Evaluation of material homogeniety as a function of thickness of low-alloy ferritic steel

Technical Report · Wed Nov 01 04:00:00 EST 1989

OSTI ID:7008668

Anderson, T. L.; Lambert, M. A. ^[1]

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1. Texas A and M Univ., College Station, TX (USA). Research Foundation

A series of Charpy and nil-ductility transition temperature (NDTT) tests were performed on 8 in. and 12 in. thick forgings of A508-4A, A508-4B, and A350-LF3 steels. Three different positions in thickness were tested in the 12 in. forgings, while two locations in the forging were analyzed. Chemical analysis and metallographic examination were also performed on each material and in each thickness location. The material toughness tended to be lower in the thicker forgings and in the center of a given forging. Low relative toughness coincided with well tempered microstructures, where equiaxed ferrite grains had begun to form. These grains are coarser than the packet structure that existed at earlier stages of tempering. Low quench rates (associated with thick sections and central regions of a given thickness) apparently accelerated the structural changes during tempering, which led to microstructures with low toughness. The NDTT results were suspect because most arrests occurred in the heat affected zones (HAZs) of the welds rather than in the parent metal. The measured NDTT values were lower than expected, based on published empirical correlations with Charpy energy. This was particularly true for the A508-4A steel. This provided further evidence that the drop weight tests were actually measuring the arrest properties of the HAZ in most cases. The fact that NDTT values were lower than expected is particularly surprising since the anvil test fixture was machined with a deflection stop 25 percent higher than the standard value.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA); Texas A and M Univ., College Station, TX (USA). Research Foundation
• Sponsoring Organization: DOE/DP
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 7008668
• Report Number(s): SAND-89-7096; ON: DE90008069
• Country of Publication: United States
• Language: English

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ALLOYS
CHARPY TEST
CHEMICAL ANALYSIS
CONTAINERS
CRYSTAL STRUCTURE
DESTRUCTIVE TESTING
DIMENSIONS
DOCUMENT TYPES
FABRICATION
FORGING
GRAIN SIZE
HEAT AFFECTED ZONE
IMPACT TESTS
IRON ALLOYS
IRON BASE ALLOYS
JOINTS
LOW ALLOY STEELS
MATERIALS TESTING
MATERIALS WORKING
MECHANICAL PROPERTIES
MECHANICAL TESTS
MICROSTRUCTURE
PROGRESS REPORT
SIZE
STEEL-ASTM-A350
STEEL-ASTM-A508
STEELS
TESTING
THICKNESS
WELDED JOINTS
ZONES