Determining of Flow Curve of Magnesium Az61 Alloy Using Ring Test

A common method for the determination of flow curves is the application of a compression test. Using this method, friction in the interface between the die and the specimen leads to a bulging of the sample and thereby to an inhomogeneous stress and strain state. The calculation of the flow stress from experimentally determined force–displacement curves implies a uniaxial stress state, but this will produce an error because of the above-mentioned bulging, when friction occurs. One method of avoiding these sources of error is to use the bulge correction factor method, but this method can not cover errors at large strain. Another strategy, described in this paper, applies numerical correction factor method, the calculation of the flow curve being done by the use of an iterative procedure, applying a corrective function. This paper presents a complete characterisation of the AZ61 magnesium alloy flow curve at temperature ranging between 200°C and 240°C . Ring tests are utilised to determine the flow curve sensitivity to temperature and strain rate, and numerical correction factor was employed to reduce errors . By using numerical sigmoid curves more accuracy will be obtained, shown at load-displacement curves. Keywords- High Temperature, AZ61, Flow Curve, Numerical Method, Ring Test