{"id":27955,"date":"2020-11-20T18:15:42","date_gmt":"2020-11-20T18:15:42","guid":{"rendered":"http:\/\/sitepourvtc.com\/?page_id=27955"},"modified":"2023-08-10T05:34:46","modified_gmt":"2023-08-10T05:34:46","slug":"ductile-brittle-transition-temperature","status":"publish","type":"page","link":"https:\/\/sitepourvtc.com\/nuclear-engineering\/materials-science\/material-properties\/ductility\/ductile-brittle-transition-temperature\/","title":{"rendered":"Ductile\u2013brittle Transition Temperature"},"content":{"rendered":"
Many steels exhibit ductile fracture at elevated temperatures and brittle fracture at low temperatures<\/strong>. The temperature above which material is ductile and below which it is brittle is known as the ductile-brittle transition temperature<\/strong> (DBTT), nil ductility temperature (NDT), or nil ductility transition temperature.<\/div><\/div>\n
\"Liberty<\/a>
Brittle fracture of the U.S. Liberty Ship Esso Manhattan<\/figcaption><\/figure>\n

As was written, the distinction between brittleness and ductility isn\u2019t readily apparent, especially because both ductility and brittle behavior are dependent not only on the material in question but also on the temperature<\/strong> (ductile-brittle transition) of the material. The effect of temperature on the nature of the fracture is of considerable importance, and many steels exhibit ductile fracture at elevated temperatures and brittle fracture at low temperatures<\/strong>. The temperature above which material is ductile and below which it is brittle is known as the ductile-brittle transition temperature<\/strong> (DBTT), nil ductility temperature (NDT), or nil ductility transition temperature. This temperature is not precise but varies according to prior mechanical and heat treatment and the nature and amounts of impurity elements. It can be determined by some form of drop-weight test (for example, the Charpy or Izod tests<\/strong>).<\/p>\n

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Ductile\u2013brittle Transition Temperature – Testing<\/h2>\n

\"ductile\u2013brittle<\/a>The ductile-brittle transition temperature<\/strong> (DBTT) is the temperature at which the fracture energy passes below a predetermined value (e.g., 40 J for a standard Charpy impact test). Ductility is an essential requirement for the steel construction of reactor components, such as the reactor vessel<\/a>. Therefore, the DBTT is of significance in the operation of these vessels. In this case, the grain\u2019s size determines the metal\u2019s properties. For example, smaller grain size<\/a> increases tensile strength, tends to increase ductility, and decreases DBTT. Grain size<\/a> is controlled by heat treatment in the specifications and manufacturing of reactor vessels. The DBTT can also be lowered by small additions of selected alloying elements such as nickel and manganese to low-carbon steels.<\/p>\n

Typically, the low alloy reactor pressure vessel steels are ferritic steels that exhibit the classic ductile-to-brittle transition<\/b> behavior with decreasing temperature. This transitional temperature is of the highest importance during plant heat-up.<\/p>\n

Failure modes:<\/p>\n