Fracture Analysis on a Cylindrical Shell Section of the Low-Pressure Absorption Tower
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CASE HISTORY—PEER-REVIEWED
Fracture Analysis on a Cylindrical Shell Section of the Low-Pressure Absorption Tower Gang Ma Æ Xiang Ling Æ Lijing Zhang Æ Xiaoguang Yu
Submitted: 1 September 2008 / in revised form: 26 February 2009 / Published online: 31 March 2009 ASM International 2009
Abstract Cracking of a cylindrical shell section from an absorption tower occurred during the hydraulic pressure testing. In order to find out the cause of failure, the cracked cylindrical shell section was inspected and destructively analyzed. Optical microscopy was performed to evaluate the basic microstructure of the material used to fabricate the cylinder and the effect of welding on the microstructure. The fracture surface was examined in a scanning electron microscope, and the effects of the heat treatment temperature on the structure and properties of 410S/16MnR explosively clad plate were investigated. Detailed metallographic studies indicated that bainite existed in the base layer of the explosively welded material. The weld-induced residual stress in the crack origin was investigated by a three-dimensional (3D) finite element model. The numerical result was consistent with the fracture analysis supporting the conclusion that cracking was caused by the poor mechanical properties of the explosively clad plate and that the poor properties were induced by improper heat treatment after explosive welding. The welding residual stresses also contributed to the failure process. Keywords Fracture analysis Bainite Heat treatment Brittle fracture
G. Ma X. Ling (&) L. Zhang X. Yu School of Mechanical and Power Engineering, Nanjing University of Technology, 5 Xin Mo Fan Road, Nanjing, Jiangsu 210009, China e-mail: [email protected] G. Ma e-mail: [email protected]
Introduction This study describes the analysis and investigation of the cause of cracking in a cylindrical shell section made of 410S/16MnR explosively clad plates. The 16MnR steel is a member of a low-alloy steel family that is widely used to fabricate storage tanks for liquefied petroleum gas (LPG) [1, 2]. The stainless steel cladding on the 410S/16MnR explosively clad plates are applied to enhance the stresscorrosion cracking resistance in the absorption tower. After the manufacture process, hydraulic pressure testing was carried out to ensure the operational performance of the absorption tower. The testing parameters included a pressure of approximately 1.8 MPa and a water temperature of about 11 C. The diameter of the absorption tower was 2.8 m. The thicknesses of 410S and 16MnR were 3 and 22 mm, respectively. The hydraulic shell cracked during the hydraulic test. Detailed metallurgical investigations and fractographic observations on the cracked shell section were conducted. Additionally, different heat treatment techniques were used to analyze the effect of temperature on the structure and properties of the 410S/16MnR explosively clad plate. A three-dimensional (3D) finite element model was used to simulate the welding process and to predict the distribution
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