·Table of Contents
·Methods and Instrumentation
HIC and Steel Cleanliness InspectionAuthor:Joachim Staudt, AG der Dillinger Hüttenwerke, D - Dillingen
Co-Author:Ulrich Sauer, Krautkrämer GmbH & Co. oHG, D - Hürth
The makers of pipelines, e.g. more often require "HIC" - resistant steels (HIC = hydrogen induced cracking), including the corresponding test documentation. HIC samples are used to test the resistance of steels against HIC induced cracks. The HIC samples are stored in a saturated hydrogen sulphide solution for a certain time, afterwards these samples are artificially aged in a simulation process.
The destructive metallographic test is today often substituted by a non-destructive ultrasonic immersion test.
The DILLINGER HÜTTE (DH), in co-operation with KRAUTKRÄMER (KK), has taken a new computer controlled ultrasonic immersion test system with automatic evaluation in operation
This test installation is used at the DH for the detection of HICs as well as for the determination of the macroscopic cleanliness of steel samples.
Series of samples are scanned in one course, but each single sample is evaluated individually afterwards.
The samples or HIC testing are 20 - 75 mm wide, max. 100 mm long and up to 60 mm thick. The samples for determine the cleanliness are 400 mm wide, approx. 200 mm long and up to 20 mm thick.
|Fig 1: Block diagram||Fig 2: Definition of HIC-cuts and characteristic values||Fig 3: US- and control-electronics|
|Fig 4: Scan unit||Fig 5: Probe, probe holder with samples||Fig 6: Evaluation PC|
The evaluation is performed by an additional independent evaluation PC, connected by LAN
|600 x 600 mm|
|0,1 mm, adjustable in steps of 0,04 mm|
|Stepper motor control with gear|
For evaluation the following variants can be displayed:
Also the corresponding test protocols are generated automatically.
(Example fig. 9).
|Fig 7: A-scan 0,5 mm FBH||Fig 8: C-Scan of test samples (0.5 mm and 1.0 mm FBH)||Fig 9: C-scan of series of samples||Fig 10 : Test protocol|
Thus the production accompanying quality control is automised, the test results are available earlier than before. Since the raw data is stored, the samples can be evaluated according to different algorithms and specs, without rescanning!
A clear indicator for the real importance of these tests and the necessity to automise them, is the number of samples, which had been tested in the past 3 years:
|HIC samples||samples for cleanliness test|
This great amount of samples can only be managed and documented within the daily operational routine with an automatic test installation like the presented test system.
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