Fracture Morphology of 13% Chromium Steam Turbine Blading Steel

2008 ◽  
pp. 334-334-16
Author(s):  
SK Bhambri
Keyword(s):  
Steam Turbine ◽  
Fracture Morphology ◽  
Turbine Blading

High Temperature Rupture, Fatigue, and Damping Properties of AISI Designation 616 (Type 422 Stainless) Steel

1965 ◽  
Vol 87 (2) ◽  
pp. 325-332 ◽  
Author(s):  
R. G. Matters ◽  
A. A. Blatherwick
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Steam Turbine ◽  
Stress Rupture ◽  
Fatigue Tests ◽  
Damping Properties ◽  
Temperature Range ◽  
Stress Ratios ◽  
Mean Stresses ◽  
Turbine Blading

This paper covers the high temperature rupture, fatigue, and damping properties of AISI Designation 616 (Type 422) steel conforming substantially to the requirements of ASTM specification A437 grade B4C. This material has been extensively used for boiling and for steam turbine blading for service in the temperature range of 850 to 1000 F. The results of stress rupture and fatigue tests of smooth and notched bars at 800, 950, and 1050 F are presented. Stress rupture tests extend to 2000 hr or more and fatigue tests generally extend to 2 × 107 cycles or about 100 hr. The fatigue tests were performed in a direct stress machine at stress ratios A = infinity, 2.5, and 1.0. Vibration decay damping tests with various mean stresses were performed at 75, 800, 950, and 1050 F.

CRUCIBLE 403

Alloy Digest ◽  
1981 ◽  
Vol 30 (12) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Steam Turbine ◽  
Tensile Properties ◽  
Heat Treating ◽  
Temperature Performance ◽  
Specialty Metals ◽  
Turbine Blading

Abstract CRUCIBLE 403 is a hardenable steel containing 11.50-13.00% chromium. Its composition and mill processing are controlled carefully to produce a product capable of meeting the severe requirements of steam turbine blading and other high-requirement uses. Crucible 403 is magnetic at all times. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness, creep, and fatigue. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-398. Producer or source: Crucible Specialty Metals Division, Colt Industries.

Long Arc Shrouding—A Reliability Improvement for Untuned Steam Turbine Blading

1981 ◽  
Vol 103 (3) ◽  
pp. 522-527 ◽  
Author(s):  
R. J. Ortolano ◽  
J. A. La Rosa ◽  
W. P. Welch
Keyword(s):  
Steam Turbine ◽  
Arc Length ◽  
Variable Speed ◽  
Butt Welding ◽  
Reliability Improvement ◽  
Fatigue Failures ◽  
Short Arc ◽  
Turbine Blading ◽  
Turbine Exhaust

An approach to the design and modification of untuned variable speed steam turbine exhaust blading has been found to be highly successful in eliminating fatigue failures due to the first tangential in-phase mode resonance. The approach consists of butt-welding the shrouds on the short arc blade groups to form a substantially longer arc length. The result is a significant reduction in vibratory stress at resonant speeds. Because of the ease with which the approach can be implemented in the field, backfitting is highly attractive to turbine operators. Availability benefits to the marine, utility, petrochemical, refining, industrial and commercial fields are anticipated.

Studies of nucleating and wet steam flows in two-dimensional cascades

2004 ◽  
Vol 218 (8) ◽  
pp. 843-858 ◽  
Author(s):  
H Mashmoushy ◽  
M R Mahpeykar ◽  
F Bakhtar
Keyword(s):  
Liquid Phase ◽  
Steam Turbine ◽  
Review Article ◽  
Two Dimensional ◽  
Wet Steam ◽  
Blow Down ◽  
Turbine Blading

Many of the problems resulting from the formation and behaviour of the liquid phase in steam turbine blading can be more easily investigated in two-dimensional cascades. To reproduce turbine nucleating and wet steam conditions realistically requires a supply of supercooled steam. The paper is a review article, giving the features of a blow-down cascade tunnel constructed for the purpose and summarizes the results reported. Results obtained in steady supersonic tunnels are also discussed.

Eddy Current Damping: A Concept Study for Steam Turbine Blading

2009 ◽  
Author(s):  
Jacob Laborenz ◽  
Christian Siewert ◽  
Lars Panning ◽  
Jo¨rg Wallaschek ◽  
Christoph Gerber ◽  
...  
Keyword(s):  
Steam Turbine ◽  
Eddy Current ◽  
Theoretical Models ◽  
Forced Response ◽  
Resonance Frequencies ◽  
Different Types ◽  
Stationary Test ◽  
Eddy Current Damping ◽  
Fatigue Failures ◽  
Turbine Blading

In gas and steam turbine applications a common approach to prevent the blades from high cycle fatigue failures due to high vibration amplitudes is the usage of friction damping elements. Besides the intended amplitude reduction this procedure also features some possibly unwanted side effects like a shift in resonance frequencies due to stiffening effects caused by the contact. Thus, as an alternative an eddy current based non-contacting damping concept for the application in turbo machinery is investigated. In this paper two different types of eddy current dampers are considered. Theoretical models for both are established by applying electromagnetic-mechanical theory. The theoretical models are compared to forced response measurements that are performed at a stationary test rig.

Multiharmonic Forced Response Analysis of a Turbine Blading Coupled by Nonlinear Contact Forces

2009 ◽  
Author(s):  
Christian Siewert ◽  
Lars Panning ◽  
Jo¨rg Wallaschek ◽  
Christoph Richter
Keyword(s):  
Frequency Domain ◽  
Steam Turbine ◽  
Equations Of Motion ◽  
Forced Vibrations ◽  
Forced Response ◽  
Contact Forces ◽  
Dynamic Loads ◽  
Turbine Stage ◽  
Nonlinear Equations Of Motion ◽  
Turbine Blading

The rotor blades of a low pressure (LP) steam turbine stage are subjected to high static and dynamic loads during operation. The static loads are mainly due to the centrifugal force and thermal strains, whereas the dynamic loads are caused by fluctuating gas forces resulting in forced vibrations of the blades. The forced vibrations can lead to high cycle fatigue (HCF) failures causing substantial damage and high maintenance effort. Thus, one of the main tasks in the design of LP steam turbine blading is the vibration amplitude reduction in order to avoid high dynamic stresses that could damage the blading. The vibration amplitudes of the blades in a LP steam turbine stage can be reduced significantly to a reasonable amount if adjacent blades are coupled by shroud contacts that reinforce the blading, see Fig. 1. Furthermore, in the case of blade vibrations, relative displacements between neighboring blades occur in the contacts and friction forces are generated that provide additional damping to the structure due to the energy dissipation caused by micro- and macroslip effects. Therefore, the coupling of the blades increases the overall mechanical damping. A three-dimensional structural dynamics model including an appropriate spatial contact model is necessary to predict the contact forces generated by the shroud contacts and to describe the vibrational behavior of the blading with sufficient accuracy. To compute the nonlinear forced vibrations of the coupled blading, the nonlinear equations of motion are solved in the frequency domain owing to the high computational efficiency of this approach. The transformation of the nonlinear equations of motion into the frequency domain can be carried out by representing the steady-state displacement in terms of its harmonic components. After that transformation, the nonlinear forced response is computed as a function of the excitation frequency in the frequency domain.

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