We elucidate here the mechanistic contribution of the interplay between microstructural constituents and plastic deformation behavior in hot-rolled Fe-0.2C-11Mn-xAl steels containing 2-6 wt.% Al. The decrease in austenite fraction with increase in Al-content was accompanied by decrease in tensile strength, while the δ-ferrite content and ductility increased. 2Al steel was characterized by ultrahigh ultimate tensile strength (UTS) of 1407 MPa, while 6Al steel exhibited extremely high total elongation (TE) of 65%. The superior ductility in 6Al steel is attributed to cumulative contribution of transformation induced plasticity (TRIP) effect and twinning induced plasticity (TWIP) effect. The increase in soft δ-ferrite phase with low microhardness led to increase in TE and decrease in UTS and work hardening rate.

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The shear strength of materials after extensive plastic flow under a superimposed high hydrostatic stress component is most conveniently studied by means of Bridgman opposed anvils between which thin disk-shaped samples are sheared through relative rotation. A newly designed apparatus of this type permits, for the first time ever, the monitoring of sample thickness during shearing and thus the obtaining of averaged shear stress/shear strain curves. Such relations are needed for the better understanding of geological processes, behavior under shock or explosive impact, and of the surface layers during friction and wear, among others. A semiquantitative analysis shows that nonuniform pressure distribution in the samples cannot significantly falsify the results. It is concluded that distributed shearing is always accompanied by sample thinning and that, conversely, slippage between anvils and specimens is indicated whenever the sample stops thinning during rotation. Such slippage can be greatly reduced by raising the friction coefficient through etching of samples and/or anvils, but it apparently occurred undiscovered in previous studies, partly after initial distributed shearing. Further, in previous results slippage between directly contacting anvils was frequently mistaken for sample shearing. Additionally, the previously neglected sample material being extruded during shearing can falsify results, as can "turbulent flow" initiated at sample perforation. Correspondingly all prior data gained with Bridgman apparatuses are suspect. Present best results indicate (i) that in metals ordinary dislocation glide but apparently with strongly increased Peierls-Nabarro stresses continues to the highest pressures studied, (ii) that independent of thermal activation workhardening may cease at high strains, and (iii) that "turbulent flow" resulting through sample perforation or when the sample thickness decreases below a critical value, can give rise to mechanical alloying. The majority if not all of the data by Bridgman as well as Vereshchagin et al. probably involved such mechanical alloying. When plotted versus pressure in units of shear moduli, the apparent coefficients of friction of the five cubic metals examined so far follow nearly the same curve but they are lower for metals of lower symmetry.

Effect of ball scribing on relative permeability of conventional grain-oriented (CGO) and high permeability grain-oriented (HGO) electrical steel was investigated. The samples were scribed with spacing of 2 mm, 4 mm, 8 mm and 16 mm. The results show that after ball scribing with 16 mm width at 1.0 T, relative permeability of both CGO and HGO steels was increased by 109% and 80%, respectively. Relative permeability rises as the scribing space increases, with the movement of the peak value of relative permeability to a higher flux density. Relational models describing relative permeability and flux density were constructed with high accuracy based on experimental data. The experimental data curves were analyzed during the magnetizing process.

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