Micro shrink / porosity in ASTM Keel Block design

[avekaria]

Guys,

I am having an issue at out steel plant. We pour 1025 steel. We have been using chill blocks on the ASTM Keel Block to prevent micro-shrink/micro-porosity. The fracture ends of the tensile test shows circular silver spots, which I am correlating to micro-shrink/micro-porosity.

Research has been in vain. Can anybody confirm my deductions as well as has anybody experience shrink/porosity in keel blocks. As a result the elongation and Reduction in Area values are low.



Thank you

 

[TVP]

You need to cross-section your parts/tensile specimens and observe them using a microscope to detect microstructure, including microporosity due to solidification shrinkage.