What is the difference between the temperature of plasticity transition (drop hammer test) and the temperature of ductile-brittle transition?
Thread Content
There is no plastic transition temperature, which can be determined through a falling weight test in accordance with GB-T6803-2008. There is also another concept, the \"brittleness-to-toughness transition temperature,\" which is determined through a pendulum test in accordance with GB-T299-1994. What is the essential difference between these two concepts?
The tough-to-brittle transition temperature is the same as the ductile-to-indestructible transition temperature
This post was last edited by Pinocchio on 2016-11-16 at 16:28. Did the original poster type 299 instead of 229? GB/T 229-2007 \"Metallic materials – Charpy pendulum impact test method\": it is used to measure the Charpy impact energy at a specified test temperature, and this data is required for all materials used in GB pressure vessels ； GB/T 6803-2008 \"Method for determining the non-plastic transition temperature (NDT) of ferritic steels\" – used to measure the non-plastic transition temperature, and is only required in special cases. All are aimed at solving the problem of brittle fracture at low temperatures, but there are still conceptual differences. Find a textbook on metal materials and take a look. :lol
This post was last edited by Pinocchio on 2016-11-21 at 13:06. Additional note: The method in Appendix D (informative appendix) of GB/T 229-2007 can be used to determine the FATT (Fracture Appearance Transition Temperature) of materials, that is, the temperature at which the fracture pattern changes. Generally, the temperature at which the cross-sectional area of the specimen’s fracture surface reaches 50% is taken as the ductile-brittle transition temperature, denoted as FATT50. The result of the GB/T 6803 test is called NDTT (Nil-Ductility Transition Temperature), the temperature at which no plasticity transition occurs. It can be said that the purposes of the two are the same, but the testing methods differ. The main differences are: 1) Appendix D of GB/T 229 uses a pendulum, while GB/T 6803 uses a vertically falling hammer ； 2) The former sample has a V-shaped notch, while the latter requires welding crack initiation weld beads to create a square notch. 3) The former uses the fracture shape as a criterion, while the latter uses whether cracking occurs or not as a criterion ； The latter involves more testing steps, yields relatively smaller errors in the test results, and exhibits good repeatability.