📚 Yield Strength
Rp and Rp0.2
💪 How strong is the Titan?
Knowledge: The Yield Strength Rp
The Stress-Strain-Diagram shows the strain (ε) of the material on the x-axis, while the y-axis represents the stress (σ) applied to the material.
The value Rp is also known as the Yield Strength. Rp is defined as the point at which plastic deformation begins. Thus, Rp indicates the stress (= force per area) required to produce permanent deformation in the material.
Rp is an indicator of the material's ability to withstand stress without permanent deformation. A higher Rp value means that the material is more resistant to deformation and has greater strength.
Permanent deformation would destroy the Steel Wallet.
Rp0.2 = central material characteristic
When determining Rp0.2, the stress is measured at a specific point on the stress-strain curve, precisely at a plastic deformation (=strain) of 0.2%.
Rp0.2 is ultimately easier to determine than Rp, which is why the latter is used as a reference value in science.
Structure & Material
The base body and seed discs are made of AISI 316Ti (Titanium Alloy Stainless Steel, 1.4571) for optimal protection.
The inner housing is 100% titanium grade 5 (3.7165). It serves as a second, extremely strong protective shield for your seed.
Quality instead of Marketing
Sad but true, the "finest stainless steel" is often just a standard AISI 304 (1.4301) stainless steel. Titanium is usually Grade 2 (3.7035). With titanium, the choice of this weaker variant is obvious, since you would have to use more than 4 times the force to hammer your seed into titanium Grade 5 (compared to the stainless steels AISI 304, 316 or 316Ti). At most, Roman Reher can manage that...
Stainless steel: 316Ti is the clear favorite
Unfortunately, the vast majority of steel wallets and backup solutions are made of 304 stainless steel....
Titanium Grade 5 is undisputed
Since Titanium Grade 2 is much cheaper, this material is often used. But not in our case!
Fun Fact: Titanium Grade 5 was originally developed for aerospace applications. 🚀
Titan Wallet: Very Good to Excellent!
Titanium has excellent resistance to corrosion and acids and is one of the few materials considered resistant to seawater.
AISI 304 is largely adequate for normal use. 304 is sensitive to chlorides and acids and is also somewhat susceptible in saline media.
Steels 316 and 316Ti are less sensitive in this respect. For example, they are even resistant to sulfuric acid (1%).
PREN = Pitting Resistance Equivalent Number
(which can be traced in the corresponding standard and/or in the following sources).
Do your own research!
The information on this page is mainly derived from the following sources
Bargel, H.-J. (Hrsg.) 2022 - Werkstoffkunde
Wittel, Spura et al. 2021 - Roloff/Matek Maschinenelemente
Deutsche Edelstahlwerke (https://www.dew-stahl.com/)
Zapp AG (https://www.zapp.com/)
TEAM EDELSTAHL GmbH & Co. KG (https://www.teamedelstahl.de/)
Walter Kaiser Gmbh (https://www.beizgmbh.de/documents/Edelstahlvertraeglichkeit.pdf)