Wear Performance of a Laser Surface Hardened ASTM 4118 Steel

In this investigation ASTM 4118 steel was treated by using pulse Nd: YAG laser with wave length 1064nm and pulse duration 100ns. In order to assess the new tribological properties of laser surface hardened ASTM 4118 steel, the wear resistance between specimens treated with laser and those of conventionally hardened under dry sliding conditions was compared. The change of wear mechanisms in laser hardened 4118 steel resulted in distinct difference in wear rates. The results showed that quenched zones not only had sufficient depth of hardening and higher hardness, but had more retained austenite and finer carbides because of a higher degree of carbide dissolution. Laser surface hardened ASTM 4118 steel specimens exhibited superior wear resistance to their conventionally hardened specimens due to the change in the microstructure hardening, high hardness. The wear mechanism for both the laser quenched layer and conventionally hardened layer was highly similar, generally involving adhesive wear mechanism , material transfer, wear induced oxidation and plowing. Also the results of hardness show that increases with increasing of laser energy by 70%

Effectiveness of Naphthalene in Grain Refinement of Commercially Pure Aluminum and Zinc Ingot Castings

It is well established that the properties of cast metals are greatly improved by refinement of their grain size. The method employed in this study for the refinement of grain size of commercially pure aluminum and zinc castings is inoculation of naphthalene in powder form to the mould prior to pouring the molten metal. The results show that the addition of naphthalene remarkably suppresses the formation of columnar grains and refines the structure. Increasing the amount of naphthalene addition also minimizes and may eliminate the formation of the shrinkage cavity. Furthermore, the ability of castings for mechanical working increases as the naphthalene addition increase

One Parameter Composite Semigroups of Linear Bounded Operators in Strong Operator Topology of Schatten Class Cp

For semigroups of linear bounded operators on Hilbert spaces, the problem of being in Cp , 0 Keyword