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不久前,我们为某磷肥厂焊补一台定容式鼓风机叶片的裂纹。叶片材料为灰口铸铁,重300公斤,总长660毫米,几何形状为8字形。在同一端面上有两条裂纹,一条长600毫米;另一条约500毫米,同时处于叶片顶端约20毫米厚的薄弱处(图1)。本打算采用氧—乙炔热焊,但考虑到叶片是铸铁的,而中间串上的一根轴是45号钢,二者的热膨胀系数不同,加热后会影响其他地方产生裂纹,所以决定采取不预热气焊方法。根据是,裂纹出现在同一顶端,又是最薄弱地方,两条裂纹相差100毫米,用气焊的加热减应方法,先焊一条短的裂纹,第二条长裂纹可作为它自由膨胀和收缩的余地,使它不受任何限制,不会产生焊后裂纹;同时,它又为第二条裂纹创造了加热减应条件,当焊补第二条焊缝时,也不会产生焊后裂纹。再者,叶片本身与
Not long ago, we cracked a fixed capacity blower blade for a phosphate fertilizer plant. Leaf material gray cast iron, weighing 300 kg, a total length of 660 mm, the geometry of 8-shaped. There are two cracks on the same end, one 600 mm long; the other about 500 mm, while being at a weak point about 20 mm thick at the top of the blade (Figure 1). The intent is to use oxy-acetylene heat welding, but considering that the blade is cast iron, and the middle shaft is a 45-gauge steel, the two have different coefficients of thermal expansion, heating will affect other parts of the crack, so the decision not to take Preheat gas welding method. According to yes, the crack appears in the same top, but also the weakest place, the two cracks a difference of 100 mm, with gas welding heat reduction method, first welding a short crack, the second long crack as it can freely expand and contract It will be free from any restrictions and will not produce post-weld cracks. At the same time, it will create a heating and de-stressing condition for the second crack. When the second weld is repaired, no post-weld crack will occur. Moreover, the leaves themselves