As a part of design considerations, welded joints of 18 Ni 1700 maraging Steel rocket booster casings are required to have 90% weld efficiency with respect to strength as well as fracture toughness. Achieving 90 % weld efficiency in KIC has been a big challenge, especially with filler wires having matching composition as that of base metal. Reasons for low K IC has been traced to formation of relatively soft reverted austenite pools in the interdendritic regions of weld melt. EPMA has confirmed segregation of Mo and Ti in these regions leading to austenite reversion during aging. Consequently, Mo and Ti were reduced in the new filler wire composition while levels of Co and Al was increased to ensure adequate strength of welds after aging. Welds with modified filler wire was free from reverted austenite, with KIC of 85 Mpa m1/2 at strength level of 1600 Mpa, which translates to over 90% weld efficiency with respect to strength as well as toughness. The paper discusses structure and properties of maraging steel weldmelts vis-a-vis composition of filler wires.
New filler wire for welding 250 grade maraging steels
MS&T, Materials Science and Technology, 2008 ; 1832-1836
2008
5 Seiten, 2 Quellen
Aufsatz (Konferenz)
Englisch
Austenit , Bruchzähigkeit , Casing-Rohr , Drahtelektrode , Elektronenstrahlmikroanalyse , Fülldrahtelektrode , Fülldrahtschweißen , Laserstrahlschweißen , martensitaushärtbarer Stahl , Molybdänzusatz , Nickelstahl , Raketenbau , Schweißverbindung , Spannungsintensitätsfaktor , Teilchenzähler , Titanzusatz , Verschleißfestigkeit
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