Harmful factors of welding materials

(1) The main research object of welding labor health is fusion welding, among which open arc welding has the biggest labor health problems, submerged arc welding, and electro slag welding has the least problems.

(2) The main harmful factors of manual arc welding of coated electrodes, carbon arc gouging, and carbon dioxide gas shielded welding are soot produced in the welding process - welding soot. Especially electrode hand arc welding. And carbon arc gash, if long-term welding operation in a narrow working space environment (boiler, cabin, closed container, pipeline, etc.), and in the case of poor health protection, will cause harm to the respiratory system, serious prone to electric welding pneumoconiosis.

(3) Toxic gas is one of the main harmful factors in gas welding and plasma arc welding, and its concentration is relatively high, which will cause poisoning symptoms. In particular, ozone and nitrogen oxides are produced by arc radiation acting on oxygen and nitrogen in the air.

(4) Arc radiation is the common harmful factor of all open arc welding, and the electrooptic eye disease caused by it is a special occupational disease of open arc welding. Arc radiation can also damage the skin, giving welders skin conditions such as dermatitis, red spots, and small blisters. In addition, cotton fibers can be damaged.

(5) Argon tungsten arc welding and plasma arc welding, because the welder sets a high-frequency oscillator to help start the arc, there are harmful factors -- high-frequency electromagnetic field, especially the high-frequency oscillator working time is longer in the welder. High-frequency electromagnetic fields can cause nervous system and blood system diseases in welders.

Due to the use of thorium tungsten rod electrodes, thorium is a radioactive material, so there are radiological hazards (alpha, beta, and gamma rays), which may be present around grinding turbines where thorium tungsten rods are stored and sharpened.

(6) Plasma arc welding, spraying, and cutting, strong noise, in the case of poor protection, will damage the auditory nerve of the welder.

(7) The main harmful factors of non-ferrous metal gas welding are the oxide dust formed by the evaporation of molten metal in the air and the toxic gas from the flux.

Precautions for using welding materials

1, stainless steel electrode usually has titanium calcium type and low hydrogen type two. Welding current as far as possible using a DC power supply, is conducive to overcoming the welding rod redness and depth of penetration. Titanium calcium coated electrode is not suitable for all-position welding, only suitable for flat welding and fillet welding; Low - hydrogen - coated electrode can be all-position welding.

2, stainless steel electrode in use should be kept dry. In order to prevent cracks, pits, pores, and other defects, titanium-calcium coating was dried at 150-250℃ for 1 hour before welding, and the low-hydrogen coating was dried at 200-300℃ for 1 hour before welding. Do not repeat drying, otherwise, the skin is easy to fall off.

3. Clean the welding joint, and prevent the welding rod from being stained with oil and other dirt, so as not to increase the carbon content of the weld and affect the welding quality.

4, in order to prevent heating and intergranular corrosion, the welding current should not be too large, generally should be about 20% lower than the carbon steel electrode, an arc is not too long, fast cooling between layers, with narrow path welding is appropriate.

5, the arc of attention, can not be in the non-welding part of the arc, it is best to choose the same material with the welding arc plate to lead the arc.

6, should try to use short arc welding, arc length is generally 2-3mm, and the too long arc is easy to produce hot cracks.

7, transport bar: should use short arc rapid welding, generally do not allow lateral swing, its purpose is to reduce heat and heat affected zone width, improve the weld resistance to intercrystalline corrosion and reduce the tendency of thermal crack.

8, the welding of dissimilar steel should be carefully selected, to prevent the improper selection of welding rod thermal crack or high-temperature heat treatment caused by σ phase precipitation, and metal embrittlement. Reference to stainless steel and dissimilar steel electrode selection standards for selection, and take appropriate welding process.