Fundamental and Applied Aspects of Noble Gas Bubbles in Steel
This paper reports a study aimed at improving the wear performance of common steels by noble gas ion implantation and laser melting. It turns out that the shear stress field of a noble gas bubble in a metastable austenitic steel (SS 304) induces a martensitic transformation, provided that bubble size and pressure are large enough. The wear resistance decreases with increasing dose. In laser melted stable austenitic steel (RCC) subsequently implanted with noble gas ions, transmission electron micrographs has provided clear evidence of the formation of a large number of bubbles, Orowan looping and pinning of dislocations by these bubbles. The wear rate decreases with increasing dose. However, this is certainly not a general observation of laser melted-ion implanted steels. The low carbon steel CK22 for instance shows a martensitic structure after laser melting with a high dislocation density. In contrast to RCC, the wear rate increases with increasing dose suggesting that moving dislocations are interacting with forest dislocations rather than with the noble gas bubbles.
KeywordsWear Rate Martensitic Transformation Orientation Relationship Bubble Size Thin Foil
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