A, the thickness of 12mm below the plane ruler.
B, plate thickness ≥ 12mm, Y-shaped groove.
C, the minimum root is 7mm .. (see CBT/B3 190- 1997 for details).
2, CO2 welding
A, CO2 single-sided welding is V-groove, and the gap between plates is 6 (5 ~ 8 mm).
B, CO2 single-sided welding is mainly used for welds above 10mm.
C the butt joint with the thickness below 10mm can be V-shaped groove, leaving no gap and Y-shaped groove.
D, the plate thickness below 10mm can be opened with Y-groove, and the V-groove can be opened for slideway and final assembly.
B, CO2 single-sided welding groove angle is 40.
C, CO2 double-sided welding groove angle is 60.
3. Manual covered electrode welding with groove angle of 60.
Eight, ordinary marine steel
Generally, the grades A, B, D and E of hull structural steel are distinguished according to the impact temperature of steel, and the impact values of all grades of steel are the same, not according to the strength grade.
Grade A steel is the impact force at normal temperature (20℃).
Grade B steel is the impact force at 0℃.
Grade d steel is the impact force at -20℃.
Grade E steel is the impact force at -40℃.
High strength hull structural steel can be divided into AH32 DH32 EH32.
AH36 DH36 EH36
2. Preheating requirements for high-strength hull structural steel: All corners and butt joints with thicknesses of AH, DH and EH greater than 30mm shall be preheated to 120 ~ 150℃ before welding.
3, the plate thickness is less than or equal to ≤30mm, the ambient temperature is lower than 5℃, and it is preheated to 75℃; The ambient temperature is below 0℃ and preheated to 75 ~ 100℃.
3.TMCP steel (made in Japan) shall not be preheated before welding.
Six, efficient welding
1, the current intensity used per unit section.
2. Amount of deposited metal obtained per unit time
3. Quantity of welding materials consumed per unit time.
X. Various efficient welding methods and application parts
1, efficient manual welding
A, the frame vertical fillet welding adopts downward welding, and welding is carried out from top to bottom. Special downward covered electrode is adopted for welding from bottom to top. One covered electrode is150 ~ 200mm.
B, gravity welding is used to weld the long weld of the frame angle.
C, iron powder covered electrode welding (the coating contains 15 ~ 30% iron powder, which is used for all-position welding; Iron powder content more than 30%, used for right-angle welding without groove)
D, matters needing attention
* 1.5m frames cannot be welded down.
* Watertight welds cannot use downward welding.
* In case of downward welding, upward welding must be used at both ends of100 mm. ..
* Patches cannot be welded.
2, CO2 gas shielded welding
Semi-automatic CO2 welding (for jigsaw puzzles, frames and all-position welding)
B, CO2 automatic welding (used for frame fillet welding)
C, CO2 single-sided welding (for all-position splicing welding)
D. Gas-electric vertical automatic welding (used for vertical butt welds greater than 45 degrees)
E. CO2 automatic fillet welding with double wires and single molten pool (used for longitudinal bone welding on assembly line)
3. Automatic submerged arc welding
One, monofilament submerged arc welding automatic welding (splicing welding)
B, multi-wire submerged arc welding automatic welding (splicing, butt welding)
C, FCB method (flux copper pad single-side submerged arc automatic welding) is used for flat plate segmented assembly line splicing welding.
D, radio frequency method (flux pad single-sided submerged arc welding)
E.FAB method (automatic submerged arc welding on one side of fiber brick lining)
Precautions:
* Single-sided submerged arc welding Disadvantages: terminal crack.
Solution: elastic arc reduction plate and positioning welding position.
XI。 Hull deformation control
A, thermal shrinkage control (compensation), longitudinal and transverse 1mm/m (thickness above 30mm).
B, rigid fixed control (back of segmented fixture)
C. Anti-deformation control (reducing both sides of the section) shall be calculated as one thousandth of the section width.
D, slideway closed without allowance, (depending on the weight gap contraction of segment itself)
Twelve. Factors affecting welding deformation
1, welding groove type, the greater the angle, the greater the welding deformation. The smaller the groove angle, the smaller the deformation, but the change of weld crystallization direction will affect the mechanical properties of weld.
2, the thickness of the plate, the thicker the plate, the smaller the deformation.
3, welding specification, heat input (linear energy), a stands for current; The v above represents the voltage; A lower u represents speed.
Manual welding (linear energy) is the largest and the deformation is the largest.
CO2 welding wire has minimum energy and minimum deformation.
The number of CO2 welding layers shall not exceed 6mm.
* Splicing: weld the longitudinal weld first, and then weld the end weld.
4. Welding method: CO2 welding is the smallest, automatic submerged arc welding is the center, and manual welding is the largest.
5. Distribution of welding personnel: centered on the section, scattered around and symmetrically arranged.
6, welding sequence
Fillet weld: First weld the surface of non-positioning weld.
B long fillet welding peak: ① split welding method ② step-by-step push welding method.
C vertical angle welding: weld the upper part 1/3 first, and then weld the lower part 2/3.
D, plate and frame welding: firstly weld the joint of the splicing plate, then weld the vertical fillet weld, and then weld the flat fillet weld.
E, 300mm at both ends of the segmented frame is not welded, and 300mm at both ends of the frame is reserved for welding in the final assembly or berth.
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