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AWS A 5.4 E347-16
1kg,2kg,5kg,10kg,20kg
1lb;2lb;4.5lb;11lb;15lb;20lb;33lb;44lb
1.6mm,2.0mm,2.4mm,3.2mm,4.0mm,5.0mm
1/16 ″in;5/64″in;3/32″in;1/8″in;5/32″inch
Acceptable (design the pack with your logo)
15 Days
Product Description
The **AWS A5.4 E347-16** welding electrode is primarily characterized by its **stabilized composition** with **Niobium (Columbium)**. This crucial alloying element prevents **sensitization** or **intergranular corrosion** in the weld metal, especially when the welded component is exposed to elevated temperatures. It ensures long-term integrity and corrosion resistance, making it ideal for high-temperature service environments in various industries.
The "347" in the **E347-16** classification directly refers to its stabilization with **Niobium (Columbium, Nb)**. This element forms stable niobium carbides, which effectively "tie up" carbon atoms, preventing them from combining with chromium to form detrimental chromium carbides at grain boundaries. This stabilization mechanism is critical for maintaining the weld's **corrosion resistance** when subjected to temperatures within the sensitizing range, unlike unstabilized grades.
**E347-16** prevents **intergranular corrosion** through the addition of **Niobium (Columbium)**. During welding or subsequent high-temperature exposure (425°C to 850°C), carbon atoms typically combine with chromium to form chromium carbides at grain boundaries, depleting chromium in adjacent areas. Niobium has a stronger affinity for carbon than chromium; it preferentially forms stable **niobium carbides**, thus leaving the chromium free to maintain the protective passive layer. This ensures the weld metal retains its full corrosion resistance, even after exposure to sensitizing temperatures.
The "-16" in the **E347-16** classification denotes a **rutile-titania type flux coating**. This coating is known for providing excellent welding characteristics, including a very stable and smooth arc, minimal spatter, good bead appearance with a finely rippled finish, and easily removable slag. The rutile coating also allows for operation with both **AC (Alternating Current)** and **DCEP (Direct Current Electrode Positive)** polarity, offering versatility for different welding power sources and applications, contributing to its ease of use in stainless steel fabrication.
Yes, **E347-16** electrodes are generally classified for **all-position welding**. This includes flat (1F/1G), horizontal (2F/2G), vertical-up (3F/3G), and overhead (4F/4G) positions. The stable arc and good puddle control provided by the "-16" rutile coating make it a versatile choice for fabricating various stainless steel structures, especially in piping systems and pressure vessels where welding needs to be performed in different orientations, ensuring high-quality stainless steel welds.
**E347-16** electrodes are designed for use with both **AC (Alternating Current)** and **DCEP (Direct Current Electrode Positive)**. While DCEP is often preferred for stainless steel welding as it generally provides a more stable arc, better penetration, and a smoother bead, the ability to use AC can be beneficial in situations where **arc blow** is a concern or when an AC power source is the only option available. This dual capability offers valuable flexibility for various welding setups in critical applications.
**E347-16** electrodes are primarily used for welding **stabilized austenitic stainless steels** such as **Type 321** (titanium stabilized) and **Type 347** (niobium stabilized). It is also suitable for welding unstabilized stainless steels like **Type 304** where the welded component will be exposed to temperatures within the sensitizing range (425°C - 850°C) during service, or where post-weld solution annealing is not feasible. This ensures the integrity of welds in high-temperature corrosive environments.
The weld metal deposited by **E347-16** electrodes typically exhibits excellent mechanical properties. According to AWS A5.4, the minimum requirements are generally similar to other austenitic stainless steel electrodes:
- **Tensile Strength**: 75,000 psi (520 MPa)
- **Yield Strength**: 45,000 psi (310 MPa)
- **Elongation**: 30% (minimum)
These properties indicate good strength, ductility, and toughness, ensuring the weld can withstand operational stresses while maintaining its superior corrosion resistance at elevated temperatures, crucial for reliable stainless steel fabrication.
Generally, **post-weld heat treatment (PWHT)** specifically for **sensitization control** is **not required** for welds made with **E347-16** electrodes. The Niobium stabilization in the electrode effectively prevents carbide precipitation during welding and subsequent exposure to sensitizing temperatures. This eliminates the need for a solution annealing treatment after welding to restore corrosion resistance, simplifying the fabrication process and reducing costs, especially for large stainless steel components used in power and chemical industries.
While both **E347-16** and **E308L-16** are austenitic stainless steel electrodes, **E347-16** is specifically designed for superior performance in **high-temperature service** where the material is exposed to the sensitizing temperature range (425°C to 850°C) for prolonged periods. The Niobium stabilization in E347-16 directly prevents intergranular corrosion in these conditions. **E308L-16**, with its low carbon content, is resistant to sensitization during the welding process, but it may still be susceptible to intergranular corrosion if held in the sensitizing range for extended service. Therefore, for continuous high-temperature applications, E347-16 is the preferred choice for robust stainless steel welds.
Proper storage is essential for **E347-16** electrodes to maintain their welding performance and prevent moisture pickup, which can lead to weld defects like porosity. They should be stored in **dry conditions**, ideally in their original hermetically sealed containers. Once opened, electrodes should be placed in a **heated electrode holding oven (quiver)** at a temperature of approximately 65°C to 150°C (150°F to 300°F). If electrodes have been exposed to humid air for extended periods, they may require re-baking at higher temperatures (e.g., 250-350°C for 1-2 hours) as per manufacturer recommendations to restore their low-hydrogen characteristics, ensuring sound welds in critical stainless steel applications.
While **E347-16** is primarily intended for welding stabilized stainless steels, it can be used for certain dissimilar metal joints, particularly when joining **321 or 347 stainless steel to other stainless steel grades**. However, for joining stainless steel to carbon steel or low-alloy steels, **E309L-16** is generally the more common and recommended choice due to its higher alloy content being better suited to accommodate dilution from the carbon steel side. Always consider the specific service conditions and potential for dilution when selecting an electrode for dissimilar metal welding involving stainless steel.
The typical range of welding current for **E347-16** electrodes varies depending on the electrode diameter and welding position. Common ranges are:
- **2.5 mm (3/32 inch)**: 60 - 85 Amps
- **3.2 mm (1/8 inch)**: 80 - 110 Amps
- **4.0 mm (5/32 inch)**: 100 - 150 Amps
It's always recommended to consult the electrode manufacturer's technical data sheet for the most accurate and optimal current settings to ensure proper penetration, bead appearance, and mechanical properties of the weld, leading to high-quality stainless steel fabrication.
**Niobium (Columbium, Nb)** is the key stabilizing element in **E347-16** weld metal. Its primary role is to prevent **sensitization** by forming stable carbides (niobium carbides) with carbon, thus preventing chromium from forming chromium carbides at the grain boundaries. This preserves the chromium in solid solution, which is essential for maintaining the stainless steel's inherent **corrosion resistance**, especially when the welded component is exposed to operating temperatures in the sensitizing range. This makes E347-16 ideal for demanding service environments.
While not its primary function, the stabilization with **Niobium (Columbium)** in **E347-16** can indirectly contribute to improved **creep resistance** at elevated temperatures. The stable niobium carbides are finely dispersed throughout the weld metal, which can impede dislocation movement and grain boundary sliding, mechanisms associated with creep. This makes E347-16 a more robust choice than unstabilized grades for applications involving sustained stresses at higher temperatures, ensuring the long-term structural integrity of the stainless steel components in industries like power generation and petrochemicals.
Yes, **E347-16** is highly suitable for **high-pressure applications**, particularly in industries such as chemical processing, power generation, and oil and gas, where pressure vessels and piping are common. Its excellent mechanical properties, combined with superior resistance to sensitization and intergranular corrosion at elevated temperatures, ensure the structural integrity and long-term reliability of welds in demanding service conditions. The electrode's ability to maintain its properties in such environments is crucial for safety and operational efficiency of stainless steel pressure-containing equipment.
If **E347-16** electrodes have been exposed to atmospheric moisture, **re-baking** is recommended to restore their low-hydrogen characteristics and ensure optimal weld quality. Typical re-baking procedures involve:
- **Temperature**: Heating electrodes to a temperature range of 250°C to 350°C (482°F to 662°F).
- **Duration**: Holding at this temperature for 1 to 2 hours.
- **Cooling**: Allowing them to cool in a heated oven or transferring directly to a holding oven set at 65°C to 150°C (150°F to 300°F) until use.
Always consult the specific electrode manufacturer's recommendations, as procedures can vary slightly. Proper re-baking is crucial for preventing weld defects like porosity and ensuring sound, critical stainless steel welds.
Similar to other austenitic stainless steel electrodes, the **control of ferrite content** in **E347-16** weld metal is important. While E347 is stabilized, a small, controlled amount of **delta ferrite** (typically 5-10% Ferrite Number, FN) is generally desired in the weld deposit. This ferrite helps to minimize the susceptibility to **hot cracking (solidification cracking)** during welding. Too little ferrite can increase crack sensitivity, while excessively high ferrite could potentially lead to sigma phase formation and embrittlement after prolonged high-temperature exposure. Therefore, manufacturers carefully balance the composition to achieve optimal properties for stainless steel applications.
Multi-pass welding with **E347-16** electrodes in thick sections requires careful attention to maintain weld quality and prevent defects. Key considerations include:
- **Interpass Temperature Control**: Maintaining the interpass temperature below a specified maximum (e.g., 177°C or 350°F) is crucial to control distortion, minimize heat input, and prevent excessive grain growth or unfavorable carbide precipitation.
- **Thorough Interpass Cleaning**: Complete slag removal between each pass is essential to prevent slag inclusions and ensure proper fusion, critical for the integrity of high-temperature stainless steel components.
- **Heat Input Management**: Controlling the heat input per pass helps maintain the desired microstructure and mechanical properties, ensuring the weld performs as intended under service conditions.
Yes, **E347-16** is often specified and used for welding components in **nuclear power plants** and other critical infrastructure. Its superior resistance to **intergranular corrosion** and its stability at elevated temperatures are highly valued in such demanding environments. The stabilization with Niobium helps ensure the long-term integrity and reliability of welds, which is paramount for safety and operational performance in nuclear applications where materials are exposed to specific temperature ranges and potentially corrosive media. Strict quality control and compliance with nuclear codes are always observed when using this electrode in such critical service.
