Material Factors Analysis of the Cracking in 0Cr12Mn5Ni4Mo3Al Stainless Steel Pipe Sleeve on Aircraft Flare-Less Pipe Joints

2011 ◽  
Vol 291-294 ◽  
pp. 1091-1094 ◽  
Author(s):  
Fu Guo Li ◽  
Feng Mei Xue ◽  
Wen Jun Yu ◽  
Jian Fei Li
Keyword(s):  
Stainless Steel ◽  
Steel Pipe ◽  
Chemical Compositions ◽  
Working Process ◽  
Equivalent Ratio ◽  
Fracture Failure ◽  
Factors Analysis ◽  
Δ Ferrite ◽  
Stainless Steel Pipe ◽  
Pipe Joints

It is shown that the discreteness of the chemical compositions of 0Cr12Mn5Ni4Mo3Al steel is large and the range of the Cr/Ni equivalent ratio is wide, which has big impact on the content and morphology of ferrite and easy to occur cracking phenomenon when bearing, based on the chemical compositions analysis of pipe sleeve on aircraft flare-less pipe joints. It can be found that the chemical compositions of cracked pipe sleeve are almost meeting the requirements, but the Cr/Ni equivalent ratio is on the high side. So it can be concluded that the fracture failure of pipe sleeve is closely related to the content, shape and distribution of δ-ferrite. Thus, the available solution of the cracking in 0Cr12Mn5Ni4Mo3Al stainless steel pipe sleeve is to reduce the Cr/Ni equivalent ratio within the permissive of nominal chemical compositions and adjust the hot working process to form the reasonable morphology and distribution of δ-ferrite.

Fracture Analysis of Pipe Sleeve on Extrusion Flare-Less Pipe Joints for Aircraft Hydraulic Pipe

2011 ◽  
Vol 291-294 ◽  
pp. 1087-1090 ◽  
Author(s):  
Feng Mei Xue ◽  
Fu Guo Li ◽  
Jiang Li ◽  
Wen Jun Yu ◽  
Jian Fei Li
Keyword(s):  
Stainless Steel ◽  
Shear Stress ◽  
Stress Concentration ◽  
High Strength ◽  
Fracture Analysis ◽  
Forming Process ◽  
Fracture Failure ◽  
Δ Ferrite ◽  
Pipe Joints ◽  
Bearing Behavior

The forming process of aircraft hydraulic pipe joints is investigated through experiments and analyses to solve the cracking problem of pipe sleeve on extrusion flare-less pipe joints. It can be concluded that the internal cause of the fracture failure is connected with the content, shape and distribution of δ-ferrite in 0Cr12Mn5Ni4Mo3Al high strength stainless steel, and the external cause is associated with the bearing behavior in the extrusion-bulging process of pipe sleeve. The crack is formed in the criss-crossing section of δ-ferrite on the function of shear stress in the stress concentration position, which belongs to ductile deformed crack. It eventually induces the intergranular fracture of pipe sleeve along the long axis with the expanding of subsequent crack.

An Experimental and Numerical Methodology to Investigate Crack Growth in a 304L Austenitic Stainless Steel Pipe Under Thermal Fatigue

2010 ◽  
Author(s):  
Pauline Bouin ◽  
Antoine Fissolo ◽  
Ce´dric Gourdin
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Crack Growth ◽  
Thermal Fatigue ◽  
Thermal Loading ◽  
Steel Pipe ◽  
Design Stage ◽  
Inner Surface ◽  
Stainless Steel Pipe

This paper covers work carried out by the French Atomic Energy Commission (CEA) to investigate on mechanisms leading to cracking of piping as a result of thermal loading existing in flow mixing zones. The main purpose of this work is to analyse, with a new experiment and its numerical interpretation, and to understand the mechanism of propagation of cracks in such components. To address this issue, a new specimen has been developed on the basis of the Fat3D experiment. This thermal fatigue test consists in heating a 304L steel pre-cracked tube while cyclically injecting ambient water onto its inner surface. The tube is regularly removed from the furnace for a crack characterisation. Finally, the crack growth is evaluated from the crack length differences between two stops. In parallel, a finite element analysis is developed using the finite element Cast3M code. A pipe with a semi-elliptical crack on its inner surface is modelled. A cyclic thermal loading is imposed on the tube. This loading is in agreement with experimental data. The crack propagates through the thickness. A prediction of the velocity of the crack is finally assessed using a Paris’ law type criteria. Finally, this combined experimental and numerical work on 304L austenitic stainless steel pipes will enable to improve existing methods to accurately predict the crack growth under cyclic thermal loadings in austenitic stainless steel pipe at the design stage.

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