Impact values of steel and cast iron / low temperature
Impact values of steel and cast iron / low temperature
(OP)
Hi, can anybody help me. I am working an application which has to operate successfully at low temperatures (–40°c). As I see it, the main affect that the low temperature will have on the materials that we will be using (steel and cast iron) is a reduction in the impact value (Av measured in J). Although I have found references as to the minimum impact values of materials used for particular applications, I have not been able to find out how one can determine the minimum value necessary for a new application. The application is a hydraulic actuator where no impact or shocks other then normal pressure pulsation are to be expected.





RE: Impact values of steel and cast iron / low temperature
K = Yσ √πa
where Y is a constant depending on geometry
σ is applied stress
a is the allowable flaw size
Fracture occurs when K is greater than KIc. The are some approximations for relating fracture toughness and charpy impact energy (Barsom-Rolfe, etc.). ASM HANDBOOK Volume 19 Fatigue and Fracture and Deformation and Fracture Mechanics of Engineering Materials by R. W. Hertzberg are both excellent references on this subject. You can obtain more information on these references using the following links:
http://www.asminternational.org/Template.cfm?Section=BrowsebyTopic&template=Ecommerce/ProductDisplay.cfm&ProductID=10494
http://www.wiley.com/cda/product/0,,0471012149,00.html
RE: Impact values of steel and cast iron / low temperature
RE: Impact values of steel and cast iron / low temperature
RE: Impact values of steel and cast iron / low temperature
Mechanical Engineers > Activities > Boiler and Pressure Vessel engineering Forum
fracture toughness
Thread794-40581
As there are lots of Charpy test results as f(T) and most Kic values are for room temperaure, I found some very interesting equations given by arto and desertfox for relating Charpy results to fracture toughness & for converting Charpy results to different Ts.
Would someone please comment on their validity; I think maybe true for limited circumstances, but I am not an expert on mechanics.