Shenyang zhongda steel structure engineering co. LTD.
Contact: mu guoyu.
Email address: firstname.lastname@example.org
Address: zhai jia development zone, tiexi district, shenyang city.
Zip code: 110178
Liaoning zhongda shengbang industrial co. LTD.
Contact: liu chang.
Email address: email@example.com
Address: no. 109, quanyun road, shenyang district, China (liaoning) free trade test zone.
Zip code: 110209
Telephone: 0086-24-89355770 89355771.
The construction steel structure has the advantages of light weight, short construction period, strong adaptability, rich appearance and convenient maintenance. Since the 1980s, China's construction steel structure has been developed unprecedentedly, with high-rise steel structure, space steel structure, bridge steel structure, light steel structure and residential steel structure mushroomed. Welding as a main connection method of building steel structure, physics, chemistry, metallurgy, materials, electronics, computer, automatic control and other disciplines of rapid development today, with the new technology, new material, new equipment, new technology emerge from time to time, the construction to play a more important role in the construction of steel structure. According to statistics, more than 50% of the steel needs to be welded and processed before being put into use. Therefore, the improvement of welding level is the key to realize rapid development of steel structure technology and ensure construction quality of construction steel structure.
Welding construction technology of high strength steel.
1.1 selection principle of welding materials.
Strong match. The strength, plasticity and impact toughness of the welding materials are higher than the minimum values of the parent material. The welding joints (weld and heat affected zone) are fully required to meet the minimum standards set by the parent material. The weld is plastic. When the thick plate is welded according to the thickness effect, the welding material should be selected and the welding material can be lower than 1/4 plate thickness. To meet the impact toughness requirements. It is necessary to select the toughness of welding material, so as to meet the requirements of steel specification.
1.2 evaluation method of high strength steel welding.
Carbon equivalent calculation method. The highest hardness test evaluation method for heat affected area. The critical fracture stress evaluation method is used in the test.
1.3 determination of minimum preheating temperature.
Crack test control. The minimum preheating temperature was determined according to the anti-crack test of oblique Y groove. Hardness control. According to a certain carbon equivalent of steel, its different thickness T joint fillet weld heat affected zone hardness is 350 hv corresponding cooling speed (540 ℃) look-up table to determine the welding line energy. The lowest preheating temperature was determined according to the crack sensitive index, the thickness of the plate, the degree of restraint, and the content of the molten metal diffusion hydrogen. The minimum preheating temperature is determined according to the heat input of the joint, the cooling time and the specific curve of the steel.
1.4 welding quality control.
Control heat input and cooling rate. Control welding current, voltage, welding speed and deposited metal 800 ℃ ~ 500 ℃ range of cooling time. To control the percentage of carbon/sulfur/phosphorus/nitrogen/hydrogen/oxygen in the weld. High quality basic low hydrogen welding material is selected, and good operation technique is used to fully maintain the stress and deformation control of molten pool metal (short arc, limit swing and inclination stability). High energy density, low heat input welding method, such as gas maintenance welding; With small line energy, multi-layer multi-channel welding; Reduce the Angle and clearance of weld groove and reduce the filling amount of molten metal. Using symmetrical groove, symmetry and rotation welding; Long welds shall be dissected or welded at the same time. Prevent deformation and stress concentration by jumping welding.
In short, the high strength steel welding for, should according to the steel reinforcement mechanism and supply condition, considering its performance requirements, selecting welding materials and test methods of its weldability, and make reasonable welding process, to guide the actual welding production. The welding of the steel should be mainly considered to reduce its cold crack tendency. During welding, the temperature and the energy of welding line should be strictly controlled to prevent weakening of joints.