The Analysis on Causes of Rupture of a HP-Nb High Temperature Alloy Radiant Furnace Tube

2006 ◽  
Author(s):  
Shuanlu Lu ◽  
Pinsheng Zhang ◽  
Changyi Qin ◽  
Xinhu Wang ◽  
Faqian Luo ◽  
...  
Keyword(s):  
High Temperature ◽  
Performance Test ◽  
Mechanical Performance ◽  
High Temperature Creep ◽  
High Temperature Alloy ◽  
Creep Fracture ◽  
Temperature Creep ◽  
Furnace Tube ◽  
Metallographic Inspection ◽  
Fractographic Observation

An explosion accident occurred in a HP-Nb high temperature alloy radiant furnace tube. Twenty one lengths of furnace tubes were broken and cracked during this explosion. This paper investigates the explosion accident. The broken furnace tubes were investigated by fractographic observation and metallographic inspection and with mechanical performance test and analysis to determine the cause of the explosion. The results of the analysis indicated that the failure of the furnace tube was caused by high temperature creep. In order to determine the temperature of the furnace tube failure, some heat simulation tests from 900°C to 1200°C were carried out, the results of which confirmed that the failure of the furnace tube was primarily due to creep fracture because of the high temperature.

Study on the High Temperature Creep Behavior of 30Cr25Ni20 Heat-Resistant Steel

2019 ◽  
Vol 814 ◽  
pp. 157-162
Author(s):  
You Yang ◽  
Xiao Dong Wang ◽  
Wei Feng Tang
Keyword(s):  
High Temperature ◽  
Internal Structure ◽  
Creep Strain ◽  
High Temperature Creep ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Creep Fracture ◽  
Heat Resistant ◽  
Temperature Creep ◽  
Before And After

The high temperature creep test of heat-resisting steel 30Cr25Ni20 for automobile exhaust manifolds was carried out, and the creep strain-time curves at 650°C and 700°C in the different loads were obtained. The effects of different creep temperature and stress on creep life of materials were studied. The microstructure of the fracture after creep was observed by scanning electron microscopy. Microstructures before and after creep at different temperatures were compared by optical microscopy. The results show that the creep fracture life of heat-resistant steel decreases with the increase of stress at the same temperature. The creep fracture life decreases with the increase of temperature at the same stress, too. The fracture of heat-resistant steel shows good high temperature plasticity and a ductile fracture after creep. The fracture dimples become deeper with the increase of stress. At 650°Cand 700°C, the stress exponent is 8.6 and 6, respectively. When the sample was subjected to high temperature creep at 700°C, the precipitates increase obviously and the reticular structure became very large. At this point, the internal structure of the material is destroyed, and the matrix structure becomes unevenly distributed. The failure of the internal structure leads to the dramatic increase of the creep strain, and the failure of the internal structure will be more serious with the deformation of the sample.

A characterization of high temperature creep fracture life for ceramics

1996 ◽  
Vol 15 (22) ◽  
pp. 2002-2007 ◽  
Author(s):  
A. Toshimitsu Yokobori ◽  
T. Yokobori ◽  
K. Yamazaki
Keyword(s):  
High Temperature ◽  
High Temperature Creep ◽  
Creep Fracture ◽  
Temperature Creep

Investigation of Cr34Ni45 Ethylene Cracking Furnace Tube in Service

2013 ◽  
Vol 834-836 ◽  
pp. 390-400
Author(s):  
Ruo Kang Song ◽  
Mai Cang Zhang ◽  
Jian Xing Dong ◽  
Chen Yang Du
Keyword(s):  
High Temperature ◽  
Performance Test ◽  
Mechanical Performance ◽  
Cast Alloy ◽  
Test Methods ◽  
Time Service ◽  
Oxidation Layer ◽  
Furnace Tube ◽  
Property Changes ◽  
Ethylene Cracking Furnace

The structure and mechanical property changes of Cr34Ni45 ethylene cracking furnace tube serviced for different time (as-cast, 1.5 years and 6 years) are systematically investigated by using SEM, EMPA, XRD and mechanics performance test methods. The microstructure of the as-cast alloy consists of austenitic matrix, NbC and M7C3 primary carbides. Eutectic M7C3 transform into M23C6, and the NbC transform into Nb3Ni2Si which is so-called η-phase during service, accompany with precipitation of secondary M23C6. Furthermore, comparing to original uniform microstructure distribution, there are three zones including oxidation layer, carbides depletion zone and carbides-rich zone at the subsurface region of the inner-wall of Cr35Ni45 tubes after long time service. Oxidation behaviors at high temperature consist of external oxidation of chromium and internal oxidation of silicon. The carburizing behavior of Cr35Ni45 tube is mainly caused by the coking on the surface of inner-wall, but carburization of the serviced tubes are both at lesser-degree because of the auto-remediation of outer oxidation layer. High temperature service heavily reduced mechanical performance of the tubes, and fracture mode transform from a mixed mode to a brittle one during service.

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