Manufacturing Experience in an Advanced 9%CrMoCoVNbNB Alloy for Ultra-Supercritical Steam Turbine Rotor Forgings and Castings

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Rod Vanstone ◽  
Ian Chilton ◽  
Pawel Jaworski
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Creep Strength ◽  
Stainless Steels ◽  
First Generation ◽  
Turbine Rotor ◽  
Steam Turbines ◽  
Martensitic Stainless Steels ◽  
Operating Temperatures ◽  
New Generation

Advanced 9–12%Cr martensitic stainless steels to enable extension of steam turbine operating temperatures beyond 565 °C have been under development since the 1980s. Steam turbines with operating temperatures approaching 600 °C based on the first generation of these improved alloys, which exploited optimized levels of Mo, W, V, Nb, and N, entered service in the 1990s. Around the same time, a second generation of advanced alloys was developed incorporating additions of Co and B to further enhance creep strength. These alloys have recently been exploited to enable steam turbines with operating temperatures of up to 620 °C, and this new generation of steam turbines is now beginning to enter service. This paper describes the background to the development of these alloys and the experience gained in their application to the manufacture of high temperature rotor forgings and castings.

Manufacturing Experience in an Advanced 9%CrMoCoVNbNB Alloy for USC Steam Turbine Rotor Forgings and Castings

2012 ◽  
Author(s):  
Rod Vanstone ◽  
Ian Chilton ◽  
Pawel Jaworski
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Creep Strength ◽  
Stainless Steels ◽  
First Generation ◽  
Turbine Rotor ◽  
Steam Turbines ◽  
Martensitic Stainless Steels ◽  
Operating Temperatures ◽  
New Generation

Advanced 9–12%Cr martensitic stainless steels to enable extension of steam turbine operating temperatures beyond 565°C have been under development since the 1980s. Steam turbines with operating temperatures approaching 600°C based on the first generation of these improved alloys, which exploited optimised levels of Mo, W, V, Nb and N, entered service in the 1990s. Around the same time a second generation of advanced alloys was developed incorporating additions of Co and B to further enhance creep strength. These alloys have recently been exploited to enable steam turbines with operating temperatures of up to 620°C and this new generation of steam turbines is now beginning to enter service. This paper describes the background to the development of these alloys and the experience gained in their application to the manufacture of high temperature rotor forgings and castings.

Developing New Cast Austenitic Stainless Steels With Improved High-Temperature Creep Resistance

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Neal D. Evans ◽  
Michael J. Pollard
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Creep Strength ◽  
Stainless Steels ◽  
Creep Resistance ◽  
Austenitic Stainless Steels ◽  
Creep Rupture ◽  
Particulate Filter ◽  
Alloy Development ◽  
Wide Range

Oak Ridge National Laboratory and Caterpillar (CAT) have recently developed a new cast austenitic stainless steel, CF8C-Plus, for a wide range of high-temperature applications, including diesel exhaust components and turbine casings. The creep-rupture life of the new CF8C-Plus is over ten times greater than that of the standard cast CF8C stainless steel, and the creep-rupture strength is about 50–70% greater. Another variant, CF8C-Plus Cu/W, has been developed with even more creep strength at 750–850°C. The creep strength of these new cast austenitic stainless steels is close to that of wrought Ni-based superalloys such as 617. CF8C-Plus steel was developed in about 1.5 years using an “engineered microstructure” alloy development approach, which produces creep resistance based on the formation of stable nanocarbides (NbC), and resistance to the formation of deleterious intermetallics (sigma, Laves) during aging or service. The first commercial trial heats (227.5 kg or 500 lb) of CF8C-Plus steel were produced in 2002, and to date, over 27,215 kg (300 tons) have been produced, including various commercial component trials, but mainly for the commercial production of the Caterpillar regeneration system (CRS). The CRS application is a burner housing for the on-highway heavy-duty diesel engines that begins the process to burn-off particulates trapped in the ceramic diesel particulate filter (DPF). The CRS/DPF technology was required to meet the new more stringent emissions regulations in January, 2007, and subjects the CRS to frequent and severe thermal cycling. To date, all CF8C-Plus steel CRS units have performed successfully. The status of testing for other commercial applications of CF8C-Plus steel is also summarized.

Influence of Creep on Low-Cycle Fatigue Life Assessment of Ultra-Supercritical Steam Turbine Rotor

2014 ◽  
Author(s):  
W. Z. Wang ◽  
J. H. Zhang ◽  
H. F. Liu ◽  
Y. Z. Liu
Keyword(s):  
High Temperature ◽  
Steam Turbine ◽  
Fatigue Damage ◽  
Low Cycle Fatigue ◽  
Turbine Rotor ◽  
High Temperature Creep ◽  
Cycle Fatigue ◽  
Term Operation ◽  
Start Up

Linear damage method is widely used to calculate low-cycle fatigue damage of turbine rotor in the long-term operation without fully considering the interaction between creep and low cycle fatigue. However, with the increase of steam turbine pressure and temperature, the influence of high-temperature creep on the strain distribution of turbine rotor becomes significant. Accordingly, the strain for each start-up or shut-down process is different. In the present study, the stress and strain during 21 iterations of continuous start-up, running and shut-down processes was numerically investigated by using the finite element analysis. The influence of high-temperature creep on low cycle fatigue was analyzed in terms of equivalent strain, Mises stress and low cycle fatigue damage. The results demonstrated that the life consumption of turbine rotor due to low cycle fatigue in the long-term operation of startup, running and shutdown should be determined from the full-time coverage of the load of turbine rotor.

scholarly journals Flutter Analysis of a Transonic Steam Turbine Blade with Frequency and Time-Domain Solvers

2019 ◽  
Vol 4 (2) ◽  
pp. 15
Author(s):  
Christian Frey ◽  
Graham Ashcroft ◽  
Hans-Peter Kersken ◽  
Daniel Schlüß
Keyword(s):  
Steam Turbine ◽  
Time Domain ◽  
Turbine Rotor ◽  
Test Case ◽  
Nonlinear Frequency ◽  
Steam Turbines ◽  
Bending Mode ◽  
Flutter Analysis ◽  
Steam Turbine Blade ◽  
Time Marching

The aim of this study was to assess the capabilities of different simulation approaches to predict the flutter stability of a steam turbine rotor. The focus here was on linear and nonlinear frequency domain solvers in combination with the energy method, which is widely used for the prediction of flutter onset. Whereas a GMRES solver was used for the linear problem, the nonlinear methods employed a time-marching procedure. The solvers were applied to the flutter analysis of the first rotor bending mode of the open Durham Steam Turbine test case. This test case is representative of the last stage of modern industrial steam turbines. We compared our results to those published by other researchers in terms of aerodynamic damping and local work per cycle coefficients. Time-domain, harmonic balance, and time-linearised methods were compared to each other in terms of CPU efficiency and accuracy.

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