Harmful factors of welding materials – what should be considered when using them?

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China’s welding materials industry is highly market-oriented. Ordinary, low-grade electrodes and copper-coated welding wires used in this industry have low technical complexity and require minimal entry barriers; as a result, there has been severe overcapacity in these areas in recent years. As market competition intensifies, the industry is moving toward larger-scale, group-based business models. While some domestic companies are encroaching on the market by offering lower prices, they are also accelerating the adjustment of their product portfolios in an effort to capture the high-end market. Next, I will introduce the harmful factors of welding materials as well as the precautions to take. Let’s take a look together. Harmful factors of welding materials. (1) The main subject of study in occupational health related to welding is fusion welding; among these, open-arc welding poses the greatest occupational health problems, while submerged arc welding and electroslag welding present the fewest problems. (2) The main harmful factor in shielded metal arc welding, carbon arc air gouging, CO2 gas shielded welding, etc., is the fumes generated during the welding process—welding fumes. Especially shielded metal arc welding. Similar to carbon arc air gouging, if welding operations are carried out for extended periods in confined spaces (such as boilers, ship compartments, sealed containers, and pipelines), especially under poor hygiene conditions, it can be harmful to the respiratory system; in severe cases, it may lead to welder’s pneumoconiosis. (3) Toxic gases are a major harmful factor in gas welding and plasma arc welding; high concentrations can cause poisoning symptoms. In particular, ozone and nitrogen oxides are produced when the high-temperature radiation from the electric arc acts on oxygen and nitrogen in the air. (4) Arc radiation is a harmful factor common to all open arc welding processes, and the electro-optic eye disease caused by it is a specific occupational disease associated with open arc welding. Arc radiation can also damage the skin, causing welders to suffer from skin conditions such as dermatitis, erythema, and small blisters. Furthermore, it will also damage the cotton fibers. (5) In tungsten inert gas welding and plasma arc welding, since the welding machines are equipped with high-frequency oscillators to facilitate arc ignition, there are harmful factors present—namely, high-frequency electromagnetic fields. This is especially true for welding machines where the high-frequency oscillator operates for extended periods of time (such as certain argon arc welding machines made in some factories). High-frequency electromagnetic fields can cause diseases of the nervous and blood systems in welders. Due to the use of thoriated tungsten rod electrodes, thorium is a radioactive substance; therefore, there are harmful radiation factors (alpha, beta, and gamma rays). Around areas where thoriated tungsten rods are stored and ground on grinders, there is a risk of radioactive hazards. (6) Plasma arc welding, spraying, and cutting generate intense noise; in the absence of proper protection, this can damage the welder’s auditory nerves. (7) The main harmful factors in gas welding of non-ferrous metals are oxide dust and fumes formed when molten metal evaporates into the air, as well as toxic gases originating from the flux. Precautions for using welding materials: 1. Stainless steel welding electrodes generally come in two types: titanium-calcium type and low-hydrogen type. Whenever possible, a DC power source should be used for the welding current, as this helps to overcome electrode redness and shallow penetration. Welding electrodes with a titanium-calcium type coating are not suitable for welding in all positions; they are only appropriate for flat welding and groove welding ； Welding electrodes with low-hydrogen coatings can be used for all-position welding. 2. Stainless steel welding electrodes should be kept dry when in use. To prevent defects such as cracks, pits, and pores, titanium-calcium fluxes are dried at 150–250°C for 1 hour before welding, while low-hydrogen fluxes are dried at 200–300°C for 1 hour before welding. The drying process should not be repeated multiple times; otherwise, the coating is prone to peeling off. 3. Clean the weld area thoroughly; at the same time, prevent the welding electrode from getting contaminated with oil and other dirt, so as to avoid increasing the carbon content in the weld and affecting the welding quality. 4. To prevent intergranular corrosion caused by heating, the welding current should not be too high; it is generally advisable to use a current level that is about 20% lower than that used with carbon steel electrodes. The arc length should also be kept short, and rapid cooling between layers is necessary, with narrow weld paths being preferred. 5. Be careful when starting the arc; do not start it at areas that are not to be welded. It is best to use an arc-starting plate made of the same material as the workpiece for starting the arc. 6. Short-arc welding should be used as much as possible; the arc length is generally 2-3 mm, as an overly long arc can easily cause thermal cracks. 7. Welding technique: Short arc welding at high speed should be used; lateral movement is generally not allowed. The purpose of this is to reduce heat input and the width of the heat-affected zone, thereby enhancing the weld’s resistance to intergranular corrosion and minimizing the tendency for hot cracks. 8. When welding dissimilar steels, welding electrodes must be selected with caution to prevent hot cracks caused by improper electrode selection or the precipitation of the σ phase after high-temperature heat treatment, which could render the metal brittle. Select the electrodes in accordance with the selection criteria for welding stainless steel and dissimilar steels, and adopt appropriate welding procedures. The development strategy for welding material products in China is gradually shifting, with highly automated, high-performance products replacing manual ones. Manual welding rod products are evolving toward higher strength, greater toughness, lower hydrogen content, and improved environmental compatibility, in order to meet the various welding technical requirements associated with different types of products, welding structures, and operating conditions.