(4) oxygen – acetylene flame alloy powder welding process to adapt to a variety of carbon steel, low alloy steel parts of the surface to strengthen or repair, but should pay attention to some of the characteristics of parts, when the matrix material linear expansion coefficient and alloy spray layer If the coefficient of linear expansion is larger than 12 × 10-6 / ℃ greater than 12 × 10-6 / ℃, you should be careful with this process, so as to avoid cracking, if the matrix metal and oxygen affinity greater elements such as Tungsten and molybdenum content of more than 3%, aluminum, magnesium, cobalt, titanium, molybdenum and other elements of the total content of more than 0.5% or steel in the sulfur content is more difficult to spray welding, because these materials and oxygen The role of easy to produce a dense and stable oxide film, blocking the wetting of the matrix alloy wetting effect, remelting liquid alloy will be beads like "sweat" to roll off, so the use of spray welding process, it should be noted The suitability of this process for the substrate material to be sprayed.