Failure Analysis of Expansion Bellows Serving in Steam Pipe Network

2013 ◽  
Author(s):  
Yichang Huang ◽  
Xiaoying Tang ◽  
Houde Yu ◽  
Yaozhou Qian ◽  
Ruqing Wu
Keyword(s):  
Stress Raiser ◽  
Pipe Network ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Spider Web ◽  
Type 316L ◽  
Small Cracks ◽  
Steam Pipe ◽  
As Stress ◽  
Type 316L Stainless Steel

The failure of Type 316L stainless steel expansion bellows serving in steam pipe network has been analyzed. The expansion bellows cracked after approximately 4-year service in steam network at 230°C. The caustic stress corrosion cracking (caustic-SCC) resulting from a combined function of caustic concentrating, metal temperature and residual stress was responsible for the failure. Cracking initiated on the inside surface of the bellow at the peak where served as stress raiser by observation of sample taken from failed expansion bellows. The pattern of cracking was shown as a spider web of several small cracks in photomicrographs. The metallographic examination also indicated that cracks were predominantly transgranular. The oxides on the surface of cracks can be confirmed to be caustic NaOH through X-ray diffraction (XRD) examination.

Research on Welding Repair for Tee Joint Crack of Final Superheater Header of 300MW Station Boiler

2012 ◽  
Vol 235 ◽  
pp. 96-100
Author(s):  
Xiao Guang Niu ◽  
Qing Wang ◽  
Xiang Feng Zheng ◽  
Xue Xia Xu ◽  
Hui Fan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Residual Stress ◽  
Main Crack ◽  
Welding Residual Stress ◽  
Fusion Line ◽  
Power Station ◽  
Metallographic Examination ◽  
Small Cracks ◽  
Steam Pipe ◽  
Power Station Boiler

Through methods, such as microscope analysis, metallographic examination, the crack located nearby the fusion line between tee joint and outlet steam pipe of subcritical power station boiler final superheater header is reheat crack (the main crack occurred in the heat affected zone and extended along the fusion line and grain boundary in HAZ. There are many small cracks paralleling with main crack). The base metal material (12Cr1MoV) and excessive welding residual stress are the primary inducement of crack. In repair crack, the measures of reducing residual stress, such as lower welding heat input, reducing thickness of welding layer, hammer blowing, assigning reasonably heat treatment power ,lengthening holding time and so on, were taken. The welding repair succeeded greatly.

Microstructure of Electro-Eroded Cemented Carbide Surfaces

1968 ◽  
Vol 26 ◽  
pp. 284-285
Author(s):  
V. N. Filimonenko ◽  
M. H. Richman ◽  
J. Gurland
Keyword(s):  
Surface Layer ◽  
Cobalt Content ◽  
Cemented Carbides ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Metallographic Examination ◽  
Standard Procedures ◽  
Face Centered ◽  
Diamond Paste ◽  
Plastic Carbon

The high temperatures and pressures that are found in a spark gap during electrical discharging lead to a sharp phase transition and structural transformation in the surface layer of cemented carbides containing WC and cobalt. By means of X-ray diffraction both W2C and a high-temperature monocarbide of tungsten (face-centered cubic) were detected after electro-erosion. The W2C forms as a result of the peritectic reaction, WC → W2C+C. The existence and amount of the phases depend on both the energy of the electro-spark discharge and the cobalt content. In the case of a low-energy discharge (i.e. C=0.01μF, V = 300v), WC(f.c.c.) is generally formed in the surface layer. However, at high energies, (e.g. C=30μF, V = 300v), W2C is formed at the surface in preference to the monocarbide. The phase transformations in the surface layer are retarded by the presence of larger percentages of cobalt.Metallographic examination of the electro-eroded surfaces of cemented carbides was carried out on samples with 5-30% cobalt content. The specimens were first metallographically polished using diamond paste and standard procedures and then subjected to various electrical discharges on a Servomet spark machining device. The samples were then repolished and etched in a 3% NH4OH electrolyte at -0.5 amp/cm2. Two stage plastic-carbon replicas were then made and shadowed with chromium at 27°.

BIODUR 316LS

Alloy Digest ◽  
1995 ◽  
Vol 44 (6) ◽  
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Tensile Properties ◽  
316L Stainless Steel ◽  
Heat Treating ◽  
Vacuum Arc ◽  
Improve Corrosion Resistance ◽  
Type 316L ◽  
Type 316L Stainless Steel

Abstract BioDur 316LS stainless steel is a modified version of Type 316L stainless steel to improve corrosion resistance for surgical implant applications. The alloy is vacuum arc remelted. This datasheet provides information on composition, physical properties, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-596. Producer or source: Carpenter.

ENDURAMET 316LN

Alloy Digest ◽  
2015 ◽  
Vol 64 (7) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
316L Stainless Steel ◽  
Heat Treating ◽  
Type 316L ◽  
Technology Corporation ◽  
Carpenter Technology Corporation ◽  
Type 316L Stainless Steel

Abstract EnduraMet 316LN stainless is a nitrogen strengthened version of Type 316L stainless steel. This datasheet provides information on composition, physical properties, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-1219. Producer or source: Carpenter Technology Corporation.

scholarly journals Pitting Corrosion of Type 316L Stainless Steel Elaborated by the Selective Laser Melting Method: Influence of Microstructure

2021 ◽  
Author(s):  
V. Vignal ◽  
C. Voltz ◽  
S. Thiébaut ◽  
M. Demésy ◽  
O. Heintz ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
316L Stainless Steel ◽  
Electrochemical Impedance ◽  
Chemical Properties ◽  
Passive Films ◽  
First Order ◽  
Average Grain Size ◽  
Type 316L ◽  
Pure Matrix ◽  
Type 316L Stainless Steel

AbstractThe microstructure of two sets of 316L alloys (SLM and wrought structure) is determined using SPECTROMAXx stationary metal analyzer, FE-SEM/EDS and XRD. The physical–chemical properties of the passive films are also investigated by means of XPS, Auger after sputtering and electrochemical impedance spectroscopy measurements. Differences and similarities between the two sets of alloys are then identified. The corrosion behavior of alloys is investigated in NaCl solution at the macro- and microscale (microcapillary technique). It was found that the inclusion/particles cleanliness is the first-order parameter explaining differences between 316L(WS) and 316L(SLM). In the absence of particles (pure matrix), the two sets of alloys have the same corrosion behavior. Residual stresses, the average grain size, the PREN and the passive films properties are of second order.

Are type 316L stainless steel coin cells stable in nonaqueous carbonate solutions containing NaPF6 or KPF6 salt?

2019 ◽  
Vol 7 (46) ◽  
pp. 26250-26260 ◽  
Author(s):  
Hee Jae Kim ◽  
Hitoshi Yashiro ◽  
Hyungsub Kim ◽  
Seoungsu Lee ◽  
Seung-Taek Myung
Keyword(s):  
Stainless Steel ◽  
316L Stainless Steel ◽  
Carbonate Solutions ◽  
Type 316L ◽  
P Type ◽  
Type 316L Stainless Steel

Type 316L SS is stable in NaPF6 electrolytes, while Fe2+ is dissolved from the type 316L SS in KPF6 electrolytes.

Effect of the Neodymium Content on Mechanical Properties of the Electro-Brush Plated Nano-Al2O3/Ni Composite Coating

2012 ◽  
Vol 525-526 ◽  
pp. 277-280
Author(s):  
Guo Jin ◽  
Xiu Fang Cui ◽  
Er Bao Liu ◽  
Qing Fen Li
Keyword(s):  
Mechanical Properties ◽  
Rare Earth ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Composite Coating ◽  
Nanoindentation Test ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Cracks ◽  
Scanning Electron

The effect of the neodymium content on mechanical properties of the electro-brush plated nanoAl2O3/Ni composite coating was investigated in this paper. The microstructure and phase structure were studied with scanning electron microscope (SEM) and X-ray diffraction (XRD). The hardness and abrasion properties of several coatings with different neodymium content were studied by nanoindentation test and friction / wear experiment. Results show that the coatings are much finer and more compact when the neodymium was added, and the hardness and abrasion property of the coatings with neodymium were improved obviously. Besides, the small cracks conduced by the upgrowth stress in the coatings were ameliorated when the rare earth neodymium was added. The improvement mechanism was further discussed.

Effect of Bubble Inclusions on the Mechanical Properties of Cast Poly-Methyl Metacrylate

1972 ◽  
Vol 94 (4) ◽  
pp. 847-852 ◽  
Author(s):  
J. D. Stachiw
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Loading Condition ◽  
Stress Raiser ◽  
Compressive Yield Strength ◽  
Compressive Test ◽  
Acrylic Plastic ◽  
Methyl Metacrylate ◽  
As Stress ◽  
Stress Raisers

Bubble inclusions present in cast acrylic plastic generally degrade the mechanical properties of the material. To evaluate the effect of bubbles on the mechanical strength of acrylic plastic, 120 tensile and compressive test specimens were machined from massive acrylic castings with bubble inclusions. The specimens were tested under uniaxial loading condition and effect of bubbles on tensile and compressive strength noted. The stress raiser effect of bubbles caused the tensile specimens to fail at stresses 7 to 30 percent lower than observed in specimens without bubbles. The compressive yield strength was not affected by bubbles. However, here the bubbles served as stress raisers also and caused cracks to initiate at the bubble surfaces when the yield strength of acrylic plastic was reached.

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