1986 Fiscal Year Final Research Report Summary
The Mottling Appearing on Radiographs of Welds and Castings
Project/Area Number |
60420048
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Research Category |
Grant-in-Aid for General Scientific Research (A)
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Allocation Type | Single-year Grants |
Research Field |
溶接工学
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Research Institution | Nagoya Institute of Technology |
Principal Investigator |
WATANABE Toichi Nagoya Institute of Technology, 工学部, 教授 (60024155)
|
Co-Investigator(Kenkyū-buntansha) |
MIZUKOSHI Hideo Nagoya Institute of Technology, 工学部, 助手 (60166006)
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Project Period (FY) |
1985 – 1986
|
Keywords | Welding / Non-destructive Testing / Austenitic Stainless Steel / Low Carbon Steel / Mottling on Radiograph / Welding Defect / 透過X線検査 |
Research Abstract |
The mottling appearing on radiographs of weldments and castings has been studied. 1. Austenitic stainless steel welds. (1) An increase in the integrated intensity of diffracted X-rays caused by internal strains in the weldments may be a prime cause of the radiographic mottling. (2) The grain boundary soundness of the weldments, however, may be one of the factors that affect the contrast of the mottling. Fully austenitic weldments give a small amount of internal strains because of their unsound grain boundaries, and show a pronounced mottling. Ferrite-containing weldments, however, give intense internal strains because of their sound grain boundaries, and show a less pronounced mottling. (3) A divergence of the diffracted X-rays caused by intense internal strains in neighbouring grains may be one of the reasons for the less pronounced mottling of the ferrite containing weldments. 2. Low carbon steel weldments. (1) The contrast of the mottling is pronounced for specimens consist of coarse austenite grains with well developed widmanstatten structure. (2) Since the acicular ferrites in the well developed widmanstatten structure in a coarse austenite grain are in a preferred orientation, diffracted X-ray beams from such ferrite plates having the same crystal orientation reinforce and, therefore, may result in the mottling. It should also be emphasized that the integrated intensity of diffracted X-rays from such ferrite plates will be increased by internal strains in the ferrite plates that are introduced during cooling after welding. (3) Low carbon steel weldments that show pronounced mottling exhibit reduced ductility because of the coarse cast structure.
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Research Products
(2 results)