The first thickness of 22mm high-strength steel, ordinary rolling marine DHN36, Kobelco wire feed the the DWS-43C φ1.6mm line test, test specifications are shown in Table 4, the mechanical test results are shown in Table 5.
Connector from a test situation, the tensile strength and the cold bending performance can meet the compliance requirements of the ship, -20 ℃ impact toughness in addition to the weld center managed to reach the base metal, the toughness of the other regions are quite low, so 2, the first three tests, appropriate to adjust the welding current, voltage. Test results, the vertical gas welding method, the adjustment of the welding current, voltage, although the control of the energy of the weld line a slight impact, but not critical, as compared with a test results, as the  Welding Cable line energy reduction, the impact toughness of the -20 ° C weld center tends to be improved, and the toughness of the weld and fusion line can basically meet the steel requirements, but the heat-affected zone i.e. fusion line 1mm, 3mm, 5mm, no improvement. In three trials, also 0 ℃ impact other areas of impact are to meet the requirements, in addition to the fusion line 1mm, 3mm does not meet the standard 34J, and there is a certain amount of wealth.

Welding speed due to the vertical gas welding wire extension length change automatically adjust the welding current, wire deposited rate the pool level rise fast welding speeds have been increased, so to change the vertical gas welding line energy , only by changing the molten pool size of the cross section, i.e. to change the welding groove angle and root gap is reduced to 35 °, and this in four trials will welding bevel angle is increased from 45 ° roots fell 4mm, from The test results, along with the sharp drop of the line energy connector 0 ° C, the weld heat affected zone is narrowed significantly improve impact toughness, but -20 ℃ fusion line 1mm, 3mm impact remains any increase, which shows that the steel sheet The material characteristics determine its impact toughness of welded joints to meet the of 0 ℃ shock requests only under certain process measures.
Provided by the above-described test procedures and test results, the vertical automatic gas welding joint impact toughness, especially the toughness of the heat affected zone impact is mainly affected by the energy of the weld line and a steel welding performance constraints, while the control of the energy of the weld lines depends primarily on the size of the weld cross section, inevitable in the actual production assembly gap ultra-poor, caused by the increase of the line energy, resulting in a decline in toughness To solve this problem, the key is to choose the amount of heat input sensitive marine high-strength steel.
5 DH36-TMCP steel vertical gas welding test
Conventional steel smelting technology, to strengthen the steel plate, commonly used to add carbon or alloy elements to improve the strength of steel, this is bound to lead to equivalent Ceq an increase of carbon affect the welding performance, and high-strength steel for grain refinement and prevent high temperature when coarse grains added Ti, Nb micro-alloying elements on the the joint impact toughness improvement in the state of large heat input welding is limited, some information on the Japanese shipbuilding industry has generally TMCP steel. TMCP technology originated in the online accelerated cooling process (OLAC), the TMCP process manufacturing marine high-strength steel, the mass percentage of carbon and alloying elements are relatively low, good strength and toughness by reducing the steel plate in the S and P impurity content, and strict control accelerated cooling the temperature in the rolling process, to be guaranteed. TMCP steel alloy elements, the carbon equivalent is relatively low, generally less than 0.36, while the ordinary bar Steel 0.40-0.45 weldability, crack resistance, even for efficient large heat inputWelding Electrodes, impact toughness can also meet the requirements