Radiation-Induced Stress Relaxation of Welded Type 304 Stainless Steel Evaluated by Neutron Diffraction

2008 ◽  
pp. 15-15-17
Author(s):  
M Obata ◽  
JH Root ◽  
Y Ishiyama ◽  
K Nakata ◽  
H Sakamoto ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Stress Relaxation ◽  
Neutron Diffraction ◽  
304 Stainless Steel ◽  
Induced Stress ◽  
Radiation Induced ◽  
Type 304 ◽  
Type 304 Stainless Steel

Hot Cell Pulsed Laser Welding of Neutron Irradiated Type 304 Stainless Steel With a Maximum Damage Dose of 28 DPA

2019 ◽  
Author(s):  
Paula D. Freyer ◽  
Jonathan K. Tatman ◽  
Frank A. Garner ◽  
Greg J. Frederick ◽  
Benjamin J. Sutton
Keyword(s):  
Stainless Steel ◽  
Heat Input ◽  
Welding Process ◽  
Pressure Vessels ◽  
Department Of Energy ◽  
304 Stainless Steel ◽  
Feed Speed ◽  
Radiation Induced ◽  
Type 304 ◽  
Type 304 Stainless Steel

Abstract Radiation-induced degradation of reactor pressure vessels and internals is a concern to the aging nuclear fleet and welding solutions will be required if repair of these irradiated components is deemed necessary. However, the weldability of highly irradiated austenitic materials is significantly diminished due to the presence of irradiation induced helium in the material matrix. Helium-induced weld cracking is a complex phenomenon that is related to the concentration of helium, the heat input from the welding process, and stresses generated during cooling of the weld. During conventional high heat input welding methods such as gas tungsten arc welding, helium bubbles can coalesce and grow on base metal grain boundaries within the heat-affected zone which subsequently causes intergranular cracking. The objective of this work was to obtain weldability data by characterizing welds made on highly activated, neutron irradiated Type 304 stainless steel containing both radiation-induced helium and microstructural damage such as void swelling. All irradiated materials welding was performed inside a Westinghouse hot cell utilizing a pulsed Nd:YAG laser with welds made on three rectangular samples of highly activated Type 304 stainless steel. The rectangular samples were cut and milled in-cell from sections previously obtained from two neutron reflector hex blocks. The hex blocks are U.S. Department of Energy owned material and were irradiated for approximately 13 years in the EBR-II sodium cooled fast reactor from 1982 until 1995. The three samples selected for welding have nominal damage doses of approximately 0.4, 11, and 28 dpa with corresponding estimated helium contents of 0.2, 3 and 8 appm helium, respectively. A number of different weld parameter sets were utilized and included variations of travel speed, wire feed speed and lens-to-work distances. The parameter sets allowed for a range of effective weld heat input levels to be compared. Single pass and multiple pass as well as wire fed and autogenous welds were made. This paper presents the results from post-weld evaluations performed on the three welded irradiated samples, focusing on the reduced tendency for cracks to form adjacent to the weld as a function of weld parameters, lens-to-work distance and helium content.

Creep, Stress Relaxation and Biaxial Ratchetting of Type 304 Stainless Steel After Cyclic Preloading

1994 ◽  
Vol 116 (2) ◽  
pp. 133-141 ◽  
Author(s):  
Hiromasa Ishikawa ◽  
Katsuhiko Sasaki
Keyword(s):  
Stainless Steel ◽  
Stress Relaxation ◽  
Back Stress ◽  
Material Behavior ◽  
Cyclic Plasticity ◽  
304 Stainless Steel ◽  
Cyclic Shear ◽  
Creep Stress ◽  
Type 304 ◽  
Type 304 Stainless Steel

A series of tests for creep, stress relaxation, and biaxial ratchetting of type 304 stainless steel after cyclic preloading were carried out to investigate their interaction. The interesting fact was pointed out that back stress in cyclic plasticity played an important role to describe creep, relaxation, and biaxial ratchetting following cyclic preloading. Then, the test results showed that the material behavior due to creep after cyclic preloading could be represented by the modified Bailey-Norton law with stress levels evaluated from the current center of the yield surface, i.e., back stress which was determined by the hybrid constitutive model for cyclic plasticity proposed by the authors. In addition, biaxial ratchetting of axial strain induced by cyclic shear straining after cyclic preloading was expressed by the shear stress amplitude, the number of cycle and the axial stress level from the current center.

Effect of Prestrain on Stress Corrosion Cracking of Type 304 Stainless Steel by Means of the Stress Relaxation Method

CORROSION ◽  
1979 ◽  
Vol 35 (10) ◽  
pp. 456-460 ◽  
Author(s):  
HIDEHIKO KAMIDE ◽  
HIDEO SUGAWARA
Keyword(s):  
Stainless Steel ◽  
Stress Relaxation ◽  
Stress Corrosion ◽  
Stress Corrosion Cracking ◽  
Annealing Temperature ◽  
Relaxation Method ◽  
304 Stainless Steel ◽  
Deformation Structures ◽  
Type 304 ◽  
Type 304 Stainless Steel

Abstract The relationship between the susceptibility of stress corrosion cracking (SCC) and the amount of deformation structures in Type 304 stainless steel in an H2SO4/NaCI solution system at room temperature was investigated by means of the stress relaxation method. SCC was observed in the prestrained specimens, whereas no cracking occurred in specimens without prestraining. The number of cracks was affected by the amount of deformation structures, which varied according to the annealing temperature after prestraining or according to the prestraining temperature. The results of magnetic measurements on the prestrained specimens as a function of the annealing temperature showed that the cracking region was in good agreement with the range of existence of strain induced α-martensites. Transmission electron microscope observation showed that ε- and α-martensites formed by prestraining at temperatures below 413 K (140 C) dissolved in preference to the austenite matrix. A strain induced martensite in Type 304 stainless steel seems to precede cracking in this system.

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