Micro-Structure Evolution of SAF2205 Steel Subjected to Single Direction Torsion at Room Temperature

The microstructure morphology of SAF2205 steel during single direction torsion is studied at room temperature by optical microscope. The microstructure evolution indicates that different austenite morphologies on selected longitudinal sections are observed from the subsample close to clamp end, the subsample close to the fracture end and the subsample from the undeformed specimen. The austenite is elongated gradually on longitudinal sections which caused by shear stress. Concurrently, the elongation degree is more obvious in L1 section (near to the center of the sample) than that of L2 section (away from the center of the sample), which is attributed to the gradient distribution of plastic strain. The finite element analysis shows the plastic strain distribution law of the torsional deformation and the results from the fracture appearance indicate the dimples with different depths and types are observed.

A Direct Correlation of Strength With Impact Velocity in the Taylor Test

This paper presents a method for analyzing the results of a Taylor impact test. From post-mortem measurements of final specimen length and final undeformed specimen length the dynamic material strength on impact, σo, is correlated with impact velocity, V, through the relation σo=−Y−BV2 where Y and B are presumed to be material constants. This relation provides a rate-dependent constitutive law that is potentially useful in situations such as rod penetration, for example.

Methods for the Determination of Internal Energy Contribution to Rubber Elasticity

In order to determine exactly the contribution of internal energy component to retractive force (fe/f), two methods (one is Single Specimen Method [Successive Contraction Method] and the other Multi Specimen Method), two different reference lengths (one is the initial length of undeformed specimen and the other the final length including permanent set), and two instruments of different type (one is automatic balance type relax-o-meter [ROM] and the other tensile tester) were examined by using natural rubber, cis-1,4-polyisoprene, and polyurethane rubber. The apparent mechanical and thermo-dynamic properties were significantly dependent upon these methods and reference lengths. In spite of the variation of C1 and C2 in Mooney-Rivlin plot, fe/f was almost unaffected and the sign of this value coincided with that expected from the chain conformation as far as ROM-Single or Multi Specimen Method and the final length were adopted. The influences of permanent set, the time used to attain equilibrium, etc. were also discussed.