We need your consent to use the individual data so that you can see information about your interests, among other things. Click "OK" to give your consent.
Standard Test Method for Determination of Slow Crack Growth Parameters of Advanced Ceramics by Constant Stress-Rate Flexural Testing at Elevated Temperatures
STANDARD published on 1.8.2013
Designation standards: ASTM C1465-08(2013)
Note: WITHDRAWN
Publication date standards: 1.8.2013
SKU: NS-11397
The number of pages: 14
Approximate weight : 42 g (0.09 lbs)
Country: American technical standard
Category: Technical standards ASTM
Keywords:
advanced ceramics, constant stress-rate testing, elevated temperatures, flexural strength, flexural testing, four-point flexure, slow crack growth, slow crack growth parameters, ICS Number Code 81.060.30 (Advanced ceramics)
Significance and Use | ||||||||||||||||||||||||||||||
4.1 For many structural ceramic components in service, their use is often limited by lifetimes that are controlled by a process of slow crack growth. This test method provides the empirical parameters for appraising the relative slow crack growth susceptibility of ceramic materials under specified environments at elevated temperatures. This test method is similar to Test Method C1368 with the exception that provisions for testing at elevated temperatures are given. Furthermore, this test method may establish the influences of processing variables and composition on slow crack growth as well as on strength behavior of newly developed or existing materials, thus allowing tailoring and optimizing material processing for further modification. In summary, this test method may be used for material development, quality control, characterization, and limited design data generation purposes. 4.2 In this test method, the
flexural stress computation is based on simple beam theory, with
the assumptions that the material is isotropic and homogeneous, the
moduli of elasticity in tension and compression are identical, and
the material is linearly elastic. The average grain size should be
no greater than one fiftieth (1/50) of the beam thickness.
4.3 In this test method, the test specimen sizes and test fixtures were chosen in accordance with Test Method C1211, which provides a balance between practical configurations and resulting errors, as discussed in Refs 4.4 In this test method, the slow crack growth parameters (n and D) are determined based on the mathematical relationship between flexural strength and applied stress rate, log σf = [1/(4.5 In this test method, the mathematical relationship between flexural strength and stress rate was derived based on the assumption that the slow crack growth parameter is at least n ≥ 5 4.6 The mathematical analysis of test results according to the method in 4.4 assumes that the material displays no rising R-curve behavior, that is, no increasing fracture resistance (or crack-extension resistance) with increasing crack length. It should be noted that the existence of such behavior cannot be determined from this test method. The analysis further assumes that the same flaw types control strength over the entire test range. That is, no new flaws are created, and the flaws that control the strength at the highest stress rate control the strength at the lowest stress rate. 4.7 Slow crack growth behavior of ceramic materials can vary as a function of mechanical, material, thermal, and environmental variables. Therefore, it is essential that test results accurately reflect the effects of specific variables under study. Only then can data be compared from one investigation to another on a valid basis, or serve as a valid basis for characterizing materials and assessing structural behavior. 4.8 The strength of advanced ceramics is probabilistic in nature. Therefore, slow crack growth that is determined from the flexural strengths of a ceramic material is also a probabilistic phenomenon. Hence, a proper range and number of test rates in conjunction with an appropriate number of specimens at each test rate are required for statistical reproducibility and design (4). Guidance is provided in this test method. 4.9 The elevated-temperature
strength of a ceramic material for a given test specimen and test
fixture configuration is dependent on its inherent resistance to
fracture, the presence of flaws, test rate, and environmental
effects. Analysis of a fracture surface, fractography, though
beyond the scope of this test method, is highly recommended for all
purposes, especially to verify the mechanism(s) associated with
failure (refer to Practice C1322).
|
||||||||||||||||||||||||||||||
1. Scope | ||||||||||||||||||||||||||||||
1.1 This test method covers the determination of slow crack growth (SCG) parameters of advanced ceramics by using constant stress-rate flexural testing in which flexural strength is determined as a function of applied stress rate in a given environment at elevated temperatures. The strength degradation exhibited with decreasing applied stress rate in a specified environment is the basis of this test method which enables the evaluation of slow crack growth parameters of a material. 1.2 This test method is intended
primarily to be used for negligible creep of
test specimens, with specific limits on creep imposed in this test
method.
1.3 This test method applies primarily to advanced ceramics that are macroscopically homogeneous and isotropic. This test method may also be applied to certain whisker- or particle-reinforced ceramics that exhibit macroscopically homogeneous behavior. 1.4 This test method is intended for use with various test environments such as air, vacuum, inert, and any other gaseous environments. 1.5 Values expressed in this standard test are in accordance with the International System of Units (SI) and IEEE/ASTM SI 10. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. |
||||||||||||||||||||||||||||||
2. Referenced Documents | ||||||||||||||||||||||||||||||
|
Do you want to be sure about the validity of used regulations?
We offer you a solution so that you could use valid and updated legislative regulations.
Would you like to get more information? Look at this page.
Latest update: 2024-04-23 (Number of items: 2 895 375)
© Copyright 2024 NORMSERVIS s.r.o.