Kinetics of compressive creep in sand cast commercial line-based alloys No. 3 and No. 5

Authors

  • A.A. Mir
  • S. Murphy

Abstract

Compressive creep tests have been carried out on two sand cast commercial zinc-rich alloys in the stress range 20 to 100 MPa, and at temperatures from 70 to160°C. A parametric relationship was obeyed, of the form: In t = C' - n(lna) + Q/RT, where C' is a constant, a the applied stress, t the time of test, n the stress exponent, Q the activation energy, R the gas constant, and T is the absolute temperature.

The primary creep strain increased with copper content and was therefore higher in alloy No5, but the secondary creep rates of No5 were much lower than those of No3. Similarly, time to 1 % creep strain was greater for No5. Thus, alloy No5 was found to have a total creep contraction significantly lower than No3 under all testing conditions due to its lower secondary creep rates. The results and structure of alloys showed that creep in alloy No3 is controlled by dislocation climb process, whereas in alloy No5 the creep controlling mechanism is the climb of dislocations over second-phase  particles.

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Published

2013-09-04

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Articles