with crrsin. Ally Designatin & Temper: The Temper designatin is the same as Al. Designatin fr ally cnsists f nt mre than (2) letters representing the allying element specified in the greatest amunt arranged in rder f decreasing (%), fllwed by the respective (%) runded ff t whle number & a serial letters. The letters used t represent allying element are as shwn in table belw:

Ally Designatin & Temper: Table representing Ally elements A Aluminum E Rare Earth Z Zinc B Bismuth F Irn M Manganese C Cpper G Magnesium R Chrmium D Cadmium H Thrium K Zircnium S Silicn T Tin N

3 Ally Designatin & Temper: Table representing Ally elements A Aluminum E Rare Earth Z Zinc B Bismuth F Irn M Manganese C Cpper G Magnesium R Chrmium D Cadmium H Thrium K Zircnium S Silicn T Tin N Nickel Rare Earth is: The rare earth elements are f atmic number (58 71). Bases n this system, the designatin is: AZ63 represents a (Mg) allys cntaining (6% Al & 3% Zn). ZK60A represents a (Mg) allys cntaining (5.5% Zn & 0.45% Zr), the letter (A) as the final letter indicates that this is the first ally whse cmpsitin qualified assignment f the designatin ZK60.

4 Classifying f Mg Allys (Mg + Al) (Mg + Zn) (Mg + Rare earth) (Mg + Th) (Al + Mn) -- AM (Zn + Zr) -- ZK (Rare earth + Zr) EK (Th + Zr) -- HK Pressure tight + Permanent mld casting. Gd cmbinatin f (s, s Y, E%). (Al + Zn) -- AZ Sand casting allys. The effect f Zr is: 1 eliminate the carse grains. 2 Clumnar cast structure. High Zn% requiring very careful cntrl t prduce casting f: - micr prsity. - ht cracks. The additin f (Th) reduce these prblem. Casting allys, suitable fr use upt 500 f, because f imprvement in elevated T prperties by rare earth additin. (Rare earth + Zn) -- EZ Casting allys used fr applicatin in the range f ( ) f better than rare earth metals. (Th + Zn) -- HZ casting allys. (Zn + Th) -- ZH casting allys.

5 Heat Treatment f Mg Allys 1 Slutin Treatment. Cast allys 2 Artificial aging. Partial at T (325 f) (12 hr) Cmplete T (450 f) (5 hr) AC (Air Cled) 3 Stabilizing. At (500 f) (4 hr) air cled Wrught allys 1 Stress relief at 500 f fr (15) min. fr allys M1, A3, P, AZ. 2 Fr ZK60, aging at T (300 f) fr (24) hr, air cled. Air cled t minimize grwth when the casting are used at elevated T. Relief f residual stress. Relief f stress that may develp by rapid cling. Slutin treatment fr allys: AM AZ HK (790 f) fr 20 hr, cling medium strng air (atmsphere with at least 0.5% SO 2 is required). (740 f) fr 10 hr, air cled, age at (450 f) fr 5 hr air cled. f) fr 1 hr. (1050 f) fr 2 hr, air cled (fr Casting) fr sheet (stress relieved after welding at (650

Chemistry, wt % C O S Mn P Fe 0,05 0,17 0,006 0,008 0,025 99,4+

Chemistry, wt % C O S Mn P Fe 0,05 0,17 0,006 0,008 0,025 99,4+ is a very high strength, highly-cmpressible irn pwder designed fr medium P/M applicatins. Cmpressibility- can be single pressed t densities up t 7.0 g/cm3. Higher strength, higher parts extend the perfrmance