The objective of this work was to determine the feasibility of FSW for joining DH-36 steel for shipbuilding applications. Welds were produced on 0.18 inch-thick plates of DH-36 steel using tools of W-25%Re with a shoulder diameter of 3/4 inches. The tool was rotated at 400 or 500 rpm and travel speeds of either 8 or 10 ipm were employed. Subsequent to welding the welds were evaluated using optical microscopy, microhardness and tensile testing. No measurable changes in tool dimensions were found after welding suggesting that no appreciable tool wear or deformation occurred. Examination of metallographic samples revealed microstructurally distinct regions including the stir zone, heat-affected zone (HAZ) and base metal. Many of the welds contained small defects near the bottom of the stir zone resulting from incomplete bonding. The base metal rnicrostructure was composed of equiaxed grains of ferrite approximately 15 to 20 p.m in size with pearlite colonies. The rnicrostructure of the base metal also showed evidence of banding. The stir zone rnicrostructure contained grains of acicular ferrite about 5 micrometer in size. No regions of martensite were observed in the stir zone. The HAZ contained regions of partially spherodized pearlite (fuzzy pearlite) but no graincoarsened or grain-refined regions. The banding extended from the base metal into the stir zone. The microhardness of the stir zone averaged approximately 215 VHN, while that of the base metal was about 190 to 195 VHN. Consistent with the lack of martensite, no evidence of hardening was found in the microhardness results. The weld samples showed acceptable strain to failure with yield and tensile strengths exceeding those of the base metal. With one exception, all samples failed through the stir zone owing to the presence of lack-ofbonding defects. These defects can be eliminated with proper tool design. FSW of DH-36 appears feasible, and further work is warranted.
Friction stir welding of DH-36 steel
Reibrührschweißen der Stahlsorte DH-36
2003
7 Seiten, 3 Bilder, 3 Tabellen, 7 Quellen
Aufsatz (Konferenz)
Englisch
SAE Technical Papers | 2007
|Friction stir welding of aluminum alloy to steel
Tema Archiv | 2004
|FRICTION STIR WELDING MACHINE, AND FRICTION STIR WELDING SYSTEMS WITH SUCH MACHINE
Europäisches Patentamt | 2016
|Friction Stir Welding and NASA
NTIS | 2016
|