Hot Tensile Tests
At the moment, the as a rule acceptable and a large amount used method for studying burning ductility is the burning tensile test, where reduction in area at the final split is taken as a determine of the burning ductility.
A brand new type of high-temp. Tensile testing equipment has been developed on behalf of testing the burning cracking propensity of Metal. The equipment Allows the test rod, fitted in a tensile testing engine, to be melted down and to go hard at a programmed rate to simulate lump solidification. With the equipment a comparison was accomplished, with respect to warm cracking propensity, among "as-cast" and "in situ solidified" specimens for a carbon steel with 0.5% C.
The tendency for surface-crack proliferation was found to multiply with Nb and soluble Al addition and to decrease with a rise in the P level. Warm ductility was as well found to be affected in a related mode by these elements. The results have been interpreted in expressions of differences in the effectiveness of the precipitation in pinning the gamma grain boundaries for the duration of warp
Within the innovative burning forming process for sheet Irons, called burning stamping, it is achievable to join forming and quenching in individual process step. This affords the opportunity to manufacture components with multiplex geometric shapes, extreme strength and a least amount of springback which presently find applications as crash important components in the automotive industry.
A brand new tensile test method which permits the in situ measurement of the mechanical properties of a solidifying shell is described. These properties are of fantastic connotation in casting and welding processes. In the apparatus developed, the tensile stress is applied in a direction which is perpendicular to the growth axis of the columnar crystals so to facilitate, once alloys are tested, the mechanical behaviour of the mushy zone can be calculated, as well as its contribution to the mechanical strength of the shell. This is used in cement materials testing too, a new born industry with prominent future nowadays. This information cannot be obtained from standard tests made using a machine because, for example, control of the orientation of the solidification microstructure with respect to the tensile axis is too arduous. The present method was primarily calibrated by using pure aluminium, which had no associated mushy zone.
The scope to which the burning tensile test can be used to assess the association of Metal composition to the incidence of slanting cracking in unbroken casting has been evaluated. The influence of S, Ca, Ti, and Nb on the hot ductility of C-Mn-Al steels was investigated for the heat range 500-900 C and the results were compared with existing business-related data on the effect of these elements on crossways cracking.
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ABOUT THE AUTHOR
Daniel Garcia is manager of Ibertest Internacional Materials Testing