Crack geometry factor and the structural sensitivity of the corrosion crack resistance of low-alloy steels in long-term loading

1984 ◽  
Vol 19 (5) ◽  
pp. 373-381
Author(s):  
O. N. Romaniv ◽  
G. N. Nikiforchin ◽  
A. Z. Student
Keyword(s):  
Crack Resistance ◽  
Low Alloy Steels ◽  
Geometry Factor ◽  
Structural Sensitivity ◽  
Crack Geometry ◽  
Corrosion Crack Resistance ◽  
Alloy Steels

Atmospheric Corrosion in Marine Environments

CORROSION ◽  
1978 ◽  
Vol 34 (12) ◽  
pp. 433-437 ◽  
Author(s):  
R. A. LEGAULT ◽  
V. P. PEARSON
Keyword(s):  
Corrosion Behavior ◽  
Atmospheric Corrosion ◽  
Low Alloy Steels ◽  
Marine Environments ◽  
Weight Losses ◽  
Alloy Steels

Abstract It has been demonstrated that the natural atmospheric corrosion behavior of low alloy steels in marine environments can be accurately described by an equation of the form: ΔW = KtN. With this relationship, reliable predictions of long term weight losses can be made from as few as two sets of determinations obtained in relatively short exposures. The reliability of this relationship has also been established for galvanized and aluminized steels.

scholarly journals EVALUATION OF CHARACTERISTICS OF RESISTANCE OF PROPAGATION OF CORROSION- FATIGUE CRACKS OF LONG-TERM OPERATED DRILL PIPES

2021 ◽  
pp. 111-122
Author(s):  
О. Yu. Vytyaz ◽  
R. S. Hrabovskyi
Keyword(s):  
Fatigue Crack ◽  
Crack Resistance ◽  
Corrosion Fatigue ◽  
Fatigue Cracks ◽  
Drill String ◽  
Drilling Mud ◽  
Corrosion Fatigue Crack ◽  
Corrosion Crack Resistance ◽  
Fatigue Crack Development

The aim of the proposed article is to determine the patterns of the corrosion-fatigue cracks in long-term operational metal elements of drill strings (steel 45, 36G2S, 40HN) when drilling wells in corrosive environments (drilling fluid "Biocar", potassium polymer mud and on the air). Based on the obtained results of experimental studies, diagrams of cyclic corrosion crack resistance for the studied systems "metal - medium" were drawn. The cyclic crack resistance characteristics of long-used metals of drill string elements are determined - the values of constants (C and n) in power dependence of Paris, as well as the values of threshold and critical stress intensity factory. The influence of drilling mud of the corrosion crack resistance of the investigated metals of drill string elements was estimated quantitatively. In particular, in the environment of drilling mud "Biocar" the process of corrosion-fatigue crack development in the studied metals of the elements of drill strings is not significantly, in the range of 1-5%, differs from the development of fatigue crack on the air. Whereas in the potassium polymer drilling mud media, the rate of corrosion-fatigue cracks development in the investigated metals of the drill strings elements significantly, in the range of 15-35%, differs from the development of fatigue cracks on the air. It is established that under the influence of working loads the process of the corrosion-fatigue crack development in long-operated elements of drilling string is accelerated by more than 10% in the media of the potassium polymeric drilling mud than in the environment of drilling mud "Biocar".

On the definition of the local brittle fracture criterion to predict the crack resistance of high-strength steel

2020 ◽  
pp. 114-134
Author(s):  
A. V. Ilyin ◽  
A. A. Lavrentiev ◽  
A. V. Mizetsky
Keyword(s):  
Brittle Fracture ◽  
Crack Resistance ◽  
Large Angle ◽  
Energy Condition ◽  
High Strength ◽  
Low Alloy Steels ◽  
Structural Barriers ◽  
Steel Sheets ◽  
Alloy Steels ◽  
Definition Of

The use of local brittle fracture criteria for predicting the crack resistance of low-alloy steels is a generally accepted approach. The paper analyzes the possibility of its use for experimental melts of highstrength low-alloy steel sheets with yield strength of about 1000 MPa, the structural state of which was previously studied. Cylindrical specimens with an annular notch of three types differing in the stress-strain state in the net cross-section were tested. It is found that the use of the simplest formulation of such a criterion in the form of an energy condition for the propagation of microcracks through structural barriers (large-angle grain boundaries) gives acceptable results for notched specimens made of metal with different grain sizes, and allows linking these results with the crack resistance of the studied materials.

A Case Study in Temper Embrittlement of Fluidized Catalytic Cracking Components

2014 ◽  
Author(s):  
Matthew Bowen ◽  
William F. Newell ◽  
Jorge Penso
Keyword(s):  
Brittle Fracture ◽  
Catalytic Cracking ◽  
Temper Embrittlement ◽  
Charpy Impact ◽  
Impact Testing ◽  
Low Alloy Steels ◽  
Microstructure Observation ◽  
Fluidized Catalytic Cracking ◽  
Alloy Steels

As described in API RP 571, temper embrittlement is the reduction in toughness due to a metallurgical change that can occur in some low alloy steels as a result of long term exposure in the temperature range of about 650°F to 1070°F (343°C to 577°C). The loss of toughness is not evident at operating temperatures; however, equipment that is temper embrittled may be susceptible to brittle fracture during start-up and shutdown. 2.25 Chromium 1 Molybdenum steel used in the petrochemical industry is known to be susceptible to temper embrittlement. Most guidance to prevent temper embrittlement is oriented to heavy wall hydroprocessing reactors. In this work, a case history is presented where Fluidized Catalytic Cracking (FCC) components less than one inch in thickness exposed to temperatures in the 900°F to 1000°F (482°C to 538°C) range experienced temper embrittlement. Metallurgical analysis that included chemical analysis, microstructure observation, and charpy impact testing at different temperatures before and after heat treatment helped to identify the embrittlement cause. Several considerations to mitigate the risk in the short term including inspection, definition of minimum metal temperature to prevent brittle fracture, fitness for service, and modification of operational procedures, as well as long term considerations, including pipe component replacement, are described. Additional work regarding the selection of filler metals, welding procedure qualification tests that include step cooling tests, and learning that included bead sequence and heat input controls are also described. Applicable API RP 934-A [Ref. 6] recommendations were incorporated into the project specification for this work, such as the consideration of chemical restrictions for this alloy, not only for heavy wall applications but also for thinner wall applications working in the temper embrittlement range.

Determination of the crack resistance of low-alloy steels for main pipelines

1987 ◽  
Vol 23 (2) ◽  
pp. 177-181 ◽  
Author(s):  
P. D. Odesskii ◽  
V. A. Ratov ◽  
O. N. Vinkler
Keyword(s):  
Crack Resistance ◽  
Low Alloy Steels ◽  
Main Pipelines ◽  
Alloy Steels

Characterization of Precipitation Process in T24 Steel after Long–Term Ageing

2012 ◽  
Vol 186 ◽  
pp. 296-300
Author(s):  
Grzegorz Golański ◽  
Joanna Kępa ◽  
Paweł Wieczorek ◽  
Krystian Prusik
Keyword(s):  
Power Industry ◽  
Precipitation Process ◽  
Low Alloy Steels ◽  
Air Atmosphere ◽  
Thin Foils ◽  
Bainitic Steels ◽  
Base Steel ◽  
Alloy Steels ◽  
Steam Parameters

The T24 steel belongs to a new group of bainitic steels introduced currently to the power industry. Higher requirements connected with applying higher steam parameters in power units are the reason why the low-alloy steels used so far can no longer be applied. Therefore, new T24 steel has been developed in Europe on the basis of 10CrMo9-10 (10H2M) steel, which has been used in the power industry for many years, as a result of modification in its chemical composition. This modification consisted in introducing additions and microadditions of titanium, vanadium, boron and nitrogen into the base steel. As a result of the modification the new-found T24 steel is characterized by higher mechanical properties in comparison with the base steel, which allows to use the steel for tight shields in the new supercritical power units. The material for research was low-alloy bainitic T24 steel. Samples for examination were taken from a pipe section of the following size: outside diameter 44.5mm, wall thickness 7mm. Samples were isothermally aged in the air atmosphere, at the temperature of 580°C and at times up to 12 000 hours. Changes in the microstructure were observed and recorded by means of high-resolution electron microscope, JOEL JEM 3010. Identification of the precipitates was made using carbon extraction replicas and thin foils with the SAED method. The aim of research was the analysis of precipitation processes. They are extremely important in the context of long-term service and maintaining strength parameters above the minimum level. The tests were performed on T24 steel for the as-received condition (after heat treatment) and after 12 000 hours of ageing at the temperature of 580°C. The research made it possible to determine the morphology of precipitates. It also allowed to establish the sequence of precipitation process for the examined steel.

scholarly journals Forecasting the distribution of precipitate diameters in the presence of changes in the structure of the material

2017 ◽  
Vol 62 (1) ◽  
pp. 273-280 ◽  
Author(s):  
A. Zieliński ◽  
M. Miczka ◽  
G. Golański
Keyword(s):  
Low Alloy Steels ◽  
Diameter Measurement ◽  
High Chromium ◽  
Material Condition ◽  
Forecasting Methods ◽  
Alloy Steels ◽  
Steel Grades ◽  
Long Term Impact ◽  
Degradation Degree

AbstractThe results of investigations on the microstructure of T23 and T24 low-alloy steels as well as P91 and P92 high-chromium steels in the as-received condition and after 70.000 h annealing at 550-650°C are presented. The quantitative analysis of the existing precipitates was performed for representative images of microstructure. The statistical analysis of collected data allowed the parameters of a selected theoretical statistical distribution to be estimated. A forecast of average precipitate diameter and standard deviation of such a distribution for the time of 100,000 hours at 550 and 600°C for T23 and T24 steels and at 600 and 650°C for P91 and P92 steels was calculated. The obtained results of investigations have made it possible to compare changes in the microstructure of various steel grades due to long-term impact of elevated temperature. They have also confirmed the possibility of using, in evaluating the degradation degree of materials in use, the forecasting methods that derive from mathematical statistics, in particular the theory of stochastic processes and forecast by analogy methods. The presented approach allows the development of a forecast of precipitate diameter probability density under the microstructure instability conditions for selected steel grades. The assessment of material condition that takes into consideration, but is not limited to, the precipitate diameter measurement is useful as an assessment component in estimating the time of safe service of power unit elements working under creep conditions.

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