The capacity for hardening is an invaluable property not only in regard to cutting-tools, but also in prolonging the life of parts subjected to severe friction.
The power of being hardened by sudden cooling, because the essence of this hardening is the retention of the (3 state.
That the ancients should have discovered an art of hardening bronze is grossly improbable, first because it is not to be hardened by any simple process like the hardening of steel, and second because, if they had, then a large proportion of the ancient bronze tools now known ought to be hard, which is not the case.
Its combination of ductility with strength and hardening power has given it very extended use for the armour of war-vessels.
The plate is then by Krupp's process heated so that its impact face is above while its rear is below the hardening temperature, and the whole is then cooled suddenly with sprays of cold water.
Silicic hardening does not begin till the full height is nearly attained.
Steel is iron which is malleable at least in some one range of temperature, and also is either (a) cast into an initially malleable mass, or (b) is capable of hardening greatly by sudden cooling, or (c) is both so cast and so capable of hardening.
The shares, when made of the same material, required constant sharpening; this necessity was removed by the device, patented by Robert Ransome in 1803, of chilling and so hardening the under-surface of the share; the upper surface, which is soft, then wears away more quickly than the chilled part, whereby a sharp edge is always assured.
The rock on the surface is as hard as flint, but underneath it gradually softens and furnishes an admirable stone for building which can be sawn into blocks of any size, hardening on exposure to the atmosphere.
The hardening of the extremities of the fibro-vascular tissue is the cause of the spiny margin of many leaves, such as the holly, of the sharp-pointed leaves of madder, and of mucronate leaves, or those having a blunt end with a hard projection in the centre.