**Stainless Steel Welding Points and Precautions**
Welding stainless steel requires special attention to detail, as it is a material that is sensitive to heat and oxidation. Here are some key points and precautions to consider during the welding process:
1. Use a power source with a **vertical external characteristic**, and apply **DC electrode positive (DCEP)** when using direct current (the wire is connected to the positive terminal). This ensures better penetration and arc stability.
2. This method is typically suitable for welding **thin plates below 8mm**. It produces a **neat weld bead** with minimal distortion, making it ideal for precision work.
3. The shielding gas used should be **pure argon with a purity of at least 99.99%**. For currents between **50–150A**, the argon flow rate should be **8–10L/min**. For higher currents (150–250A), increase the flow to **12–15L/min** for better protection.
4. The **tungsten electrode** should protrude from the nozzle by **4–5mm** in most cases. In areas with poor shielding, such as **fillet welding**, reduce it to **2–3mm**, while in deep grooves, extend it to **5–6mm**. The distance between the nozzle and the workpiece should generally not exceed **15mm**.
5. To avoid **welding porosity**, ensure the joint area is **clean and free of rust, oil, and contaminants**. Proper preparation significantly improves the quality of the weld.
6. The **arc length** is crucial. When welding ordinary steel, an arc length of **2–4mm** is preferred, but for stainless steel, it should be kept shorter—around **1–3mm**. A longer arc can reduce the shielding effect and lead to defects.
7. To prevent **oxidation on the backside** of a butt weld, the **reverse side must also be protected with shielding gas**. This helps maintain the integrity of the weld.
8. The **angle between the tungsten electrode and the workpiece** should be around **80–85°** for optimal shielding and control. The filler wire should be held at a **small angle (about 10°)** relative to the workpiece surface to ensure smooth feeding.
9. Wind and ventilation are important factors. In **windy environments**, use wind shields or barriers. In indoor settings, ensure proper **ventilation** to prevent gas displacement and improve weld quality.
**MIG Welding of Stainless Steel – Key Points**
1. Use a **flat characteristic power source** and apply **DC electrode negative (DCEN)** for MIG welding (the wire is connected to the positive terminal). This provides a stable arc and good metal transfer.
2. The shielding gas is usually **pure argon (99.99%)** or a mixture of **Ar + 2% O₂** for better arc stability. The gas flow rate should be **20–25L/min** for optimal protection.
3. Arc length is important for **jet transition welding**. Adjust the voltage so that the arc length stays between **4–6mm** for best results.
4. MIG welding is highly sensitive to **wind**, even a slight breeze can cause **porosity**. Ensure the welding area is well-protected, and avoid working in areas where wind speed exceeds **0.5 m/s**.
**Flux-Cored Wire Welding of Stainless Steel – Tips and Precautions**
1. Use a **flat characteristic power source** and apply **DC reverse polarity (DCEP)**. Most COâ‚‚ welders can be used, but adjust the **wire feed tension slightly** to avoid excessive resistance.
2. The shielding gas is typically **carbon dioxide (CO₂)**, with a flow rate of **20–25L/min**.
3. The **distance between the tip and the workpiece** should be **15–25mm** for optimal performance.
4. The **dry extension** (the length of the wire beyond the contact tip) should be about **15mm** for currents below **250A**, and **20–25mm** for higher currents.
For high-quality welding equipment and professional support, you can contact **Guangzhou Zhicheng Hardware Welding Equipment Factory**. They offer a wide range of **gas-shielded welding machines** and expert guidance. Feel free to reach out for more information!
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