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Mechanical Properties and Weldability of Turbine Impeller Materials for High Temperature Exhaust Gas Turbocharger 1 000 1 050 246 IN100 The increase in environmental awareness in recent years has led to increased demands for improved fuel economy and the reduction of air pollution generated by automobiles. In light of this, there are increasing needs for the use of turbochargers, particularly with regard to gasoline engines. In order to achieve reduced fuel consumption, exhaust gas temperatures exceed 1 000 C and can reach 1 050 C. This research focuses on turbine impellers, evaluating their mechanical properties at elevated temperatures and their weldability to shaft. It was found that 246-equivalent and IN100-equivalent joints have superior properties as turbine impeller materials with regard to high temperature exhaust gas. 1. 緒言 ( 1 ) CO 2 1 000 1 050 ( 2 ) Ni 713C 713C 713C 246 247 IN100 246 247 IN100 2. 試験方法 第 1 表 SCM435H 第 2 表 HIP HIP 1 185 200 MPa 3 h 713C 43

第 1 表 wt Table 1 Typical chemical composition of superalloy and shaft ( wt% ) wt Ni Cr Mo Fe C Si Mn P S Ti 7 1 3 C 12 14 3.8 5.2 < 2.5 0.08 0.2 < 0.5 < 0.25 < 0.015 0.5 1 2 4 7 8 8.8 0.5 0.8 < 0.25 0.13 0.17 < 0.15 < 0.2 < 0.015 < 0.01 0.9 1.2 2 4 6 8 10 2.25 2.75 < 1 0.13 0.17 < 0.2 < 0.2 < 0.015 1.25 1.75 IN100 8 11 2 4 < 0.3 0.15 0.17 < 0.1 < 0.1 < 0.015 < 0.015 4.5 4.8 SCM435H < 0.25 0.85 1.25 0.15 0.35 0.32 0.39 0.15 0.35 0.55 0.95 < 0.03 < 0.03 wt l Nb Zr B Co W Nb + Ta Ta Hf V 7 1 3 C 5.5 6.5 0.05 0.15 0.005 0.015 < 1 1.8 2.8 2 4 7 5.3 5.7 < 0.1 0.03 0.08 0.01 0.02 9 11 9.5 10.5 2.8 3.3 1.2 1.6 2 4 6 5.25 5.75 0.03 0.08 0.01 0.02 9 11 9 11 1.25 1.75 IN100 5 6 < 0.25 0.03 0.01 13 17 < 0.2 0.7 1.2 SCM435H 1 180 2 h 927 16 h 246 1 220 2 h 870 16 h 247 1 070 4 h 870 12 h IN100 1 055 2 h 870 12 h 850560 8 mm 15 mm 400 900 1 050 第 2 表 Table 2 Superalloy density 247 IN100 3 mm 713C 247 IN100 800 713C 700 R = 0.01 ( g/cm 3 ) 7 1 3 C 7.91 2 4 7 8.54 2 4 6 8.50 IN100 7.75 850 290 MPa 850 400 MPa 1 050 800 850 60 kv 10.5 m 1 m/min ( FE-SEM ) 3. 結果および考察 3. 1 新タービンインペラ候補材の高温強度評価 第 1 図 第 2 表 713C 247 IN100 246 ( MPa g 1 cm 3 ) 150 100 50 713C IN100 247 246 0 300 400 500 600 700 800 900 1 000 1 100 第 1 図 Fig. 1 Temperature dependence of tensile strength of round bar specimens 44

400 700 713C 247 IN100 IN100 800 713C 3 247 IN100 246 850 IN100 247 第 2 図 247 IN100 800 713C 700 815 246 ( 3 ) 247 246 IN100 247 100713C 第 3 図 247 IN100 1 IN100 247 ( 3 ) IN100 247 ( MPa g 1 cm 3 ) 120 110 100 90 80 70 713C *1 IN100 247 246 *2 60 1 000 10 4 10 5 10 6 10 7 10 8 *1 700 *2 815 R = 0.01 第 2 図 800 Fig. 2 xial fatigue properties of specimens cut from T/W and of round bar specimens at 800 ( MPa g 1 cm 3 ) 80 70 60 50 40 30 20 10 246 713C ( 3 ) 1 Larson-Miller C = 20 第 3 図 246 IN100 247 713C 713C IN100 第 2 表 IN100 IN100 247 247 IN100 1 IN100 1 247 1 713C 1 246 1 100 3. 2 合金鋼シャフトとの接合性評価 Ni l Ti l Ti ( 4 ) l Ti IN100 1 000 10 4 10 5 ( h ) 第 3 図 850 Fig. 3 Diagram of stress vs. time to rupture of round bar specimens at 850 第 4 図 713C 247 246 IN100 45

( a ) 713C ( b ) 247 ( c ) 246 ( d ) IN100 1.7 1.7 1.7 1.7 B B B B 2.5 2.3 2.7 2.7 200 µm 200 µm 200 µm 200 µm 第 4 図 713C 247 246 IN100 mm Fig. 4 Microstructures of dissimilar joints between turbine wheels and chromium molybdenum shaft ( unit : mm ) B 1.7 mm 0.5 mm 713C 2.5 mm 247 246 2.7 mm IN100 2.3 mm ( 5 ) 第 5 図 713C 247 IN100 HIP ( MPa ) 1 000 800 600 400 200 0 713C 247 246 IN100 第 5 図 713C 247 246 IN100 Fig. 5 Tensile strength of dissimilar joints between several turbine impellers and chromium molybdenum steel shafts 246 HIP 713C 752 MPa 734 MPa 247 524 MPa 512 MPa 713C 246 805 MPa IN100 833 MPa 720 MPa 713C 第 6 図 713C 246 IN100 247 第 6 図 - ( b ) 第 7 図 713C 247 第 7 図 - ( a ) 713C 第 7 46

( a ) 713C ( b ) 247 500 µm 500 µm ( c ) 246 ( d ) IN100 500 µm 500 µm 第 6 図 713C 247 246 IN100 Fig. 6 Fracture surfaces of dissimilar joints ( a ) ( b ) ( c ) 713C 50 µm 50 µm ( d ) ( e ) ( f ) 247 第 7 図 713C 247 Fig. 7 Fracture surfaces at higher magnification after tensile test 図 - ( b ) - ( c ) 第 7 図 - ( d ) - ( e ) - ( f ) 247 第 7 図 - ( d ) - ( c ) 713C 第 7 図 - ( e ) - ( f ) 47

247 第 8 図 713C 247 713C 50 247 第 6 図 第 7 図 247 713C 247 第 7 図 - ( e ) - ( f ) 247 第 9 図 247 247 Hf Hf g ( 6 ) 第 9 図 247 Fig. 9 Hot tear along with fusion line between 247-equivalent and chromium molybdenum steel joints ( a ) 713C ( b ) 247 200 µm 200 µm 第 8 図 713C 247 Fig. 8 Microstructure of dissimilar joints ruptured by tensile test 48

3 247 IN100 4. 結言 713C IN100 246 IN100 713C 247 246 246 IN100 246 IN100 参考文献 ( 1 ) utomotive Technology Vol. 1 2008 1 pp. 122 123 ( 2 ) IHI 33 4 2005 7 pp. 3 10 ( 3 ) erospace Structural Metals Handbook ( 4 ) W.. Owczararski Process and metallurgical factors in joining superalloys and other high service temperature materials Superalloys Source Book SM ( 1984 ) pp. 369 400 ( 5 ) p. 69 ( 6 ) T. B. Massalski BINRY LLOY PHSE DIGRMS second edition Vol. 2 p. 2 095 49