The crack propagation tests on the fundamental structure under cyclic thermal transients; Results of destructive inspection for surface cracks

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This report shows the experimental results of crack propagation tests using the air-cooled thermal transient test facility (ATTF). These tests were carried out to get the crack growth data on fundamental structures under cyclic thermal transients. The test specimens were made of 304 type austenitic stainless steel. Geometry is cylindrical shape, 1500 mm in height, 130 mm in outer diameter and 30 mm in thickness. And they had semi-elliptical initial slits machined on inner surfaces. The specimen was heated up to 650 C by furnace, then cooled by pressurized air blowing in the specimen for 90 seconds. Cyclic change of temperature gradients in the wall of specimens was loaded by this sequence. The tests were continued till 10,000 cycles at maximum case. Specimens were tested during several years. The specimen No. CPTT-102 with machined two circumferential slits and two semi-elliptical slits was tested up to 10,000 cycles. And the specimen No. CPTT-103 with machined six semi-elliptical slits of different length respectively was tested up to 5,000 cycles. This report concerns to feature of cracks that grew up from semi-elliptical slits on both No. CPTT-102 and No. CPTT-103.