Causes of shrinkage on the back of the ceramic gasket

Causes of shrinkage on the back of the ceramic gasket

2020-09-02 15:25:22

Ceramic welding backing is suitable for welding processes in shipbuilding, bridges, boilers, pressure vessels, steel structures and other industries. A paste-type ceramic welding liner for single-sided butt welding of general structural steel and general low-alloy structural steel in flat, vertical and horizontal positions. It is easy to operate. When the ceramic backing is normally welded, the condition of the mold body around the molten pool is: the upper part is arc heating, the two sides are metal, and the lower part is the ceramic backing. Due to the heating effect of the arc above the molten pool, the temperature is high; the crystallization of the molten pool is bottom-up crystallization.

When    the arc is extinguished, the conditions of the dies around the molten pool are: the upper part cools naturally, the metal on both sides cools quickly, and the lower ceramic liner has the effect of heat preservation and cools slowly.

  When the arc is extinguished, the heating effect of the arc above the molten pool is removed, and the insulation effect of the ceramic liner under the molten pool is removed. The upper part of the molten pool is cooled and crystallized first. The lower part of the molten pool cools slowly and crystallizes, and shrinkage holes are formed on the back.