コバルトフリー材の耐摩耗性に及ぼす炭化物の分散効果

抄録

In order to reduce radiation exposure in nuclear plants (ABWR), Co-free wear resistant alloys for rollers and pins in FMCRD (Fine Motion Control Rod Drive) were investigated. Wear properties of conventional Ni-base alloy (WPM) for rollers and Fe-base alloy (Fe-Alloy 60) for pins used in control rods were evaluated under a high applied load equivalent to that in the FMCRD.
It was proved that the wear loss of Fe-Alloy 60 (pin) was much larger than that of Co-base alloy under the high load. To improve the wear resistance, modification of Fe-Alloy 60 was carried out by adding V and C, expecting dispersion of primary carbide in the matrix.
Modified Fe-Alloy 60 added V(3mass%) and C(0.75mass%) showed a great improvement of wear loss, the same level as Co-base alloy, in the high load. It was found that the dispersed carbide was Cr carbide containing V, and that the carbide played an effective role of restraining the plastic deformation of wearing surfaces.
The pins of modified Fe-Alloy 60 have enough toughness to impact and good corrosion resistance to in a high temperature water of 288°C.