perature interval is small, low liquidity, under the condition of fast cooling crystallization, gas extremely easily to escape to the appearance of porosity in the weld. So nickel and nickel alloy welding string cable should be used in energy, lower layer temperature, speed up the welding seam between the cooling speed, thoroughly remove before welding wire, parent metal groove in the oil, dirt, strict control of sulfur and phosphorus content in parent metal welding materials, to prevent the formation of cracks and pores.