After receiving the precision-cast stainless steel product and we did a Salt Fog Test after polishing , and the problem is shown in below picture.
But why does this problem occur?
There are shrinkage and porosity,blowhole and segregation.
①Shrinkage and porosity
Most metals shrink in volume when solidifying. If there is not enough liquid to replenish, pores will form. If the pores are concentrated in the last part of solidification, it is called shrinkage.
When the liquid metal solidified, if the gas is too late to escape, it will remain inside the ingot and form blowholes.
When uneven chemical composition of each part of the alloy is not uniform, it called segregation.
At last,please refer to the last LinkedIn we posted about Microstructure in practical cast ingot.