Low-temperature submerged-arc automatic welding method for Q370qE steel

The invention discloses a low-temperature submerged-arc automatic welding method for Q370qE steel and belongs to the field of welding methods. In the low-temperature submerged-arc automatic welding method, the temperature condition during the whole welding process of the Q370qE steel at environment temperature of 0-minus 15 DEG C is controlled by the steps as follows: dehumidification and pre-heating of a parent metal before welding, drying and temperature keeping of a welding rod and welding flux, and temperature keeping and slow cooling on the welding zone after welding. Especially, during welding, a crawler-type ceramic electric heater which needs electrifying before heating is laid on and covers a welding joint and 100-150mm parts at two sides of the welding joint, so that the temperature of welding joint layers and passes is controlled to 160-200 DEG C, and the crawler-type ceramic electric heater can be adjusted manually to control temperature, so that the temperature among the welding joint layers and passes can be simply and conveniently controlled. After the whole welding process is subjected to such-ordered temperature control, the welding process can be prevented from being influenced by low temperature environment as much as possible; the cooling speed of the welding joint during the welding process is slowed, so that the cold cracking, hardness and brittleness possibilities of the welding joint are reduced; and the low-temperature impact toughness of the submerged-arc automatic welding joint of the Q370qE steel is effectively ensured, the impact dynamic load performance of a bridge steel structure is enhanced and the service life of a bridge is prolonged.