Hardening (metallurgy)

About: Hardening (metallurgy) is a research topic. Over the lifetime, 25584 publications have been published within this topic receiving 376012 citations.

Uniaxial Ratchetting of 316FR Steel at Room Temperature— Part I: Experiments

Abstract: Uniaxial ratchetting characteristics of 316FR steel at room temperature are studied experimentally. Cyclic tension tests, in which maximum strain increases every cycle by prescribed amounts, are conducted systematically in addition to conventional monotonic, cyclic, and ratchetting tests. Thus hysteresis loop closure, cyclic hardening and viscoplasticity are discussed in the context of constitutive modeling for ratchetting. The cyclic tension tests reveal that very slight opening of hysteresis loops occurs, and that neither accumulated plastic strain nor maximum plastic strain induces significant isotropic hardening if strain range is relatively small. These findings are used to discuss the ratchetting tests. It is thus shown that uniaxial ratchetting of the material at room temperature is brought about by slight opening of hysteresis loops as well as by viscoplasticity, and that kinematic hardening governs almost all strain hardening in uniaxial ratchetting if stress range is not large.

A coplanar Orowan loops model for dispersion hardening

Abstract: When an internally oxidized Cu-Al2O3 alloy with Al2O3 particles of diameter <500 A is plastically deformed, each particle is likely to be intersected by only one or two slip planes. Consequently, at low temperatures, Orowan loops are expected to form coplanar pile-ups rather than the vertical stacks assumed in recent theories of dispersion hardening. The arrangement of concentric Orowan loops is described and the contribution they make to the flow stress of a dispersion-hardened alloy is calculated. To a first approximation, the three principal components, the image stress, the long-range stress and the bowing stress are all proportional to the number of Orowan loops. The flow stress of an alloy has two other components: the interaction stress between gliding dislocations and a further bowing stress from stacks of prismatic loops. The components are combined to describe the stress-strain curve in forward and reverse flow and it is concluded that the experiments are best described by a hybrid mode...

Dislocation Networks and the Microstructural Origin of Strain Hardening

Abstract: When metals plastically deform, the density of line defects called dislocations increases and the microstructure is continuously refined, leading to the strain hardening behavior. Using discrete dislocation dynamics simulations, we demonstrate the fundamental role of junction formation in connecting dislocation microstructure evolution and strain hardening in face-centered cubic (fcc) Cu. The dislocation network formed consists of line segments whose lengths closely follow an exponential distribution. This exponential distribution is a consequence of junction formation, which can be modeled as a one-dimensional Poisson process. According to the exponential distribution, two non-dimensional parameters control microstructure evolution, with the hardening rate dictated by the rate of stable junction formation. Among the types of junctions in fcc crystals, we find that glissile junctions make the dominant contribution to strain hardening.