In liquid cooling plate projects, there’s a question I’ve heard many times from clients: “Will using the H14 or H16 temper for 3003 material in an annealed state make it stronger than the H0 temper?” This idea isn’t surprising. The strength data for H14 and H16 is indeed higher than that of H0, so many people assume that the harder the material, the more stable the structure of the finished product will be, especially in applications like new energy vehicle battery packs and energy storage systems where the liquid cooling plate needs to withstand mechanical stress. But in reality, things are not so simple.
During production, the material goes through various processing steps, and one process is almost unavoidable—brazing. The high temperature involved not only firmly bonds the upper and lower plates of the liquid cooling plate together, but also changes the internal structure of the material, which greatly reduces the strength difference between H14/H16 and H0 in the final product. That’s why many people are surprised when they see the final test results—H14 and H16 don’t retain the imagined strength advantage. Next, I want to talk about the real reason behind this.
Before discussing the strength differences, let’s first take a look at the characteristics of 3003 liquid cooling plates. It is an aluminum-manganese rust-proof alloy, mainly composed of aluminum (Al) and a small amount of manganese (Mn). This composition gives it both excellent corrosion resistance and good workability, making it suitable for various forming methods such as stamping, bending, and welding, while being less prone to cracking or significant deformation. Its thermal conductivity is also quite good—although not as high as pure aluminum, it is still among the best compared to most alloy materials—making it very suitable for scenarios that require efficient heat exchange.
Thanks to these advantages, 3003 liquid cooling plates are widely used in fields such as electric vehicles and energy storage systems, where thermal management requirements are high. In these scenarios, they not only provide stable structural support but also help quickly transfer and dissipate excess heat, ensuring the system can operate safely over long periods of time.
After understanding the material properties and application scenarios of 3003 liquid cooling plates, the next topic to discuss is a question often raised during the material selection stage—the temper state. For 3003 liquid cooling plates, the most common tempers are H14, H16, and H0. They are not different materials, but rather the same alloy grade that exhibits different mechanical properties after undergoing different processing methods or heat treatments.
● H14: Half-hard temper, in which the material is hardened through cold working, giving it moderate strength while still maintaining good ductility.
● H16: Higher hardness temper, with a greater degree of cold working, resulting in higher strength than H14, but relatively lower ductility.
● H0: Fully annealed temper, where the material is heated and slowly cooled to release internal stresses, giving it the lowest hardness but the best ductility and workability.
From the material data, both the yield strength and tensile strength of H14 and H16 are significantly higher than those of H0, which is why many people tend to prefer them when choosing materials. However, these tempers only provide an advantage in the initial stage. During the manufacturing process of liquid cooling plates—especially after subsequent high-temperature steps—this difference may be weakened or even altered. As for why this happens, we need to start with the brazing process.
In the production process of liquid cooling plates, brazing is an unavoidable step. Its role is not only to join the upper and lower layers of the plate together, but also to form sealed and reliable cooling channels inside, ensuring that the coolant can circulate smoothly along the designed path without leakage or blockage—this directly affects the reliability and lifespan of the entire heat exchange system.
The problem is that brazing is not a gentle process. It needs to be carried out at a high temperature of around 600℃ to 700℃, which is far above the recrystallization temperature of aluminum alloys (about 250℃ to 300℃). For tempers like H14 and H16, which rely on cold working to improve strength, high temperature brings two key changes:
● Work hardening is weakened
In a high-temperature environment, the dislocation structures in H14 and H16 caused by cold working are reset, and the hardened state of the material gradually disappears.
● Grain structure is readjusted
High temperature promotes recrystallization in the metal, causing the grains to rearrange and grow while releasing internal stresses.
Put together, these two changes essentially amount to a complete annealing process. As a result, whether it starts as H14 or H16, after brazing its mechanical properties will approach those of the H0 state—strength decreases, while ductility increases.
I’ve encountered a very typical example: a client insisted on using H16 to improve the rigidity of the liquid cooling plate. However, after brazing and final testing, the difference in yield strength compared with H0 was almost negligible, meaning the two performed nearly the same in actual use. XD THERMAL’s lab verification showed similar results, where the post-brazing strength of H14 and H16 converged towards H0. This highlights why relying solely on handbook data without considering process effects can mislead design decisions
Therefore, understanding the impact of brazing on material temper is not just a technical detail for materials engineers—it’s also a key factor to be considered at the design stage. It affects not only performance, but also the pace of product development and cost control.
● Optimize structural design
Improve overall rigidity by adding reinforcement ribs, support ribs, or similar features to the plate, instead of relying solely on material hardness.
● Adjust plate thickness
Moderately increasing thickness can enhance load-bearing capacity and resistance to deformation, but weight and cost must also be taken into account.
● Evaluate secondary heat treatment
Adding an appropriate heat treatment process after brazing can partially restore material strength, but it needs to be balanced against cost and production efficiency.
● Consider special process alternatives
For rare cases where extremely high strength is required, low-temperature brazing or mechanical joining can be considered, though these typically increase manufacturing difficulty and cost.
From my experience, material selection and process design must go hand in hand—especially for liquid cooling plates, which need to provide both heat transfer and load-bearing capabilities. Optimizing only one aspect can easily cause problems in the other. Only by considering changes in material temper from the very beginning can you avoid repeated modifications later, saving both development time and cost.
In short, for 3003 liquid cooling plates, whether they start as H14 or H16, once they undergo high-temperature brazing, the material temper will gradually approach H0, with strength differences significantly reduced and ductility improved. This results from the weakening of work hardening and the readjustment of grain structure. For design and material selection, this serves as a reminder that we cannot look only at material parameters—we must evaluate them together with the production process. At XD THERMAL, we emphasise that recognising temper changes early allows engineers to reduce design iterations, save cost, and make full use of 3003’s corrosion resistance, workability, and thermal conductivity in EV battery packs and energy storage systems
