China's welding material industry has a higher degree of marketization. The technical content of ordinary low-grade welding rods and copper-plated welding wires in welding consumables is low, and the entry threshold is low. In recent years, serious overcapacity has appeared. With the increasingly fierce market competition, the industry has presented a large-scale, group-based business model. While some domestic enterprises erode the market through low-cost means, they are also accelerating the pace of product structure adjustments in order to occupy the high-end market. The following Xiao Bian will introduce to you the harmful factors and precautions of welding materials. Let's take a look.
The harmful factors of welding materials
(1) The main research object of welding work hygiene is melting welding, among which the work hygiene problem of open arc welding is the largest, and the problems of submerged arc welding and electroslag welding are the least.
(2) The major harmful factors of manual electrode arc welding, carbon arc gouging, and CO2 gas shielded welding are the dust and welding fumes produced during the welding process. Especially welding arc welding. And carbon arc gouging, if long-term operation environment in the narrow space of the environment (boiler, cabin, closed containers and pipelines, etc.) welding operation, and in the case of poor health protection, will cause harm to the respiratory system, serious and easy Suffering from welding pneumoconiosis.
(3) Toxic gas is a major harmful factor in gas welding and plasma arc welding. When the concentration is high, poisoning may be caused. Among them are ozone and nitrogen oxides, which are produced by the high temperature radiation of arcs acting on oxygen and nitrogen in the air.
(4) Arc radiation is a common harmful factor in all arc welding. The electro-optic eye disease caused by this is a special occupational disease in open arc welding. Arc radiation can also damage the skin, causing welders to suffer from dermatitis, erythema, and small blisters. In addition, cotton fibers can also be damaged.
(5) TIG welding and plasma arc welding, because the welding machine set high-frequency oscillator to help start the arc, so there are harmful factors - high frequency electromagnetic field, especially the welding machine with high frequency oscillator working time (such as Some factory-made argon arc welding machines). High-frequency electromagnetic fields can cause welders to suffer from diseases of the nervous system and blood system.
Due to the use of barium tungsten rod electrodes, barium is a radioactive material, so there are harmful radiation factors (alpha, beta and gamma rays), which may cause radiological hazards around the sharpened tungsten grinder.
(6) Strong noise occurs during plasma arc welding, spraying, and cutting, which can damage the welder's auditory nerves in the event of poor protection.
(7) The main harmful factors in non-ferrous metal gas welding are the oxide dust smoke formed by the molten metal evaporated in the air, and the toxic gas from the flux.
Precautions for using welding materials
1, stainless steel electrodes are usually titanium calcium and low hydrogen two. The use of a DC power supply for the welding current as much as possible helps to overcome the redness and shallow penetration of the welding rod. Ti-Ca-type coating electrode is not suitable for all-position welding, only suitable for flat welding and flat fillet welding; low-hydrogen type coating electrode can be all-position welding.
2. Stainless steel electrodes should be kept dry during use. In order to prevent defects such as cracks, pits, and pores, titanium-calcium-based materials are dried at 150-250°C for 1 h before skin welding, and low-hydrogen-type skins are dried at 200-300°C for 1 h before skin welding. Do not repeat the drying many times, otherwise the skin will peel off easily.
3, clean welding mouth, at the same time to prevent welding electrodes stained with oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of welding.
4, in order to prevent intercrystalline corrosion to prevent heating, welding current should not be too large, generally should be about 20% lower than carbon steel electrode, arc not too long, fast cooling between layers, suitable for narrow track welding.
5. When starting the arc, be careful not to start the arc at the non-welding site. It is best to use the arc plate with the same material as the weldment to start the arc.
6. Short-arc welding should be adopted as far as possible. The arc length is generally 2-3mm, and the arc is prone to hot cracks.
7. Operation: Short-arc rapid welding should be adopted, generally not allowed to swing laterally. Its purpose is to reduce the width of heat and heat affected zone, improve the ability of the weld to resist intergranular corrosion and reduce the tendency of hot cracks.
8. The welding of dissimilar steels should be carefully selected to prevent the occurrence of sigma phase precipitation and the embrittlement of the metal by preventing the occurrence of hot cracks due to improper selection of the electrodes or high temperature heat treatment. Select the stainless steel and dissimilar steel electrode selection standards, and take the appropriate welding process.
In the future, the development strategy of China's welding material products will be gradually transferred. Handmade products will be gradually replaced by high-efficiency and high-quality products with higher degree of automation. Manual electrode products will gradually develop toward high strength, high toughness, low hydrogen, and environmental protection to meet different types and welding requirements. Structure, different service conditions under different welding technology requirements.
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