Low-expansion superalloys are susceptible to weld solidification cracks and heat,affected zone （HAZ）microflssures. To predict solidification cracking, QBasic procedures were developed and solidification reaction se...Low-expansion superalloys are susceptible to weld solidification cracks and heat,affected zone （HAZ）microflssures. To predict solidification cracking, QBasic procedures were developed and solidification reaction sequence, type, and amount of eutectic product were caiculated As manifested, primary solidification is followed by L→（Y＋ NbC） and L → （Y＋ Laves） eutectic reaction sequentially for G H903 and GH907; hence, the terminal eutectic constitue Y/Laves, While for GH909, intsare made up of Y/NbC and Y/only reaction L → （Y ＋ Laves） occurs and more Y/Laves eutectic forms. Therefore, GH909is more sensitive to solidification cracking. To predict HAZ liquation, cracking Visual FORTRAN procedures were developed, and constitutional liquation of NbC was simulated. As shown, solid dissolution of NbC prior to liquation decreases, and initial liquid film increases with the rate of thermal cycle. Higher rate of thermal cycle promotes the melting of the matrix adjacent to the liquid film and postpones the solidification of the at the eutectic n size and peak rifled indirectly by hot ductility tests.展开更多
文摘Low-expansion superalloys are susceptible to weld solidification cracks and heat,affected zone （HAZ）microflssures. To predict solidification cracking, QBasic procedures were developed and solidification reaction sequence, type, and amount of eutectic product were caiculated As manifested, primary solidification is followed by L→（Y＋ NbC） and L → （Y＋ Laves） eutectic reaction sequentially for G H903 and GH907; hence, the terminal eutectic constitue Y/Laves, While for GH909, intsare made up of Y/NbC and Y/only reaction L → （Y ＋ Laves） occurs and more Y/Laves eutectic forms. Therefore, GH909is more sensitive to solidification cracking. To predict HAZ liquation, cracking Visual FORTRAN procedures were developed, and constitutional liquation of NbC was simulated. As shown, solid dissolution of NbC prior to liquation decreases, and initial liquid film increases with the rate of thermal cycle. Higher rate of thermal cycle promotes the melting of the matrix adjacent to the liquid film and postpones the solidification of the at the eutectic n size and peak rifled indirectly by hot ductility tests.
