| 摘要 |
PURPOSE:To obtain a tester which is small in size, is easy to manufacture and is inexpensive by giving prescribed displacements to a test piece, maintaining the same roughly constant and measuring the load applied thereupon. CONSTITUTION:With a loading bar 3 held removed, load is applied upon a ring 1 by using a strain gage 2 and the load of the ring 1 is beforehand calibrated. Prescribed load is applied upon a test piece 5 by means of the bar 3 and nuts 7, and the piece 5 is held in a stress corrosion cracking atmosphere in a tank 8, whereby the test piece is tested. During the course of the test, the load is measured with the gages 2 adhered to the ring 1 and the opening displacements of the test piece 5 are measured periodically or continuously with a clip gage 6. Crack length can be determined by (opening displacement/load) and from the crack length and the load or the opening displacement, the coefft. of stress expansion is determined. Since the ring 1 of sufficiently large toughness is used, the coefft. of stress expansion decreases on progression of the crack and when the value of KICC is attained, the progresses of the crack ceases. |
