Stock code: 601677
Stock code: 601677
When sourcing aluminum sheets, many focus solely on the alloy grade. However, the temper is what truly determines performance in stamping and deep drawing. In fact, selecting the right aluminum sheet temper for press forming is the most critical step—yet it is often overlooked. The same alloy, say 5052, can be deep‑drawn into complex shapes in O‑temper, but in H38 it would crack immediately on the press. Choosing the wrong temper undermines even the best alloy choice.
Aluminum sheet tempers fall into three main categories:
– O‑temper (fully annealed) – lowest strength, maximum ductility. Ideal for stretching, deep drawing, and complex forming.
– H‑temper (strain‑hardened) – strength increased by cold rolling. Used for non‑heat‑treatable alloys (1xxx, 3xxx, 5xxx series). The number after H indicates the degree of hardening.
– T‑temper (heat‑treated) – strengthened by solution treatment and aging. Used for heat‑treatable alloys (2xxx, 6xxx, 7xxx series).
Selecting the right temper is essentially about finding the optimal balance among strength, hardness, and ductility for the specific forming operation.
If a part requires deep drawing, tight bending, or multi‑step forming, O‑temper is the most reliable option.
Take 5052‑O: its elongation can exceed 25%. The same alloy in H32 or H34 has far lower elongation. Higher elongation means the material can undergo greater deformation without cracking.
Two additional advantages of O‑temper are often underestimated:
– Minimal springback – low yield strength means less elastic recovery, so parts maintain dimensional accuracy after forming.
– Work‑hardening gain – for alloys like 5052, the material naturally work‑hardens during forming, so critical areas can reach strengths comparable to H32 or H34 after deformation. In other words, form soft, use hard – this is the unique value of O‑temper.
For conventional stamping (not deep drawing), H‑temper offers a more economical choice. H14 is the most common “workhorse” for general forming.
Take 3003‑H14: tensile strength is about 145 MPa, with elongation ranging from 8% to 16%. The material has moderate cold work, retaining sufficient ductility while providing useful strength – it bends and stamps without cracking.
Both are half‑hard, but H24 receives a stabilizing anneal that reduces internal stress and improves formability. For parts with smaller bend radii or more complex shapes, H24 is the better choice.
A word of caution: H18 (full hard) has elongation of only 4% to 10% and is not suitable for press forming. If the finished part needs high strength, the correct approach is to form in O‑temper and then heat‑treat to the desired hardness, rather than forcing the forming with a hard temper.
T‑tempers are used for 2xxx, 6xxx, and 7xxx series alloys. The key point is that T6 is not suitable for direct forming.
6061‑T6 has high strength but poor formability. If the final part requires T6 properties, the conventional route is to form in O‑temper and then heat‑treat to T6.
For ultra‑high‑strength 7xxx alloys (e.g., 7075), cold stamping is nearly impossible. The industry solution is W‑temper forming – solution‑treat the material, form it immediately (while it is softest), and then age‑harden it afterwards.
Cracking – root cause: insufficient ductility. Deep‑drawn parts must use O‑temper; general stamping should use H14 rather than H18.
Springback – harder tempers cause more springback. O‑temper has negligible springback; if hard tempers must be used, die compensation is essential.
Orange peel – surface roughening during forming, caused by coarse grain structure. Excessive annealing temperature or time can lead to large grains. Choosing fine‑grain O‑temper products helps avoid this.
Earing – wavy edges at the cup rim, caused by rolling texture anisotropy. O‑temper annealing can partially reduce the texture and minimise earing.
|
Forming Scenario |
Recommended Temper |
Reason |
|
Deep drawing, complex 3D shapes |
O‑temper |
Highest ductility, minimal springback |
|
General stamping, shallow forming |
H14 or H24 |
Best balance of strength and formability |
|
Final T6 strength required |
Form in O → then heat‑treat |
Avoid cracking by forming before hardening |
|
7xxx ultra‑high‑strength alloys |
W‑temper |
Form while soft, age after hardening |
The temper is the most overlooked yet most critical factor in selecting aluminum sheet for press operations. Getting it right means smooth production and low scrap rates; getting it wrong invites cracking, springback, and surface defects. This guide should help steer the choice in the right direction.
Choosing the correct aluminum sheet temper for press forming ultimately depends on part geometry, required final strength, and production efficiency – use the guidelines above to make a confident decision.
Q: Which temper is best for deep drawing?
A: O‑temper (fully annealed) – it offers the highest elongation and virtually no springback.
Q: Can 3003‑H18 be used for stamping?
A: No – H18 is fully hard, has low elongation, and will crack under stamping stress.
Q: H14 or H24 for stamping – which is preferable?
A: H24 has better formability and lower internal stress; choose H24 for complex shapes.
Q: Does O‑temper provide enough final strength for finished parts?
A: Yes – it work‑hardens during forming, gaining significant strength in critical areas.
Q: How can springback be controlled in stamped aluminum?
A: Use O‑temper for minimal springback; if hard tempers are used, compensate in the die design.
Q: What causes orange peel and how to avoid it?
A: Coarse grain structure causes orange peel – select fine‑grain O‑temper products to prevent it.
For reliable supply of O‑temper, H‑temper, and T‑temper aluminum sheets for your press forming needs, Mingtai Aluminum offers comprehensive temper options with stable quality and consistent mechanical properties.
