Hello, today we're going to talk about hot cracking.
Hot cracking of steel castings usually occurs in the casting state.
Usually more heat shrinkage crack compact,
generally only after heat treatment or MT detection will show.
The crack is serrated,
but there is no epitaxial bifurcation of heat shrinkage crack.
If the crack has an opening,
it is dark and will oxidize obviously
because it is exposed to high temperature oxidation.
There are coarse grain boundary cracks, but only a little dendritic crystal.
Cracks usually occur along the grain boundary of the initial austenite,
but may also occur on the secondary surface.
It is often found in places where stress occurs after solidification.
It is closely related to thermal shrinkage cracking,
but it occurs in a short time after solidification
and the casting is not ductile at all.
Hot cracking occurs when the supporting force of the sand mold
is reduced due to the burning loss of the binder after
the solidification of the self-hardening sand mold casting.
This effect is more obvious for thick castings,
where the cooling rate is slow and the binder is burned out faster,
while the hot and brittle castings produce higher stress.
The direction of the crack can be used to determine the stress pattern
and therefore the location of the loss of support in the sand mold.
Pay attention to me, the youngest girl in the factory.
See you next time
Hot cracking of steel castings usually occurs in the casting state.
Usually more heat shrinkage crack compact,
generally only after heat treatment or MT detection will show.
The crack is serrated,
but there is no epitaxial bifurcation of heat shrinkage crack.
If the crack has an opening,
it is dark and will oxidize obviously
because it is exposed to high temperature oxidation.
There are coarse grain boundary cracks, but only a little dendritic crystal.
Cracks usually occur along the grain boundary of the initial austenite,
but may also occur on the secondary surface.
It is often found in places where stress occurs after solidification.
It is closely related to thermal shrinkage cracking,
but it occurs in a short time after solidification
and the casting is not ductile at all.
Hot cracking occurs when the supporting force of the sand mold
is reduced due to the burning loss of the binder after
the solidification of the self-hardening sand mold casting.
This effect is more obvious for thick castings,
where the cooling rate is slow and the binder is burned out faster,
while the hot and brittle castings produce higher stress.
The direction of the crack can be used to determine the stress pattern
and therefore the location of the loss of support in the sand mold.
Pay attention to me, the youngest girl in the factory.
See you next time
