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Causes and prevention measures of crane welding cracks

Mar 20, 2020
Welding cracks are the welding defects that are mainly controlled in the crane manufacturing process. The existence of welding cracks affects the life of the product and determines the safety of the crane machine. It has sharp notches and large aspect ratios, is the most serious process defect of welding structural parts, which directly affects product quality and even causes severe accidents.
 
1. Classification of cracks:
A. Thermal cracks, including crystalline cracks, liquefaction cracks, high-temperature low-plastic cracks, high-temperature cavity-shaped cracks, and reheat cracks.
B. Cold cracks, including delayed cracks, thermal stress cracks, and lamellar tears.
 
2. Reasons:
A. The weld width is too large (the arc voltage is small and the current is large);
B. The bead is too small, especially fillet and root bead (welding speed is too fast).
C. Arc pit cooling at the end of the weld is fast.
 
3. Preventive measures:
A. Increase the arc voltage or reduce the welding current to widen the weld bead and reduce the penetration;
B. Slow down the welding speed;
C. Fill the arc pits appropriately.
 
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