Flame straightening construction method of welding deformation of steel What?

Flame straightening construction method Hainan steel welding deformation What?
At present, Hainan steel has been widely used in the plant construction. The steel plant is the main component welding H type steel columns, beams, support. These components are present in the production process of welding deformation, welding deformation if not corrected, will not only affect the structure of the whole installation, but also reduce the safety and reliability engineering.
Welded steel design deformation technology to produce more than the allowable deformation range, should seek to be corrected to achieve conformity to product quality requirements. Practice has proved that the majority of the deformation member can be corrected. Correction methods are trying to create new modification to achieve counteract deformation has occurred.
Correction method widely used in the production process, mainly mechanical correction, flame straightening and integrated correction. But Flame straightening is a difficult operation to work, the means to acquire, temperature abuse will result in new and greater deformation member. Therefore, flame straightening have a wealth of practical experience. This paper made a rough analysis of the type of steel welding deformation correction method.
1, the type of welding deformation of steel and flame straightening
Hainan is the main component of steel welding H type steel columns, beams, support. Welding deformation often use the following three flame straightening methods: (1) linear heating; (2) dot heating method; (3) heating triangle. The following describes the different parts of the construction solutions.
The following is the heating temperature during flame straightening (made of low carbon steel)
Low temperature correction 500 degrees to 600 degrees Cooling: water
Temperature correction 600 degrees to 700 degrees Cooling: air and water
Temperature correction 700 degrees to 800 degrees Cooling: air
Note: When the heating temperature is not too high flame straightening, too high will cause the metal brittle, impact toughness. 16Mn not be cooled with water at high temperature correction, including the thickness tend to be larger or hardened steel.
Angular Distortion 1.1 flange plates
Correction H type steel columns, beams, support angular distortion. In the upper flange plate (aligned with the outer seam) longitudinal linear heating (heating temperature is controlled at 650 degrees), pay attention to the heating range does not exceed the scope of the control of the two solder feet, so do not use water to cool. When the wire is heated to note: (1) should not be repeated heating in the same position; (2) the heating process should not be watered. These two points are flame straightening general principles.
1.2 columns, beams, braces and arch under torsion and bending
First, the flange plate against longitudinal welds, from the middle to the ends for linear heating, bending deformation can be corrected. To avoid bending and distortion, plus two tropical to synchronize. Can be taken to correct the low temperature or temperature correction method. This approach helps to reduce welding stress, but this method is also available in a larger longitudinal shrinkage transverse shrinkage, difficult to master.
Second, the flange plate for linear heating, heating on the web for the triangle. In this way the correction columns, beams, bending brace, the effect is significant, the transverse width of the linear heating and generally 20-90mm, thickness h, the heating width narrower, the width of the heating process should be extended to both sides of the middle. Linear heating is preferably carried out simultaneously by two, and then were heated should not exceed the width of the triangle triangle 2 times the plate thickness, corresponding to the base of the triangle and the wing plate width equal to the linear heating. Heating triangle from the top and from the center to the sides extended until the end of the heating layers until the triangle. When the heating temperature is not too high the web, or cause deformation of the recess, it is difficult to repair.
Note: The above method is also applicable to the triangle next to the heating curve correction member. It should be heated using temperature correction, watering less.
1.3 columns, beams, support web wave transformation
To find the first corrective wave transformation raised crest, with hand hammer corrective dot heating method. Heating dot diameter is generally 50 ~ 90mm, when the plate thickness or undulating area larger diameter should be enlarged, according to d = (4δ + 10) mm (d is the diameter of the heat spots; δ is thickness) calculated value heating. Grilled mouth as from crest spiral movement, using temperature correction. When the temperature reaches 600 to 700 degrees, the hand hammer on the edge of the heating zone, and then the big hammer hand hammer, metal by squeezing the heating zone, cooling contraction after the flare. Correction should avoid excessive shrinkage stress. After straightening a dot and then heated second peak point, the method above. To speed up the cooling rate of the Q235 steel may be water cooled. This correction method belongs dot heating method, the distribution of heat spots can form dense plum-shaped or chain-shaped point. Note that the temperature should not exceed 750 degrees.
2. Conclusion
Flame straightening caused by stress and stress are the same as the welding stress. Internal stress generated by correcting improper welding stress and load stress superposition, make columns, beams, braces vertical stress exceeds the allowable stress, resulting in reduced bearing safety factor. Therefore, in the manufacture of steel must be careful, try to adopt reasonable measures to reduce the deformation process, may try to use mechanical correction when correction. When the flame had to use the correction should note the following:
1. Roast the location can not be near the maximum stress in the main beam cross-section;
2, warming himself at the correction area on a cross-section should not be too large, choose a few to more cross-section;
3, to use the point-like heating methods to improve the stress state of the heating zone;
4, the heating temperature is preferably not more than 700 degrees.