Stop cracking: pick aluminum sheet temper for deep drawing

When it comes to aluminum sheet temper for deep drawing, the decision you make at the very beginning often determines whether your parts form smoothly or end up as scrap. Deep drawing pushes material through severe tensile and compressive stresses, and many manufacturers focus on die design or lubrication while overlooking the fundamental question: have you chosen the right temper?

Take a common alloy like 5052. The elongation of the O temper can be more than double that of H32. That difference directly translates into successful forming versus frequent cracking.

O Temper vs. H Temper – What’s the Difference?

O Temper (Fully Annealed)  

– What it is: The sheet is heated and slowly cooled to remove internal stress and soften the grain.  

– Performance: Lowest strength, highest plasticity – excellent for deep drawing, bending, flanging, and stretching.  

– Best use: Any operation that requires large, complex deformation.

H Temper (Strain‑Hardened)  

– What it is: Strengthened by cold working after annealing.  

– Sub‑grades: H12, H14, H16, H18 – the higher the number, the stronger but less ductile the material.  

– Best use: Applications where strength matters more than formability, such as flat panels or shallow bends.

Quick analogy:  

– O temper = soft dough – easy to shape without breaking.  

– H temper = baked bread – firm, but bends too far and it cracks.

Why O Temper Is the Default Choice for Deep Drawing

• Elongation: O temper offers substantially higher elongation than H grades (e.g., 5052‑O >20%, while H32/H34 are much lower). This extra ductility gives the safety margin needed for complex draws without tearing.
• Springback control: Lower yield strength in O temper means less elastic recovery after forming, so your parts hold dimensions more accurately – no costly die compensation required.
• Work‑hardening bonus: During drawing, O temper naturally hardens in high‑strain zones (corners, sidewalls) while staying softer elsewhere. This “on‑demand” strengthening gives finished parts added robustness, often reaching strength levels close to H32/H34.

Which Alloy and O Temper to Choose?

Different alloy families each have their own O‑temper characteristics:

– 1xxx series (1050, 1060, 1100) – high purity and formability. Best for parts that require extreme shaping but little strength, such as lamp reflectors and cookware.

– 3xxx series (3003) – aluminium‑manganese alloy with excellent deep‑drawing performance and good corrosion resistance. 3003‑O is a classic choice for cookware and containers because of its outstanding elongation.

– 5xxx series (5052, 5754) – aluminium‑magnesium alloys that offer higher strength than 1xxx and 3xxx while still maintaining good drawability. 5754‑O guarantees elongation of at least 25%. These are ideal for automotive fuel tanks, marine components, and electronic enclosures where both corrosion resistance and moderate strength are needed.

Quick selection guide:

– Deep draws with complex shapes → choose O temper.

– Moderate forming with some stiffness required → consider H24 (better elongation than H14 at the same strength level).

– Shallow draws or bending with high strength needs → H14 may work.

Common Problems in Deep Drawing and Their Relation to Temper

• Cracking – the most common failure, caused by insufficient elongation. O temper greatly reduces this risk. If cracking still occurs, check your die radius (≥3t), clearance (1.1–1.2t), and lubrication before blaming the material.
• Wrinkling – O temper is theoretically more prone to flange wrinkles, but proper blankholder pressure controls it well. H temper wrinkles less but cracks more easily; in practice, O temper remains the safer overall choice.
• Multi‑stage drawing – when a very high draw ratio requires multiple draws, even O temper work‑hardens after the first stage. Plan intermediate annealing (340–360°C for 1–2 hours) to restore formability.

Key Considerations When Purchasing Deep‑Drawing Sheet

• Define your forming process first – know your draw ratio, number of stages, and tooling. These dictate the elongation you actually need.
• Prioritise formability over strength – in deep drawing, “softer” is better. Low strength in O temper is a feature, not a flaw.
• Demand consistent elongation batch‑to‑batch – even with the same O‑temper label, values vary across suppliers. Always request mechanical test reports and track stability.
• Use YS/T 688‑2024 as a benchmark – this Chinese standard covers deep‑drawing sheet for fins, containers, shells, etc. Refer to it when qualifying new sources.
• Evaluate total cost, not just unit price – O temper may cost slightly more upfront, but it lowers scrap, extends die life, and often skips intermediate annealing – savings that usually outweigh the extra material cost.

Choosing the right aluminum sheet temper for deep drawing can make or break your production efficiency and part quality. If you’re looking for a reliable source of O‑temper sheet in 1xxx, 3xxx, or 5xxx series that meets YS/T 688 and delivers consistent mechanical properties across every batch, Mingtai Aluminum offers a full range with full technical support – feel free to request data sheets and samples.

FAQ

Q1: Is O temper always required for deep drawing?  

Not always, but for draw ratios above 2.0 it’s the default; H tempers are only suitable for shallow draws or bending.

Q2: Won’t O‑temper parts be too weak in service?  

No – the work‑hardening that occurs during forming strengthens critical areas significantly.

Q3: Which is better for deep drawing: 3003‑O or 5052‑O?  

Both perform well; 3003‑O offers higher elongation and easier forming, while 5052‑O gives higher strength and better corrosion resistance.

Q4: What’s the difference between H14 and H24?  

H24 is partially annealed after cold working – it has the same strength as H14 but with better elongation, making it slightly more drawable.

Q5: If I get cracking, is the temper always the culprit?  

Not necessarily – check die radius, clearance, lubrication, and blankholder pressure before blaming the material.

Q6: Can I use O temper for multiple draws without annealing?  

Only for very light reductions; for high total draw ratios, intermediate annealing is usually required to restore formability.