Tham khảo tài liệu 'volume 07 - powder metal technologies and applications part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Note Heat treatment 1150 C 2100 F 760 C 1400 F 8 h. Source Ref 7 Udimet 720 was originally developed as a wrought turbine blade alloy for industrial turbines. In the cast and wrought form it is being used as a turbine disk alloy. More recently the alloy has been evaluated as a P M material Ref 18 19 . Reportedly P M Udimet 720 has excellent fatigue crack growth resistance and is being strongly considered as a disk material in small to medium gas turbine engines as well as aircraft auxiliary power units. Udimet 720 can be produced by HIP or by extrusion plus isothermal forging. Figure 7 shows a fully machined P M Udimet 720 turbine disk produced by extrusion plus isothermal forging. A comparison of the costs for P M and cast and wrought Udimet 720 disks showed more than 20 cost reduction with the P M process Ref 18 . Tensile properties for P M Udimet 720 are shown in Fig. 8 and the results of fatigue crack growth rate tests of P M and cast and wrought material are shown in Fig. 9. Low-cycle fatigue tests R Kt F 20 cpm at 425 540 and 650 C 800 1000 and 1200 F have shown that the P M Udimet 720 has mean lives that are higher than cast and wrought Udimet 720. Fig. 7 Fully machined P M Udimet 720 turbine disk produced by extrusion plus isothermal forging. Courtesy of Allison Engine Company Fig. 8 Tensile properties of P M Udimet 720 turbine disk produced by extrusion plus isothermal forging heat treatment 1090 C 2000 F two-step age . Source Ref 18 Fig. 9 Fatigue crack growth rates for P M Udimet 720 turbine disk produced by extrusion plus isothermal forging heat treatment 1090 C 2000 F two-step age compared to cast and wrought C W Udimet 720. Source Ref 18 IN-706 is an iron-nickel-base superalloy that is used for very large forged turbine disks in land-based turbine engines for power generation. Cast and wrought processing for these applications includes vacuum induction melting plus electroslag remelting plus vacuum arc remelting to minimize melt-related .
