Many procurement professionals have misconceptions about the "soft temper" of aluminum circles, often confusing semi-soft materials annealed at low temperatures with the standard O temper, ultimately leading to problems such as deep drawing cracking and fluctuating forming yield. As the core supply state for deep drawn aluminum circles, the standard O temper has a clear definition of heat treatment and performance boundaries. In the global cookware industry, O temper aluminum circles account for over 60% of deep-drawn blanks.
The essence of the O temper is a fully recrystallized annealed state. According to the ASTM B209 standard definition, O temper aluminum circle materials need to undergo a constant-temperature holding and slow cooling process above the recrystallization temperature to completely eliminate cold-rolling work hardening and residual internal stress, allowing the internal grains to fully recrystallize and form a uniform equiaxed grain structure. This is fundamentally different from what is commonly referred to in the industry as the "soft temper": Semi-soft aluminum circle materials obtained by some manufacturers through low-temperature short-time annealing have insufficient internal stress release, resulting in batch-to-batch elongation fluctuations exceeding 8%, making them only suitable for shallow drawing applications. Standard soft O temper aluminum circles, require a complete heating-holding-slow cooling process, ensuring uniform performance across the entire roll. This is a mandatory selection requirement for deep drawing and complex spinning processes.
From a quantitative performance perspective, different grades of O temper aluminum circles have varying strengths in their forming capabilities. Mass production measured parameters all conform to international standards:
1050-O aluminum circles belong to the high-purity aluminum system, with measured tensile strength of 65~95MPa, yield strength of 25~40MPa, elongation after fracture at a gauge length of 50mm ≥30%, and cupping test IE value ≥10.8mm. It is the grade with the best plasticity among commercially available aluminum discs, suitable for extreme deep drawing applications with a draw ratio >2.5, such as tall milk pots and deep soup pot blanks;
1100-O aluminum circles contain trace amounts of copper, measured... With tensile strength of 75~105MPa, yield strength of 35~50MPa, elongation after fracture ≥28%, and cupping value ≥10mm, it offers a balance of strength and formability, making it the mainstream choice for general deep drawing.
3003-O aluminum circles is an aluminum-manganese alloy system with measured tensile strength of 95~130MPa, yield strength of 40~65MPa, elongation after fracture ≥25%, and cupping value ≥9.5mm. Its strength is approximately 40% higher than pure aluminum, and it exhibits superior resistance to weak acid corrosion, making it suitable for deep-drawn products requiring high strength, such as those used in brazing and high-pressure cookware.
It is important to clarify that the O temper is not suitable for all scenarios, and there are clear performance boundaries for selection. Scenarios where the O temper must be used include: deep drawing with a draw ratio ≥2.0, multi-pass drawing processes, complex irregular spinning, and products requiring high surface finish after forming (such as mirror reflectors). In these scenarios, the O temper can effectively reduce the defect rate of sidewall cracking and mouth wrinkling. For shallow-drawn/flat-stamped components (drawing ratio < 1.5) and structural parts requiring high rigidity, the O-temper is not recommended. In this case, the material is prone to wrinkling during stamping and deformation of the finished product. The H12/H14 semi-hard temper is a more cost-effective option.
For export-grade products, the core of quality control for O temper aluminum circles lies in batch consistency. Haomei Aluminum uses a continuous annealing furnace, controlling furnace temperature deviation within ±5℃. The finished product grain size is stable at ASTM 6~8, with elongation fluctuations within the same batch ≤3%. It is compatible with fully automated high-speed stamping production lines, requiring no frequent process parameter adjustments, and maintaining a stable overall yield of over 99% in mass production. Currently, we supply a full range of O temper aluminum circles with thicknesses from 0.3mm to 6.0mm and diameters from 100mm to 1200mm. All grades meet ASTM B209 standards and food contact safety requirements, and are packaged with special protective packaging for ocean shipping. Tailored temper adjustment solutions can be provided based on the customer's drawing process