Table 2. Physical and Mechanical Properties of Zinc Pressure Diecasting Alloys


Physical Property Density (lb./cu. in.)


Solidifi cation Shrinkage (%) Solidifi cation Temp. Range (F) Thermal Expansion (in./in. –F) Specifi c Heat Capacity (btu/lb.-F) Specifi c Heat Capacity (btu/cu. in.-F) Electrical Conductivity (%IACS) Electrical Resitivity (Micro ohm-in.) Ultimate Tensile Strength (ksi) Yield Strength (ksi) Elongation (%)


Hardness (Brinell-500 kg) Shear Strength (ksi)


Compressive Strength (0.1% offset) (ksi) Impact Energy


(unnotched bar 0.25 in. x 0.25 in.) (J) Fatigue Strength (5x108


cycles) (ksi) 2


0.24 1.25


734-715 15.2x10-6 0.1


0.024 25 —


48 — 2


98 46 93


6.8 8.5


3


0.24 1.17


728-719 15.2x10-6 0.1


0.024 27


2.5 35 —


16 72 31 60


55.6 6.9


5


0.24 1.17


Alloy Designation 7


0.24 1.17


727-717 728-717 15.2x10-6 0.1


0.024 26


2.6 39 —


13 80 38 87


54.2 8.2


Source: Engineering Properties of Zinc Alloys, International Lead Zinc Research Organization Inc.


groups. The fi rst group includes the alloys commonly known as Numbers 2, 3, 5 and 7. All of these alloys have 4% aluminum as the primary alloying constituent with 0.099% or less magnesium to control intergranular corrosion. The difference between all of these alloys (except for Number 7) is the percentage of copper as the second alloying element. The al- loys with the highest copper have the highest hardness but the lowest impact strength. Number 7 achieves improved properties through higher purity and 0.005-0.02% nickel. The second alloy group consists of ZA-


8, ZA-12 and ZA-27, in which the number represents the percentage of aluminum in the alloy. The ZA alloys have superior hardness, wear and creep resistance that increase with the aluminum content. The third alloy group consists of a sin-


gle alloy—ACuZinc—which has copper as the primary alloying element. This alloy is patented by General Motors. ACuZinc has superior mechanical properties compared to the other zinc alloys. It has greater hard- ness (118 Brinell), tensile strength (59 ksi) and even a higher modulus (14.5x106


statement that precisely defines the product functions to be performed. After product function has been de- fined, a configuration compatible with the diecasting process and the selected


alloy must be developed. Alloy selec- tion is based primarily on the required mechanical, physical and chemical prop- erties of the component. For a product configuration optimized for diecasting,


0.024 27 —


41 —


18 67 31 60


55.6 6.8


15.2x10-6 0.1


ZA-8


0.227 1.1


759-707 12.9x10-6 0.104 0.024 27.7 2.4 43 32 20 91 33 25


17 15


ZA-12 0.218 1.25


810-710 13.4x10-6 0.107 0.023 28.3 2.4 45 35 10 91 34 27


19 —


ZA-27 0.181 1.25


903-708 14.4x10-6 0.125 0.023 29.7 2.6 52 46


3.0


100 37 37


2.2 21


psi).


But its greatest superiority is in its creep resistance (710 hours to fracture at 3,600 psi and 300F). It is nearly seven times as creep resistant as the ZA-8 alloy. Table 2 lists the as-cast physical and


mechanical properties of the first two groups of zinc alloys.


Design Principles Creative design of a diecast zinc


component must begin with a clear 2010 Casting sourCe DireCtory Metal Casting Design & PurChasing 41


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48  |  Page 49  |  Page 50  |  Page 51  |  Page 52  |  Page 53  |  Page 54  |  Page 55  |  Page 56  |  Page 57  |  Page 58  |  Page 59  |  Page 60  |  Page 61  |  Page 62  |  Page 63  |  Page 64  |  Page 65  |  Page 66  |  Page 67  |  Page 68  |  Page 69  |  Page 70  |  Page 71  |  Page 72  |  Page 73  |  Page 74  |  Page 75  |  Page 76  |  Page 77  |  Page 78  |  Page 79  |  Page 80  |  Page 81  |  Page 82  |  Page 83  |  Page 84  |  Page 85  |  Page 86  |  Page 87  |  Page 88  |  Page 89  |  Page 90  |  Page 91  |  Page 92  |  Page 93  |  Page 94  |  Page 95  |  Page 96  |  Page 97  |  Page 98  |  Page 99  |  Page 100  |  Page 101  |  Page 102  |  Page 103  |  Page 104  |  Page 105  |  Page 106  |  Page 107  |  Page 108  |  Page 109  |  Page 110  |  Page 111  |  Page 112  |  Page 113  |  Page 114  |  Page 115  |  Page 116  |  Page 117  |  Page 118  |  Page 119  |  Page 120  |  Page 121  |  Page 122  |  Page 123  |  Page 124  |  Page 125  |  Page 126  |  Page 127  |  Page 128  |  Page 129  |  Page 130  |  Page 131  |  Page 132  |  Page 133  |  Page 134  |  Page 135  |  Page 136  |  Page 137  |  Page 138  |  Page 139  |  Page 140  |  Page 141  |  Page 142  |  Page 143  |  Page 144  |  Page 145  |  Page 146  |  Page 147  |  Page 148  |  Page 149  |  Page 150  |  Page 151  |  Page 152  |  Page 153  |  Page 154  |  Page 155  |  Page 156  |  Page 157  |  Page 158  |  Page 159  |  Page 160  |  Page 161  |  Page 162  |  Page 163  |  Page 164  |  Page 165  |  Page 166  |  Page 167  |  Page 168  |  Page 169  |  Page 170  |  Page 171  |  Page 172  |  Page 173  |  Page 174  |  Page 175  |  Page 176  |  Page 177  |  Page 178  |  Page 179  |  Page 180  |  Page 181  |  Page 182  |  Page 183  |  Page 184  |  Page 185  |  Page 186  |  Page 187  |  Page 188  |  Page 189  |  Page 190  |  Page 191  |  Page 192