Fu Wantang

Resistance of a high nitrogen austenitic steel to cavitation erosion

Abstract The resistance to cavitation erosion (CE) was measured using a rotating disk device for a high-nitrogen CrMn austenitic steel. The damaged morphology and microstructure characteristics in the surface layer exposed to CE were analyzed by the use of SEM and TEM. The results show that the resistance to CE of 18Mn18Cr0.5N (HNS) steel is 3.3 and 2.3 times higher than that of 0Cr13Ni6Mo (CrNi1) and 0Cr16Ni5Mo (CrNi2) steels, respectively, which are in commonly used for hydraulic turbine runners. The excellent resistance to CE of HNS steel is related to its good mechanical properties and the following microstructure changes: strengthening due to changes of dislocation configurations and the formation of substructures during CE, consumption of CE impact energy by the processes of CE-induced mechanical twins or stacking faults etc. as well as the strengthening due to the CE-induced products itself, the strengthening due to the block of strong N(C)Me covalent bond on dislocation motion and the reconfiguration of crystal lattices.

Structural changes after cavitation erosion for a CrMnN stainless steel

Abstract The structural changes after cavitation erosion were investigated by the use of backscattering Mossbauer spectra for a CrMnN dual-phase (metastable austenite and martensite) stainless steel. The atomic configurations around iron atoms in martensite before and after cavitation erosion were analyzed and discussed. Because of cavitation erosion, the weight fraction of α-martensite in the surface layer being exposed to cavitation erosion increases gradually, and a new kind of configuration containing more alloying elements around iron atoms in α-martensite is induced whose hyperfine effective magnetic field value is 23.2 T.

High performance steel plates with micro-laminated layer structure produced by plastic deformation

Abstracts are not published in this journal

Co-deposition of Co-Ni alloys and their microstructure analysis by PoSAP

ion concentration in the depositing baths on the Co content and the microstruc-ture in the corresponding deposit was studied by the position sensitive atom probe （PoSAP）,TEM and X-ray diffraction. The Co-Ni phase diagram shows that, at room temperature,there are two phases in Co-Ni alloys, one is eCo with hcp lattice, the other is αCo of fcc lat-tice. A Co-Ni alloy with a Ni content below 27% consists of single eCo, beyond 36% consistsof single αCo, in between consists of eCo + αCo. The examination results of TEM, SEM andX-ray diffraction indicated that the Co-Ni deposits with average grain size of 70 nm and thick-