3004 aluminum sheets, as a representative Al-Mn-Mg alloy, are widely used in automotive body panels, pressure vessels, marine components, and architectural cladding. Compared with 3003 aluminum sheets, 3004 alloy has higher strength (tensile strength 180-250MPa) and better corrosion resistance, especially in marine salt spray and high-humidity environments. It also has excellent formability, suitable for complex stamping and bending. However, in practical applications such as welding, deep drawing, and long-term outdoor use, specific problems may occur due to its alloy composition and process requirements. Below is a detailed analysis of these common issues, their root causes, targeted solutions, and the core competitiveness of Zhongfu Aluminum’s 3004 high-strength anti-rust aluminum sheets.
I. Common Problems & Root Causes
1. Welding Hot Cracks & Joint Strength Reduction
Welding is a common processing link for 3004 aluminum sheets, but hot cracks and joint strength reduction are prone to occur, affecting structural safety (such as automotive body welding, pressure vessel welding). The main causes are:
Alloy element segregation: Manganese and magnesium elements segregate at grain boundaries during welding, forming low-melting-point phases, leading to hot cracks.
Inappropriate welding parameters: Excessive welding current (exceeding 200A) leads to overheating of the base material, grain coarsening, and joint strength reduction (reduced by 25-35% compared with the base material).
Mismatched welding wire: Using 3003 welding wire for 3004 aluminum sheet welding leads to insufficient alloy element content in the joint and poor strength.
2. Difficulty in Deep Drawing of Complex Shapes
When 3004 aluminum sheets are used for complex deep-drawn parts (such as automotive fuel tanks, pressure vessels), problems such as local cracking and uneven wall thickness are prone to occur. The core influencing factors are:
Inappropriate temper selection: Choosing H18 hard temper (tensile strength ≥230MPa) leads to low ductility (elongation ≤5%) and easy cracking; H14 semi-soft temper may have insufficient strength and cause wrinkling.
Unreasonable mold design: Sharp corners (fillet radius <5mm) or uneven mold surface lead to stress concentration during deep drawing.
Insufficient lubrication: High-strength 3004 aluminum sheets have large friction with molds during deep drawing, and insufficient lubrication leads to uneven material flow.
3. Corrosion of Welding Joints in Marine Environments
Although 3004 aluminum sheets have good anti-rust performance, their welding joints are prone to pitting corrosion or exfoliation corrosion in marine salt spray environments. The main reasons are:
Heat-affected zone vulnerability: The corrosion resistance of the welding heat-affected zone is lower than that of the base material due to grain coarsening.
Lack of post-welding anti-corrosion treatment: No passivation or coating treatment is performed on the welding joint, and the oxide film is incomplete.
Chloride ion erosion: High chloride ion content in marine environments accelerates the corrosion of the joint.
4. Surface Color Difference After Coating
3004 aluminum sheets used in architectural cladding or automotive body panels require coating treatment, but color difference is prone to occur after coating. The main causes are:
Uneven surface roughness: Inconsistent surface roughness (Ra deviation >0.2μm) leads to uneven coating adsorption.
Insufficient surface pretreatment: Oil stains, oxides, or dust on the surface are not thoroughly cleaned, affecting the adhesion of the coating.
Inconsistent coating parameters: Fluctuations in coating thickness (deviation >5μm) or curing temperature lead to color difference.
5. Performance Attenuation in Low-Temperature Environments
When 3004 aluminum sheets are used in low-temperature environments (such as polar marine components, cold storage equipment), their impact toughness may decrease, and brittle fracture may occur. The main factors are:
Grain structure problem: Coarse grain structure of 3004 aluminum sheets leads to poor low-temperature toughness (brittle transition temperature >-30℃).
Residual stress: Unreasonable processing or welding process leaves residual stress, which accumulates in low-temperature environments and causes fracture.
Impurity element influence: Excessive iron or silicon content reduces the low-temperature performance of the alloy.
II. Key Solutions to Mitigate Problems
1. Optimize welding process
Adopt argon arc welding (MIG/TIG) with matching 3004 welding wire, control welding current (150-190A) and speed (5-8 mm/s). After welding, perform low-temperature annealing (300-350℃) to eliminate residual stress and improve joint strength. Conduct post-welding passivation treatment to enhance corrosion resistance.
2. Match temper and optimize forming process
For complex deep drawing, select O-temper 3004 aluminum sheets (elongation ≥20%); for simple forming, choose H14 temper. Optimize mold fillet radius (≥8mm), use high-temperature resistant lubricants (such as molybdenum disulfide-based lubricants), and control stamping speed (15-30 mm/s).
3. Strengthen surface pretreatment and coating
Adopt pickling + anodizing pretreatment to ensure surface cleanliness and uniform roughness (Ra 0.4-0.8μm). Use PVDF coating for marine or outdoor applications (corrosion resistance ≥15 years, color retention ≥12 years). Control coating thickness deviation within ±3μm.
4. Improve low-temperature performance
Adopt refined annealing process (380-420℃) to obtain fine-grain structure, reducing brittle transition temperature to ≤-40℃. For low-temperature application scenarios, conduct low-temperature impact testing (-40℃) to ensure performance meets requirements.
III. Reasons for Choosing Zhongfu Aluminum 3004 High-Strength Anti-Rust Aluminum Sheets
1. High-Strength Alloy & Strict Quality Control
Our 3004 aluminum sheets are made of high-purity aluminum ingots and imported manganese, magnesium ingots, with strict control of chemical composition (Mn:1.0-1.5%, Mg:0.8-1.3%). Tensile strength reaches 190-260MPa, which is 10-15% higher than industry average. All products undergo mechanical property testing, corrosion resistance testing (salt spray test ≥1500 hours), and surface quality inspection, qualified rate 99.9%.
2. Customized Solutions for High-End Scenarios
For automotive body panels, we provide 3004 aluminum sheets with thickness 1.0-2.5mm and electrophoretic coating; for pressure vessels, we offer O-temper 3004 sheets with thickness 2.0-6.0mm and ultrasonic flaw detection; for marine components, we provide 3004 aluminum sheets with PVDF coating. Common specifications: thickness 0.5-8.0mm, width 1000-2200mm, support non-standard customization.
3. Professional Technical Support for High-Difficulty Processing
Our technical team with 22 years of aluminum alloy processing experience provides one-stop services for high-difficulty scenarios, including welding process design, complex forming parameter matching, and low-temperature performance optimization. We have helped 900+ automotive, marine, and architectural customers solve processing and corrosion problems.
4. Strong Production Capacity & Reliable Supply Chain
Annual production capacity of 3004 series aluminum sheets reaches 200,000 tons, with sufficient inventory of common specifications. Cooperate with major ports to provide flexible international logistics solutions (sea, air, land transport), and provide customs clearance documents (certificate of origin, material test report) to ensure smooth import and export. On-time delivery rate 99.6%.
5. Factory-Direct Pricing & Global High-End Recognition
Eliminate intermediate agents, helping customers save 10-18% procurement costs. Products are exported to Europe, North America, and Southeast Asia, serving 250+ distributors and 4,500+ end customers. Hold ISO9001, IATF16949 (automotive industry), and SGS corrosion resistance certifications, customer repurchase rate 91%.
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