Aluminum alloy TIG and MIG welding process analysis: technology comparison, operation points and industry applications
Date: 2025-05-17 Categories: Blog Views: 24
铝合金焊接的挑战与重要性
aluminum 因其轻质、高强度和耐腐蚀性，被广泛应用于汽车、航空航天及船舶制造领域。然而，其高导热性、易氧化特性及热裂纹敏感性，使得焊接工艺面临严峻挑战。以新能源汽车电池托盘为例，焊缝需兼具高强度与气密性，传统工艺难以满足需求，而TIG与MIG焊接技术为此提供了高效解决方案。
Aluminum Features:
small density:: Aluminum alloys have a lower density than steel and copper, about 2.7 g/cm3, so aluminum alloy products are lighter than steel products of the same volume.
high strength: Aluminum alloys have high strength and hardness, which can be significantly improved by heat treatment.
Good conductivity: Aluminum alloys have better electrical conductivity than pure copper and steel and can be used to make conductive materials such as wires and cables.
Good corrosion resistance: The surface of aluminum alloy easily forms a dense oxide film, which has good corrosion resistance.
TIG welding technology in detail
Process principle and equipment configuration
TIG welding (tungsten inert gas shielded welding) uses a non-fused tungsten electrode to form a molten pool under the protection of inert gas (argon or helium). AC TIG welding machine can effectively remove the oxide film (Al₂O₃) on the surface of aluminum alloy through cathodic crushing effect, which is suitable for welding of aluminum alloy of Series 6 (such as 6061) and Series 5 (such as 5052).
Operating points and parameter settings (6061 aluminum alloy as an example)
- Pre-welding treatment:
- Acetone cleaning to remove oil, stainless steel wire brush mechanical sanding oxidation layer (prohibit sandpaper to prevent carbon contamination).
- Welding parameters:
- Current: 80-200A (AC pulse mode, base current accounts for 30%).
- Tungsten electrode: Cerium tungsten electrode (diameter 2.4mm, tip ground at 30° cone angle).
- Protective gas: argon (purity ≥99.99%), flow rate 10-12L/min.
- Choice of filler wire: ER4043 (silicon content 5%, good crack resistance) or ER5356 (magnesium content 5%, high strength).
Strengths and limitations
- dominance: Beautiful, spatter-free weld seams, suitable for thin plates (1-3mm) and precision components (e.g. electronic heat sinks).
- limitations: Slow welding speed (about 0.3m/min) and high labor cost.
MIG welding technology in detail
Process principle and equipment selection
MIG welding (melting electrode inert gas shielded welding) adopts a continuous wire feeding mechanism, which is suitable for welding medium-thick plates. Push-pull wire feeding system can solve the problem of poor wire feeding caused by the softness of aluminum alloy wires (e.g. ER5183). The gas mixture (Ar+He) improves arc stability and reduces porosity.
Operation points and parameter settings (take 5083 aluminum alloy as an example)
- Pre-welding treatment:
- Thick plates (>10mm) need to be preheated to 80-120°C (to reduce the risk of thermal cracking).
- Bevel design: V-bevel (angle 60°-70°), blunt edge 1-2mm.
- Welding parameters:
- Current: 220-260A (double pulse mode, low-frequency pulse to reduce splash).
- Voltage: 24-26V, wire feeding speed 8m/min.
- Protective gas: Ar (80%) + He (20%), flow rate 18-20L/min.
Strengths and limitations
- dominance: High efficiency (speed up to 1.2m/min), suitable for mass production of long weld seams such as automobile chassis.
- limitations: Spatter control is difficult (pulse parameters need to be optimized) and the initial investment in equipment is high (about 500,000 RMB for the robot system).
TIG vs MIG: Process Selection Guide
| comparison term | TIG welding | MIG Welding |
|---|---|---|
| Applicable thickness | 1-6mm (sheet) | 3-25mm (medium and thick plates) |
| Weld quality | High precision, no splash | High efficiency, splash needs to be controlled |
| (manufacturing, production etc) costs | Labor cost as a percentage of 60% | Equipment and Consumables Cost Ratio 70% |
| typical application | Aerospace skins, electronic housings | Ship decks, automotive structural parts |
Welding defect prevention, control and inspection standards
5.1 Solutions to common defects
- stoma: Ensure the purity of the protective gas (argon dew point ≤ -50℃) and thoroughly clean the base metal before welding.
- thermal crack: Select ER5356 wire with high Mg content (Mg/Si>1.5) and control the interlayer temperature <100℃.
- unfused: Increase the current 10%-15% and reduce the welding speed to 0.8m/min (MIG welding).
5.2 Detection methods
- Visual inspection (VT): Detection of cracks and edges on the surface of the weld with reference to ISO 10042.
- X-ray inspection (RT): According to the requirements of AWS D1.2, the diameter of air holes ≤ 1.5mm is qualified.
6. Frequently Asked Questions (FAQ)
Q1: Can TIG welding be used to weld aluminum alloys with DC power?
- NO! DC TIG will not break up the oxide film, AC power must be used.
Q2：How to solve the problem of high spatter in MIG welding?
- Change to double pulse mode, reduce peak current (example: from 300A to 260A) and increase helium ratio to 30%.
Q3: Is heat treatment required after welding?
- 6 series aluminum alloys (such as 6061) need to be solid solution treatment after welding (530 ℃ × 2h water quenching + 180 ℃ × 8h aging) to restore strength.
