Before welding the workpiece as a whole or part of the preheating to 700 ~ 600, the welding process is not less than 400, after the slow cooling to room temperature. Can effectively reduce the temperature of welded joint using heat welding method, thereby reducing stress, but also can improve the plastic parts, to avoid white tissue and crack.

Welding method is commonly used in gas welding and smaw. The commonly used cast iron welding gas welding wire, such as HS401 or HS402, CJ201 flux, to remove oxides. The gas preheating method is suitable for welding in small thin-walled parts. The welding rod is made of cast iron, cast iron electrode Z248 or steel cored electrode Z208, the method is mainly used for welding the thickness of the larger (greater than 10mm) cast iron parts.

Welding equipment heat welding method mainly heating furnace, welding torch, electric furnace (oil stove or furnace), the welding process is as follows:

1) welding preparation and preheating: oil and eliminate skin defects around the exposed oxide, metallic luster matrix: groove, groove depth of ordinary welding thickness 2/3, angle of 70 degrees to 120 degrees; the welding in the furnace in slow heating to 600 to 700 DEG C (not beyond 700 DEG C).

2) welding: neutral flame or weak carbonizing flame (not in welding molten steel flow, to one side) of base metal penetration, and then melt into the metal electrode; found in the weld pool appear white spots, fill in the suspension of the electrode metal, in the amount of flux, with the electrode will continue after the debris removed welding; weld seam after welding can get smooth, should be slightly higher than the cast iron appearance, and will overflow in the weld slag re condensation, to be cooled to half frozen state, wire along the casting appearance will be higher than the local shave.

3) the cooling after welding: the ordinary should be cooled to room temperature (usually need 48h above), also can be used to cover up the stone (plate) or carbon gray, so that the weld constitutes an average of the organization, while avoiding crack.