Microanalysis for Design and Development of Improved High-Temperature Alloys

2001 ◽  
Vol 7 (S2) ◽  
pp. 544-545
Author(s):  
Philip J. Maziasz
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Power Plants ◽  
Austenitic Stainless Steels ◽  
High Temperature Creep ◽  
Alloy Development ◽  
Temperature Creep ◽  
Microstructural Design ◽  
Engineering Alloys ◽  
Processing Optimization

Alloy development can range from purely empirical, trial-and-error efforts to very theoretical, based on either fundamental first-principles calculations or computational-modeling using various kinds of data base inputs. However, “real-world” efforts to improve or optimize complex engineering alloys often cannot afford the time or cost of either extreme approach. in the past 10-15 years, an alloy development and processing optimization methodology has been developed that utilizes strategic microanalytical data (both detailed microstucture and microcompositional information) as the critical input that then enables efficient and effective design of various kinds of alloys for improved high-temperature performance [1-6]. in many cases, first time tests produce outstanding high-temperature creep or creep-rupture results, and enable improvements without trading off one property for another. This invited paper will highlight several examples of significantly improved creep resistance obtained using such microstructural design.This microstructural design methodology for high-temperature creep-resistance was initially developed for and demonstrated in austenitic stainless steels (Fe-14Cr-16Ni) designed for improved creep-strength and rupture resistance at 700°C and above for superheater and boiler tubing in advanced fossil power plants.

Analysis of Cracking Process in Conditions of High-Temperature Creep of Castings Form the Modified Superalloy IN-713C

2013 ◽  
Vol 212 ◽  
pp. 247-254
Author(s):  
Marek Cieśla ◽  
Franciszek Binczyk ◽  
Marcin Mańka
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Nickel Superalloy ◽  
Morphological Properties ◽  
Coarse Grain ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fine Grain ◽  
Initiation And Propagation ◽  
Cracking Process

mpact of complex modification and filtration during pouring into moulds on durability has been evaluated in this study in conditions of high-temperature creep of castings made from nickel superalloy IN-713C post production rejects. The conditions of initiation and propagation of cracks in the specimens were analysed with consideration of morphological properties of material macro-, micro-and substructure. It has been demonstrated that in conditions of high-temperature creep at temperature 980°C with stress σ =150 MPa creep resistance of the IN-713C superalloy increases significantly with the increase of macrograin size. Creep resistance of specimens made of coarse grain material was significantly higher than the resistance of fine grain material.

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.

Fe–Co–V alloy with improved magnetic properties and high-temperature creep resistance

2003 ◽  
Vol 93 (10) ◽  
pp. 7118-7120 ◽  
Author(s):  
S. Liu ◽  
S. Bauser ◽  
Z. Turgut ◽  
J. Coate ◽  
R. T. Fingers
Keyword(s):  
Magnetic Properties ◽  
High Temperature ◽  
Creep Resistance ◽  
High Temperature Creep ◽  
Temperature Creep

Creep Life Prediction of High Temperature Tube Materials for Power Plants

2004 ◽  
Vol 261-263 ◽  
pp. 1115-1122 ◽  
Author(s):  
Yu Sik Kong ◽  
Han Ki Yoon ◽  
Yi Hyun Park ◽  
Seon Jin Kim
Keyword(s):  
High Temperature ◽  
Power Plants ◽  
Initial Strain ◽  
Maintenance Cost ◽  
High Temperature Creep ◽  
Creep Life ◽  
Time Prediction ◽  
Temperature Creep ◽  
Long Time ◽  
Strain Method

The high temperature creep behaviors of heat machine systems such as aircraft engines, boilers and turbines in power plants and nuclear reactor components have been considered as an important and needful fact. There are considerable research results available for the design of high temperature tube materials in power plants, based on uni-axial tension creep tests. However, few studies on the Initial Strain Method (ISM) capable of securing repair, maintenance, cost loss and life loss have been made. In this method, a long time prediction of high temperature creep characteristics can be dramatically reduced through a short time experiment. The purpose of present study is to investigate the high temperature creep life of 1Cr-0.5Mo steel using the Initial Strain Method. The creep test was performed at 500°C, 550°C and 600°C under a pure loading. In the prediction of creep life for 1Cr-0.5Mo steel, the equation of ISM was superior to those of LMP. Especially, the long time prediction of creep life was identified to improve the reliability.

The Effect of Heat Treatment on Creep Resistance of Castings from the Modified Superalloy MAR-247

2013 ◽  
Vol 212 ◽  
pp. 229-236
Author(s):  
Marek Cieśla ◽  
Franciszek Binczyk ◽  
Marcin Mańka
Keyword(s):  
Heat Treatment ◽  
High Temperature ◽  
Creep Resistance ◽  
Nickel Superalloy ◽  
Grain Structure ◽  
Morphological Properties ◽  
High Temperature Creep ◽  
Temperature Creep ◽  
Fine Grain ◽  
Heat Treated

mpact of heat treatment on durability has been evaluated in this study in conditions of high-temperature creep of castings made from nickel superalloy MAR-247 post production rejects. Castings made in the processes of modification and filtration when pouring into moulds were subject to solubilization (1185°C/2 h) with subsequent ageing (870°C/20 h). It has been found on the basis of performed tests that in conditions of high-temperature creep at temperature 980°C with stress σ = 150 MPa the resistance of specimens of coarse-grain structure was significantly higher when compared to fine-grain material. The conditions of initiation and propagation of cracks in these specimens were analysed with consideration of morphological properties of material macro-, micro-and substructure. Moreover, it has been proven that creep resistance of heat treated MAR-247 superalloy significantly improves when compared to its condition after the process of modification only. Macrostructural changes in the MAR-247 superalloy that determine the increase of superalloy creep resistance after solubilization and ageing, as observed in the tests, were also examined.

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