Hydrogen-induced defects of AISI 304 stainless steel were investigated by measuring variable energy Doppler broadening energy spectra (DBES) of positron annihilation and positron annihilation lifetime (PAL). Experimental results showed that hydrogen damage starting from the surface to the bulk has a significant variation with depth. The increase in S-parameter near the surface after hydrogen-charging mainly comes from hydrogen damage; however the increase in Sparameter in the bulk after hydrogen-charging mainly comes from structural defects (e.g. dislocations) induced due to hydrogen-charging. Positron lifetime analysis of two lifetime components is also discussed, and the size of defects induced due to hydrogen-charging is analyzed.All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications Ltd, www.scientific.net. (Scite.
As its hardness and wear resistance being approximate to that of natural diamond,
polycrystalline diamond (PCD) is a kind of perfect tool material for cutting Si-Al alloy pistons. In
the turning process of Si-Al alloy pistons, the normal wear of PCD tools is a continuous and gradual
process, which mainly is hard grain wear, as well as adhesion wear, diffusion wear, and chemical
wear. The breakages of PCD tools include collapse, crash and flake etc, which occur mainly in
discontinuous turning process. Experimental results and production statistic indicate that about
40~55% of PCD tools failure is breakage in discontinuous turning process of Si-Al alloy pistons.
Reducing impact load is the main method to avoid tool breakage.
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