scholarly journals High Temperature Fatigue of Aged Heavy Section Austenitic Stainless Steels

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 84
Author(s):  
Hugo Wärner ◽  
Guocai Chai ◽  
Johan Moverare ◽  
Mattias Calmunger
Keyword(s):  
High Temperature ◽  
Reference Material ◽  
Structural Stability ◽  
Stainless Steels ◽  
Power Plants ◽  
Electron Backscatter Diffraction ◽  
Niobium Carbide ◽  
Austenitic Stainless Steels ◽  
Dislocation Motion ◽  
Heavy Section

This work investigates two austenitic stainless steels, Sanicro 25 which is a candidate for high temperature heavy section components of future power plants and Esshete 1250 which is used as a reference material. The alloys were subjected to out-of-phase (OP) thermomechanical fatigue (TMF) testing under strain-control in the temperature range of 100 ∘C to 650 ∘C. Both unaged and aged (650 ∘C, 3000 h) TMF specimens were tested to simulate service degradation resulting from long-term usage. The scanning electron microscopy methods electron backscatter diffraction (EBSD) and energy dispersive spectroscopy (EDS) were used to analyse and discuss active failure and deformation mechanisms. The Sanicro 25 results show that the aged specimens suffered increased plastic straining and shorter TMF-life compared to the unaged specimens. The difference in TMF-life of the two test conditions was attributed to an accelerated microstructural evolution that provided decreased the effectiveness for impeding dislocation motion. Ageing did not affect the OP-TMF life of the reference material, Esshete 1250. However, the structural stability and its resistance for cyclic deformation was greatly reduced due to coarsening and cracking of the strengthening niobium carbide precipitates. Sanicro 25 showed the higher structural stability during OP-TMF testing compare with the reference material.

Properties and Experience of High Cr Austenitic Stainless Steel for Boiler Tubes

2007 ◽  
Author(s):  
Yusuke Minami ◽  
Toshihiko Fukui
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Stainless Steels ◽  
Power Plants ◽  
Rupture Strength ◽  
Thermal Power ◽  
Austenitic Stainless Steels ◽  
Environmental Resistance ◽  
Higher Temperature

Recent boilers for thermal power generation are designed for higher temperature and pressure than in the past, and substantial efforts are being made worldwide to establish technology for ultra super critical power plants. Such boilers will require the use of steels having higher strength and better corrosion resistance than conventional 18-8 austenitic stainless steels. High chromium austenitic stainless steel (22Cr-15Ni-Nb-N) has been developed as a candidate material, and creep rupture strength is more than 50% higher than ASME SA-213 Grade TP347H at 700°C. The hot corrosion and steam oxidation resistance of this steel are also superior to 18-8 stainless steels due to higher Cr content. Thirteen years practical service as superheater tubing in a power plant characterized by high pressure (35MPa) and high temperature (615&°C) has revealed that the mechanical properties and environmental resistance of this steel are sufficient for high temperature boiler tube applications.

Long Term High-Temperature Environmental Effect on Impact Toughness in Austenitic Alloys

2014 ◽  
Vol 627 ◽  
pp. 205-208
Author(s):  
Mattias Calmunger ◽  
Guo Cai Chai ◽  
Sten Johansson ◽  
Johan Moverare
Keyword(s):  
High Temperature ◽  
Impact Toughness ◽  
Stainless Steels ◽  
Power Plants ◽  
Austenitic Stainless Steels ◽  
Alloy 617 ◽  
Temperature Environment ◽  
The Impact ◽  
High Temperature Environment

Structural integrity is crucial for the safety of power plants with higher efficiency to meet the increasing global energy consumption. High-temperature environment will demand not only improved high-temperature corrosion resistance but also a maintained sufficient toughness. This study investigates how long term high-temperature environment influence the impact toughness of two austenitic stainless steels (AISI 304 and Sandvik SanicroTM 28) and one nickel-bas alloy (Alloy 617). Alloy 617 has shown increasing impact toughness with both increasing temperature and time, up to 700°C and 3 000 hours, while the two austenitic stainless steels have shown the opposite for the same conditions. At 10 000 hours the impact toughness of Alloy 617 has decreased but the alloy still possess great toughness. Both austenitic stainless steels show embrittlement due to brittle σ-phase and Alloy 617 seems to gain good impact toughness performance from small evenly distributed precipitates.

ALLOY 0Cr25Ni6Mo3CuN

Alloy Digest ◽  
1998 ◽  
Vol 47 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Stainless Steel ◽  
Corrosion Resistance ◽  
High Temperature ◽  
Physical Properties ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Temperature Performance ◽  
Steel Research ◽  
Oil Refinement

Abstract ALLOY 0Cr25Ni6Mo3CuN is one of four grades of duplex stainless steel that were developed and have found wide applications in China since 1980. In oil refinement and the petrochemical processing industries, they have substituted for austenitic stainless steels in many types of equipment, valves, and pump parts. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on low and high temperature performance, and corrosion resistance as well as forming and joining. Filing Code: SS-706. Producer or source: Central Iron & Steel Research Institute.

Developing New Cast Austenitic Stainless Steels With Improved High-Temperature Creep Resistance

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Philip J. Maziasz ◽  
John P. Shingledecker ◽  
Neal D. Evans ◽  
Michael J. Pollard
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Creep Strength ◽  
Stainless Steels ◽  
Creep Resistance ◽  
Austenitic Stainless Steels ◽  
Creep Rupture ◽  
Particulate Filter ◽  
Alloy Development ◽  
Wide Range

Oak Ridge National Laboratory and Caterpillar (CAT) have recently developed a new cast austenitic stainless steel, CF8C-Plus, for a wide range of high-temperature applications, including diesel exhaust components and turbine casings. The creep-rupture life of the new CF8C-Plus is over ten times greater than that of the standard cast CF8C stainless steel, and the creep-rupture strength is about 50–70% greater. Another variant, CF8C-Plus Cu/W, has been developed with even more creep strength at 750–850°C. The creep strength of these new cast austenitic stainless steels is close to that of wrought Ni-based superalloys such as 617. CF8C-Plus steel was developed in about 1.5 years using an “engineered microstructure” alloy development approach, which produces creep resistance based on the formation of stable nanocarbides (NbC), and resistance to the formation of deleterious intermetallics (sigma, Laves) during aging or service. The first commercial trial heats (227.5 kg or 500 lb) of CF8C-Plus steel were produced in 2002, and to date, over 27,215 kg (300 tons) have been produced, including various commercial component trials, but mainly for the commercial production of the Caterpillar regeneration system (CRS). The CRS application is a burner housing for the on-highway heavy-duty diesel engines that begins the process to burn-off particulates trapped in the ceramic diesel particulate filter (DPF). The CRS/DPF technology was required to meet the new more stringent emissions regulations in January, 2007, and subjects the CRS to frequent and severe thermal cycling. To date, all CF8C-Plus steel CRS units have performed successfully. The status of testing for other commercial applications of CF8C-Plus steel is also summarized.

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