For the commercialization of fast breeder reactors (FBR), it is essential to enhance the economic competitiveness by reduction of total cost by elongation of plant service period. In this point of view, it is important to establish the assessment method of integrity of aged weld joint and repair welding for the components of future long life FBR. In the present study, evolution of microstructure is evaluated for the 304SS-304SS weld joint which was used for 88,000h at 526-545°C in the French proto-typ...
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Influence of FBR plant service and repair welding on microstructure and residual stress of austenitic stainless steel weld joint

In nuclear power plants, surface treatment including the shot peening is carried out after welding for the prevention of stress corrosion cracking. In this research, the authors developed evaluation systems of the persistence of compressive residual stresses due to shot peening based on the Idealized Explicit FEM which can conduct large-scale non-linear structure analyses in realistic computing time. The developed evaluation system was applied to the analysis of the compressive residual stress due to sho...
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Study of behaver to relieve residual stress at the time of the shot peening

残留応力とは、読んで字のごとく、外力を負荷しない状況においても、物体内部に存在し続ける応力のことを言う。この残留応力は、例えば、工業製品の製造工程における、機械加工、塑性加工、接合、組み立てなどに起因して発生し、機械部品の寸法精度や、その疲労強度などに影響することが知られている。時に、疲労破壊を原因とした事故が報道されることがあるが、こういった疲労破壊の多くは、その破壊起点周辺の引張残留応力に起因するものが多い [1]。このように、人命にも関わる重大事故にも繋がりかねない残留応力は、「ものづくり」の分野において重要な力学パラメータの一つであり、残留応力を知ること、そしてそれを制御することは、信頼性の高い製品開発に重要である。しかし、残留応力は直接目に見ることはできないために、どこにどれだけの大きさの残留応力が発生しているかを把握することは難しい。そのため、何らかの方法により、その残留応力を定量化し可視化することが必要になる。 残留応力測定に対するニーズには、ものを壊すことなく非破壊で測定できること、実機そのもの、あるいは実機にできるだけ近い状態で測定できること、数 mm以下の高い空間分解能で応力分布の測定がで...

For the commercialization of fast breeder reactors (FBR), it is essential to enhance the economic competitiveness by reduction of total cost by elongation of plant service period. For this reason, it is needed to establish the aged weld joint integrity assessment method for future FBR compon ents. Additionally, since it is expected to employ the repair weld for aged structural components, it is essential to investigate the effect of repair weld. To investigate the influence of high temperature-long service...
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Basic investigation of aging weld joint and repair weld joint integrity assessmentusing neutron residual stress measurement method

To validate the FEM simulation technique presented in the previous report, we made pipe butt welded joints between base metals of the same material SUS316L and between base metals of the dissimilar materials SUS316L and STPT370. Shot peening (SP) on the outer surface or the inner surface of these welded joints induces high compressive residual stresses on the surface. After heat treatment with the peak temperature of 623 K was applied to the welded joints, they retained high compressive residual stresses ...
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Evaluation of the sustainability of compressive residual stress by introduced a stress improvement method (the second report) ?Residual stress change of welded joint with shot peening by thermal cycle and stress loading.

When the steel structure is built such as nuclear power plant, residual stress occurs in or near the welding joint and it may cause the stress collision cracking(SCC). Therefore, as prediction of SCC, surface treatment such as the shot peening(following SP) is carried out in the weld, but the case analyzed about residual stress reforming by the SP does not exist. So, we developed the analysis method that can predict compressive residual stress relaxation behavior during shot peening by modelling dynami...
英字タイトル:
Evaluation of the sustainability of compressive residual stress by introduced a stress improvement method (the first report) -Development of analysis method of the shot peening using idealized explicit FEM