This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Shock hardening" – news · newspapers · books · scholar · JSTOR(March 2010) (Learn how and when to remove this message)
Shock hardening is a process used to strengthen metals and alloys, wherein a shock wave produces atomic-scale defects in the material's crystalline structure. As in cold work, these defects interfere with the normal processes by which metallic materials yield (plasticity), making materials stiffer, but more brittle. When compared to traditional cold work, such an extremely rapid process results in a different class of defect, producing a much harder material for a given change in shape. If the shock wave applies too great a force for too long, however, the rarefaction front that follows it can form voids in the material due to hydrostatic tension, weakening the material and often causing it to spall. Since voids nucleate at large defects, such as oxide inclusions and grain boundaries, high-purity samples with a large grain size (especially single crystals) are able to withstand greater shock without spalling, and can therefore be made much harder.
Shock hardening has been observed in many contexts:
Explosive forging uses the detonation of a high explosive charge to create a shockwave. This effect is used to harden rail track cast components[1] and, coupled with the Misnay-Schardin effect, in the operation of explosively forged penetrators. Greater hardening can be achieved by using a lower quantity of an explosive with greater brisance, so that the force applied is greater but the material spends less time in hydrostatic tension.
Laser shock, similar to inertial confinement fusion, uses the ablation plume caused by a laser pulse to apply force to the laser's target.[2] The rebound from the expelled matter can create very high pressures, and the pulse length of lasers is often quite short, meaning that good hardening can be achieved with little risk of spallation. Surface effects can also be achieved by laser treatment, including amorphization.
Light-gas guns have been used to study shock hardening. Although too labor-intensive for widespread industrial application, they do provide a versatile research testbed. They allow precise control of both magnitude and profile of the shock wave through adjustments to the projectile's muzzle velocity and density profile, respectively. Studies of various projectile types have been crucial in overturning a prior theory that spallation occurs at a threshold of pressure, independent of time. Instead, experiments show longer-lasting shocks of a given magnitude produce more material damage.
^The service life of frogs can be increased threefold when treated with this technique: Meyers, Marc A. (1994). Dynamic behavior of materials. New York: John Wiley. pp. 5, 382, 570. ISBN 978-0-471-58262-5.
^Goswami, Debkalpa; Munera, Juan C.; Pal, Aniket; Sadri, Behnam; Scarpetti, Caio Lui P. G.; Martinez, Ramses V. (2018-05-18). "Roll-to-Roll Nanoforming of Metals Using Laser-Induced Superplasticity". Nano Letters. 18 (6): 3616–3622. Bibcode:2018NanoL..18.3616G. doi:10.1021/acs.nanolett.8b00714. ISSN 1530-6984. PMID 29775318.
Shockhardening is a process used to strengthen metals and alloys, wherein a shock wave produces atomic-scale defects in the material's crystalline structure...
Cryogenic hardening is a cryogenic treatment process where the material is cooled to approximately −185 °C (−301 °F), usually using liquid nitrogen. It...
water quenching. There are six groups of tool steels: water-hardening, cold-work, shock-resistant, high-speed, hot-work, and special purpose. The choice...
than one that has not been through cold hardening before. Light doesn't control the onset of cold hardening directly, but shortening of daylight is associated...
well in this. A common commercial use of plastic explosives is for shockhardening high manganese percentage steel, a material typically used for train...
fatigue, and stress corrosion cracking. Laser shock peening can also be used to strengthen thin sections, harden surfaces, shape or straighten parts (known...
and centrifugal forces, the fuze design also needed to utilize many shock-hardening techniques. These included planar electrodes, and packing the components...
are different kinds of heat treatment processes such as edge hardening or complete hardening. The cross-section of the switch blades also influences performance...
Heat shock proteins (HSPs) are a family of proteins produced by cells in response to exposure to stressful conditions. They were first described in relation...
malleability of fcc metals. Twin boundaries are partly responsible for shockhardening and for many of the changes that occur in cold work of metals with...
Vulcanization (British English: Vulcanisation) is a range of processes for hardening rubbers. The term originally referred exclusively to the treatment of...
Quench polish quench (QPQ) is a specialized type of nitrocarburizing case hardening that increases corrosion resistance. It is sometimes known by the brand...
few sheets of steel, and it requires a special salt bath. Case hardening processes harden only the exterior of the steel part, creating a hard, wear-resistant...
ground or water. The ground shock can damage or destroy hardened structures. In water, the shock is damaging to nearby vessels and may also produce a surface...
flame hardening and induction hardening techniques, the steel is quickly heated to red-hot in a localized area and then quenched. This hardens only part...
lessened due to its inability to transmit shock to the target. Further thinking on the subject envisions a hardened penetrator using kinetic energy to defeat...
also cope with the underpressure that lasts for several seconds after the shock wave passes, and block radiation. A bunker's door must be at least as strong...
the isotropic hardening laws, and those of Kratochvil, Malinini and Khadjinsky, Ponter and Leckie, and Chaboche for the kinematic hardening laws. Perzyna...
abrasion. When a metal undergoes strain hardening its yield strength increases but its ductility decreases. Strain hardening actually increases the number of...
against hardened surfaces. In an attack on the Valentin U-Boat pens at Farge, two Grand Slams went through the 15 ft (4.5 m) reinforced concrete hardening—equalling...