Hastelloy C-276 is a nickel-based stainless steel with excellent corrosion resistance. It is widely used in various pipes, containers, heat exchangers, etc. in chemical equipment. Many techniques need to be paid attention to during the welding construction process to ensure that the welded parts corrosion resistance.
1. Cleaning before welding
Since oxides, dirt, etc. will reduce the corrosion resistance of the alloy, the weld must be fully cleaned before welding. Mechanical cleaning method can be used, and the welding seam can be polished with a grinding wheel to expose the metallic luster on the surface. The cleaning width should be more than 100mm. After cleaning, wash with alcohol-free solvent to remove all dirt.
2. Use DC forward welding method
DC forward welding heat input is smaller, the weld quality is better, and the heat affected zone can be minimized, thereby ensuring that the corrosion resistance of the weld and heat affected zone is reduced. Use DC ENiCrMo-4 welding wire and ERNiCrMo-4 welding rod for welding.
3. Use argon gas shielded welding
In order to prevent oxidation caused by oxygen in the air, argon gas protection welding should be used. Argon gas has a high protective effect and can minimize the oxygen content of the molten pool, thereby reducing non-metallic inclusions in the molten pool and ensuring the quality of the weld.
4. Welding groove design and preheating
Hastelloy C-276 is prone to thermal cracks during the welding process, so the welding groove should adopt a small slope and be fully preheated before welding. The preheating temperature is 100-150°C. Preheating can release residual stress, expand particle size, reduce heat input, thereby reducing the occurrence of thermal cracks.
5. Control interlayer temperature and heat input
To prevent the formation of σ phase, the interlayer temperature should be controlled below 90°C. At the same time, small current and fast welding methods should be used to reduce heat input and prevent overheating to reduce the formation of σ phase.
6. Pay special attention to the closing arc.
Hastelloy C-276 is particularly prone to thermal cracks at the arc closing area, so the arc crater must be filled when the arc is closing, and the arc closing area must be fully polished and cleaned before re-starting the arc. These two measures can effectively inhibit the occurrence of thermal cracks.
7. Post-weld heat treatment
The corrosion resistance of Hastelloy C-276 will decrease after welding. In order to restore the corrosion resistance of the base metal, solution heat treatment is required. The solid solution heat treatment process is to heat at 1040-1150°C for 2 minutes, and then quickly cool to the black body state (around 400°C). After solid solution heat treatment, the corrosion resistance of the welded parts can be effectively improved.
8. Pay attention to the cleanliness of welding tools
Welding tools must be specially used for Hastelloy alloys and must be clean to avoid introducing foreign elements such as sulfur and carbon, which may affect the performance of the alloy. Temperature measuring chalk and marking ink should be used as little as possible. The grinding wheel should be a cathode grinding wheel with an inorganic binder to prevent the introduction of organic matter.
9. Other matters needing attention
Position welding should be the same as the formal welding process. Local hardening caused by forced assembly is not allowed. Metals with low melting points should not be in direct contact with the workpiece. The manufacturing process should limit the use of organic matter.
Through the above nine aspects of pre-welding preparation, welding process control and post-weld treatment, the corrosion resistance of Hastelloy C-276 welded parts can be guaranteed to the greatest extent. By selecting reasonable welding process parameters and taking effective measures to prevent defects, ideal welding results can be obtained by welding Hastelloy C-276.
Tianjin Anton Metal Manufacture Co., Ltd. is a company specializing in the production of various nickel-based alloys, Hastelloy alloys and high-temperature alloy materials. The company was established in 1989 with a registered capital of 10.0 million, specializing in the production and sales of alloy materials. Anton Metal’s products are widely used in aerospace, chemical industry, electric power, automobile, nuclear energy and other fields, and can also provide customized alloy material solutions according to customer needs. If you need to know the price consultation of alloy materials or provide customized alloy material solutions, please feel free to contact the sales staff.
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Post time: Nov-25-2023
