Simple test for dissimilar-metal welds
A simplified accelerated test procedure has been developed for testing dissimilar-metal welds between austenitic stainless steels and low-alloy ferritic steels. The failure of these welded joints in operating steam generators of fossil-fired power plants has become an increasing problem for the utility industry. The proposed test is a three-point loading, bent-beam test that uses sheet specimens taken from a dissimilar-metal weldment. Tests were conducted in a simple test fixture where the specimens are loaded with a set-screw. To determine whether the test produces the same type of failure as those produced in a power plant, tests were conducted on specimens taken from a weld between Type 316 stainless steel and 2 1/4 Cr-1 Mo steel plates using Type 309 stainless steel filler metal. The specimens were loaded in the test fixture at room temperature and then thermally cycled between room temperature and 593/sup 0/C (1099/sup 0/F) by placing the test apparatus in a box furnace (thermal cycling during power plant operation plays a major role in the weld failure during service). The specimens were kept in the furnace for 20 to 70 hours (h), cooled to room temperature, and then the cycle was repeated. Metallographic examination of specimens cycled as few as 64 times with a total of 2300 h at 593/sup 0/C revealed that the specimens contained cracks similar to the cracks observed on dissimilar-metal welds cut from steam tubes after long-time elevated-temperature service racks similar to the cracks observed on dissimilar-metal welds cut from steam tubes after longtime elevated-temperature service in a fossil-fired steam generator. All indications are that this simple accelerated test could be used as a screening procedure to compare the relative behavior of ''improved'' welds in future research and development programs.
- Research Organization:
- Oak Ridge National Lab., TN
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6926793
- Journal Information:
- Weld. Res. (Miami); (United States), Journal Name: Weld. Res. (Miami); (United States)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
CHROMIUM-MOLYBDENUM STEELS
WELDING
STAINLESS STEEL-316
STEAM GENERATORS
MATERIALS
WELDED JOINTS
TESTING
FOSSIL-FUEL POWER PLANTS
ALLOYS
BOILERS
CHROMIUM ALLOYS
CHROMIUM STEELS
CHROMIUM-NICKEL STEELS
CORROSION RESISTANT ALLOYS
FABRICATION
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
IRON ALLOYS
IRON BASE ALLOYS
JOINING
JOINTS
MOLYBDENUM ALLOYS
NICKEL ALLOYS
POWER PLANTS
STAINLESS STEELS
STEELS
THERMAL POWER PLANTS
VAPOR GENERATORS
200104* - Fossil-Fueled Power Plants- Components
360101 - Metals & Alloys- Preparation & Fabrication