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Hydrogen Embrittlement in Plating



An ongoing series about hydrogen embrittlement in plating, from 1996 to 2014 --

(1996)

Q. We have had problems with a metal clip, and it is said to be due to "hydrogen embrittlement". What is hydrogen embrittlement, and how do you avoid/alleviate it?

Michael Marshall
Indianapolis, Indiana


(1996)

A. Hydrogen embrittlement is a phenomenon that affects high-strength steel. Hydrogen--often from pickling or plating--invades the grain structure of a high strength steel, making it brittle and subject to catastrophic failure.

The best approach is to avoid or minimize processes that cause hydrogen embrittlement. The second best approach is to bake the parts to drive the hydrogen out, preferably very soon after plating. Some people feel that some degree of permanent damage occurs during the time between plating and baking, and that it is thus vital to bake immediately. Others feel that the old standard "bake within 24 hours" is sufficient. ASTM Committee B-8 spent a lot of time on this problem, so I think their specs are highly trustable.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(1996)

A. Michael: We have had some experience with the phenomena of hydrogen embrittlement. A good reference book is "Hydrogen Embrittlement and Stress Corrosion Cracking" [link is to info about book at Amazon] by Gibala and Hehemann (ASM Publication). It is quite detailed and informative.

Brian Cardwell
Ford Motor Company



(1996)

Q. I am looking for articles on "Hydrogen Embrittlement" in the plating process.

John M. Grimes
Cutler-Hammer


(1996)

A. Over the years, the Airline Plating Forum has had several papers given on the subject. Available thru the AESF bookstore. There is a stray article in the plating magazines. Seems to me that the big book ASM library had some information on it. You might check the index for the various Sur-Fin abstracts. These probably will be more technical and less practical.

James Watts
- Navarre, Florida



Do corners and high current density areas get more hydrogen embrittlement?

(1998)

Q. During plating, are the corners of objects preferential sites for hydrogen and therefore more susceptible to hydrogen embrittlement?

David M. French
Charlotte North Carolina


(1998)

A. Yes and no. Since the edges (corners) are high current density areas, they plate much faster, so more H2 is generated there, so it will be a little more prone to problems there. In high stress deposits, the additional thickness puts the parent material under a lot more stress, so will tend to have more problems there.

A stress riser like a tiny cut from a razor blade in masking on a high tensile strength part will be much more prone to fail. Inadequate radius at flanges are very prone to failure. The end result is a failed part, but the root causes are wildly different.

James Watts
- Navarre, Florida

hydrogen book
Current Solutions to Hydrogen Problems in Steels

Interrante & Pressouyre


(1998)

A. The amount of Hydrogen Embrittlement absorbed during electroplating is related to the current density on the cathode surface of the article being plated. Higher current density areas will evolve more Hydrogen gas and therefore the potential for embrittlement is higher. Edges will normally be higher current density than flat surfaces. Edges that are on bottom rows of racks will most likely have higher levels of absorbed Hydrogen. In most cases of electroplating, edges will have higher preferential sites for Hydrogen Embrittlement. Maintaining optimum electroplating efficiencies and additions of wetting agents are variables that can help reduce embrittlement by Hydrogen gas.

Bill Boatright
Morrisville, North Carolina


(1998)

A. Higher current densities will definitely produce more hydrogen per metal deposited, but...

Some processes (for sure low embrittlement cadmium, but maybe some others too?) use high current densities on purpose in order to produce porous plating that allows for easy hydrogen molecule escape during the subsequent bake.

In general I do not think that areas where most of the hydrogen is absorbed would suffer higher danger of embrittlement: metal is a "transparent" media for protons (hydrogen atom's nucleus), therefore the bulk of the plated part (even the non-plated part of it, if masked) will be equally prone to embrittlement.

The question remaining - where it may break? - in the point of maximum stress, even if that portion of the part is not plated.

This is just an opinion...

Max Stein
captive metal finisher - Montreal, Québec, Canada



How to identify hydrogen embrittlement?

(1998)

Q. How does one determine if breakage is caused by hydrogen embrittlement? We have parts which are made from 1074 steel, .0135" thick, which has been formed (into a question mark shape) and then heat treated to RC 44-47. These parts can be bent without breakage. However after zinc and bake, they do break when bent pretty far back in the large radius area.

How does one determine if the breakage is caused by hydrogen embrittlement? Or is it possible that just by plating these parts, they will become more prone towards breakage?

Andrew Roberts
springs - San Leandro, California


(1998)

A. If you had access to a Scanning Electron Microscope (SEM) and someone with experience in analyzing for Hydrogen Contamination it could be possible to show breakage was caused by Hydrogen Embrittlement.

However, since you say the parts are not breaking before plating but are breaking after, the possibility is strong that hydrogen embrittlement is occurring in your parts. Have you baked the parts for hydrogen embrittlement relief immediately after plating and before bending.

Greg Haataja
helicopters - Fort Worth, Texas


(1998)

A. You have about as close to 100% probability as you will ever get that you have a classic H2 embrittlement problem.

Bake as soon as possible after plating. The longer the H2 is trapped between the plate and the base metal, the further it penetrates the steel and the harder it is to get out.

Do not flex the parts even a tiny bit taking them off the rack!

If you are baking, get there sooner and bake longer or at a higher temp.

After bake a very quick dip in a mild (weak) nitric solution will activate it enough that it will take a chromate. Consult your chromate vendor and do some trial and error testing to see how weak you can get by with.

James Watts
- Navarre, Florida


(1998)

A. A considerable amount of work on hydrogen embrittlement has been conducted and published in the literature. Some important work was done and published by scientists at the Naval Air Warfare Center. The bottom line is: it is nearly impossible to remove all of the hydrogen that has been introduced, using common baking methods. Once the damage is done, it can be reduced to some extent. The amount of damage and reduction will depend on dozens of variables such as the part, its material, coating, process, amount of hydrogen generated and absorbed and combinations thereof. Relief is likely to be inconsistent. This inconsistency could be reduced by porosity in the coatings.

Mandar Sunthankar
- Fort Collins, Colorado


(1998)

A. Hydrogen embrittlement is typically manifested as "delayed fracture" at static stresses, which would be contrary to immediate failure during bending. Your parts, however, are quite susceptible to hydrogen damage and may be cracked during plating if the parts have sufficient residual stress from heat treating. A static load test with less deflection than will cause immediate cracking could be definitive.

Another alternative to consider is possible embrittlement due to the baking process. This material is susceptible to tempered martensite embrittlement, usually from exposure to temperatures from 400 °F to 700 °F. I would avoid baking at temperatures above 375 °F.

I agree with Mr. Sunthankar that baking is not 100% effective. The extreme susceptibility of this material to cracking by hydrogen embrittlement would suggest to me that an alternative corrosion protection would be prudent.

hanke Larry Hanke
  materials testing laboratory
Minneapolis, Minnesota




Alternatives to Plating to Minimize Hydrogen Embrittlement

(1998)

A. If hydrogen embrittlement is of concern, you may want to consider mechanical plating and/or galvanizing. I have been involved in many studies comparing zinc electroplating, hot dip galvanizing and mechanical -- and mechanical does not impart hydrogen.

Ray Delorey
Cambridge, Ontario, Canada

adv.  


(2006)

A. One of the best systems for coating that do not have any hydrogen embrittlement is the Thermal Diffusion zinc coating system. Google it and you'll learn quite a bit.

Dorian Shifman
- Charlotte, North Carolina

----
Ed. note: Thermal Diffusion is an upgrade to the older process called Sherardizing, which is discussed in many threads on this site.




Can heat treating cause hydrogen embrittlement?

(1999)

Q. Could you please let me know if there is a possibility for hydrogen embrittlement to be introduced into my parts during this heat treat process:

Material: .012" +/- .001" C1050 Annealed Spring Steel
Heat Treat: Austempered to Spring Temper Rc 38-42

I know that I have a hydrogen embrittlement problem induced by my plater due to improperly calibrated ovens for baking off the hydrogen. I need to know if there are other ways for hydrogen to be introduced into my stampings.

Adam Rubin
- Brockton, Massachusetts


(1999)

A. I really do not want to get in the middle of an argument, but will express my opinion.

I have never heard of hydrogen embrittlement being caused by bake.

Uncalibrated ovens probably did not contribute much to hydrogen embrittlement of your parts because bake relief is really wide open as a function of time and temperature. 375 °F for 4 hours is + or - 25 °F as a common relief.

Two things cause more grief than a few degrees difference.

1. The time between plating and into the oven. For spring material is should be as soon as possible. The 4 hour book value is really too long. The longer you wait, the harder it is to get out and the more damage has been done.

2. The acid activation or etch contributes more to embrittlement than the plating process does. For spring steel I would use periodic reverse or anodic electroclean followed by a very short, say 10 second dip in a conventional hydrochloric or sulfuric acid tank. I have done cyanide and acid cad without a failure of notch bar testing at some very high tensile strengths.

If these are not critical parts to safety, I would bake them for 24 hours, possibly 48 for better reliability and use them. These are tiny parts that can be nicely run in a lab oven at a very low cost with a decent recovery of the unbroken parts.

James Watts
- Navarre, Florida


(1999)

A. To answer part of Mr. Rubin's question (can austempering cause hydrogen embrittlement?):

I would say no, especially if the austenitizing (not the quenching) is done in salt. If the austenitizing is done in an atmosphere furnace (typically endothermic gas at 40% H2), then some hydrogen is absorbed by the metal. I suppose one could argue that this might cause HE. I know it can cause delayed quench cracking in parts quenched in media such as water or oil, and although hydrogen levels are probably much lower than in "classical" HE, it could be called hydrogen embrittlement. I doubt very much that cracking would occur in an austempered part because the residual stresses and residual hydrogen levels are typically much lower due to the gentler quench rates and the residence time at the austempering temperature.

In other words, it's hard to imagine austempering causing HE, and I think most metallurgists and heat treaters would agree they've never identified such an occurrence or even suspected the possibility.

John Ullman



Does GM4345M Phos & Oil require de-embrittlement?

(1999)

Q. When 1050 material is processed to an Rc range of 40 - 48 and subsequently plated to GM4345M commonly referred to as Phos & Oil, what is the correct practice with respect to baking this porous plating?

Is baking necessary, or is delay in use after plating sufficient to allow the H2 to outgas? If delay is sufficient, what is the recommended period of time for delay?

What role does acid concentration play in processing the Phos & Oil in the cleaning tanks? A common standard seems to be to stay under 30%, is there a recommended concentration? What is it?, and is there a maximum that should not be exceeded to avoid hydrogen embrittlement?

Time in the tank is controlled to under 10 minutes.

L.C. Wood
Detroit, Michigan


(1999)

A. Bake- You have to conform to what the spec calls out.

Many specs would not call for a bake at an Rc of 40. I do not remember doing one at Rc48, so cannot be of any help there.

Many people will not refer to phosphate as plating, since you are not depositing a metal or alloy.

Acid normally will be as strong as you need to do the job, but no stronger. Time is a tradeoff with acid strength. You have to specify the acid when you talk %'s. Sulfuric acid has two H's, so is basically twice as strong as hydrochloric (muriatic). Some people use mixed acids.

Acid etch is a major contributor to hydrogen embrittlement, so any etch should be the minimum to get by on hard parts.

If you use an acid etch, You really need to use a proprietary Ti compound additive to the last rinse prior to phosphate. Normally, you will get a lousy phosphate if you do not. I have heard of a very few that have avoided it.

James Watts
- Navarre, Florida



(1999)

Q. We manufacture and electroplate automotive safety hardware and are very well aware of the "critical" stress relieving requirements. However, we also have a large volume of parts which are sub-contracted for E-coating that do not specify any stress relieving requirements. My question is: "If similar pre-cleaning cycles and materials are used for the cleaning of steel parts for electroplating and/or e-coating, how come e-coated parts do not specify a post bake to relieve any possibility of hydrogen embrittlement during the processing"? It appears to me that the temperature and time required to bake the paint film is not sufficient to remove induced hydrogen.

Rodney C. Todd, CEF
- Ontario, Canada


(1999)

A. What kind of steel and what is the hardness? Usually embrittlement is not considered a problem below Rockwell C-40 or 180 ksi, although some callouts go as low as C-30. How hot and how long is the bake cycle for your E-coat? Have you run any test specimens? We have found tempered Belleville washers to be simple test pieces. Easily compressed and you can run a large number for statistical reliability,

C.A.Smith
aerospace - Nashville, Tennessee

----
Ed. note: Thanks, C.A.! That Belleville washer idea sounds like a great suggestion.



Is it possible to salvage parts that were not immediately baked?

(1999)

Q. Once parts have been determined to have hydrogen embrittlement failure, is there a way to "save" the parts? I have heard several different theories from; the embrittlement can still be baked out, to re-strip and re-plate the parts, to the parts are junk. Is there a definitive answer out there?

Kevin Almquist
- Danielson, Connecticut


(2000)

A. Once the material is found to have a H/E problem, the micro-structure has already sustained damage due to the "migration" of the trapped hydrogen (very small cracks). Re-working the parts will not correct the damage. This is only my opinion, but one based upon "ACTUAL" experiences related to H/E failures. My definitive answer would be "SCRAP" the affected product, try to define and correct the "ROOT CAUSE" and try again. This has been my experience.

David L. Dow
fastening systems - Automotive - Detroit, Michigan



thrashing

What is the mechanism of hydrogen embrittlement?

(2000) -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am looking for any reference information about hydrogen embrittlement (mechanism).

nina deleted
- Halifax, Canada


(2000)

A. There are many good books on this subject that you can research for your project, Nina. If hydrogen embrittlement related to metal finishing is your issue, Jack Dini's "Electrodeposition - The Materials Science of Coating and Substrates" has a very interesting chapter on the mechanism.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2000)

A. The basic situation is one little hydrogen atom lost inside the metal matrix (crystal), it takes up almost no room, can move easily through the crystal and causes very little stress to the crystal structure.

Then it meets another hydrogen atom, they're dead happy to meet each other and join to become one molecule of hydrogen gas. Gas takes up about 1000 times the volume, so the molecule puts a lot of localised stress on the crystal, a few more molecules in a few more places and then the trouble starts.

Ian Brooke
university - Glasgow, Scotland



(2000) -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I am doing a failure analysis on galvanized quench and tempered steel (.22C/1.32 Mn). I have read where the acid bath can cause hydrogen embrittlement in high-strength steels. Is it common to see failure due to hydrogen embrittlement in quench and tempered steels (Yield strength = 116 ksi)?

David Reinhart
- Longview, Texas



(2000)

Q. Hello-

What's a good test to establish whether or not the failure is due to Hydrogen Embrittlement (for fittings)?

Is a sustained load test for 72 hrs with 85% max. allowable load a good criterion?

Fittings are made from 8740 steel, Heat treat to 170-190 ksi and CAD plated per QQ-P-416 [link is to spec at TechStreet] and subsequently baked for 23 hrs.

KA

A Kamal
- New York, New York



(2000)

Q. Hello,

I am a student studying corrosion engr., I am presently studying hydrogen embrittlement, I like to know about the possible testing method of hydrogen embrittlement. If anybody can help me, I will really appreciate it. Thanks

B. Kannan
- India.



(2000)appended

Q. I am interested in plating of metal parts and the hydrogen embrittlement that may occur and also the relief of stress in such parts by baking.

Specifically, I ask if the stress relief occurs without baking and by the mere passage of time and, if so, what time is normal or does the part remain capable of failure until baked?

If the metal parts plated are not stress relieved after plating, does the metal and/or the plating process present some danger of brittleness and/or failure?

Jim McBroom
- Nashville, Tennessee


(2000)

A. Hydrogen embrittlement under plating does not relieve itself ever, because the problem is not the presence of hydrogen (which I suppose might dissipate over time), it's the damage that the hydrogen did to the metal. Baking must be done very shortly after the embrittling process, preferably immediately.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2001)

Q. I have conflicting reports from 2 test houses on analysis of screws with sheared heads. One opinion is hydrogen embrittlement and the other is high core hardness. Is there a definite diagnosis tool for hydrogen embrittlement.

James Wardle
- Newcastle, UK



(2002)

Q. Is there hydrogen after chromating or before that? When is produced hydrogen in a steel? Is the appearance of hydrogen depending on the chrome on the steel or depend on the proper steel (tensile strength?)

Albertodeleted
- Rosario, Santa Fe, Argentina


(2003)

A. Do you mean chromium plating?

Hydrogen enters steel during casting, cleaning by most common acids (except nitric), cathodic electrocleaning, electroplating, heat treating in reducing atmospheres and some welding processes. It can be a serious problem in highly stressed, high strength steels. There are several embrittlement mechanisms, but basically, the hydrogen adds to internal stresses and accumulates at defects, leading to failure at even low loads. The hydrogen embrittlement danger increases with increasing hardness and decreasing part thickness for a given type and amount of plating.

Hydrogen build-up is especially high in hard chromium plating from Cr+6 solutions due to the low cathode efficiency (large amperage required). The amount of hydrogen liberated at the cathode (workpiece) surface is proportional to the plating thickness. Steel of ultimate tensile strength 150 ksi or greater having residual stresses from machining, grinding, hardening, etc., should be stress relieved or shot peened prior to plating. Steel having a tensile strength of at least 160 ksi or HRC 36 shall be given a hydrogen bake-out at 191 °C (375 °F) or higher for 3 or more hours as soon as possible after plating. See QQ-C-320B or AMSQQC320 [link is to spec at TechStreet] CHROMIUM PLATING (ELECTRODEPOSITED), for more details.

Ken Vlach
- Goleta, California  

Ken received a special
"Contributor of the Year" award
from finishing.com for his numerous
helpful and well researched responses



De-embrittlement process

(2007)

Q. Please give advice on standard hydrogen de-embrittlement process. Please also advice on the material which have bypassed hydrogen de-embrittlement process. How can we correct it?

PRABHUNATH SINGH
HEAD FINISHING - ROHTAK, HARYANA, INDIA


First of two simultaneous responses -- (2007)

A. Prabhunath,

There is nothing that can be done to rescue parts that have missed de-embrittlement. The damage to the parts is time dependent and cannot be repaired, once the damage is done it is permanent. It is made even worse that you probably won't even be able to tell whether the parts have suffered embrittlement damage so unfortunately you should scrap them.

De-embrittlement requirements across the world differ slightly but are usually based either on material strength or material hardness (my particular company tends to work on strength).

As a rough guide (and I can only emphasise that it is a guide) materials below approximately 1100 MPa (160 ksi) do not need de-embrittlement. Materials between 1100 MPa and 1450 MPa (160-210 ksi) will need de-embrittlement at approximately 190-205 °C (375-400 °F) for about 6 hours. Steels greater than 1450 MPa and less than 1800 MPa (210-260 ksi) will need de-embrittlement for about 18 hours at 190-205 °C, for greater than 1800 MPa then 24 hours is normally recommended.

Just to make things more complicated materials with a low tempering temperature will be affected by de-embrittlement at high temperatures so should be de-embrittled at 130-140 °C (265-285 °F) for 6 hours minimum. This also applies to carburised and induction hardened parts. I'm sure there are other exceptions as well but they don't readily spring to mind at the moment.

I cannot think of a specification that is universally accepted as the de-embrittlement standard as every OEM I have either worked for or have worked on their parts have always had slightly different de-embrittlement requirements. If you are supplying to an OEM then you should use their specification; if you are the OEM then you should have a specification for de-embrittlement specific to the materials that you commonly use.

Saying all that, I'm sure that I will be corrected and one of the many experts who contribute regularly to this site will come up with the relevant specification you require!

Brian Terry
Aerospace - Yeovil, Somerset, UK


Second of two simultaneous responses -- (2007)

A. Hydrogen de-embrittlement process is to let escape Nascent Hydrogen from the surface of substrate which gets preferentially co-deposited with the basic deposit sought.
For removing such nascent hydrogen, one has to subject the plated components to the temperature of 210 +/-10 °C for 2 to 6 hours within 4 hours of plating.

In case some components have bypassed such operation, it is a matter of whether Nascent Hydrogen prevails in such component. However, one raw method to know the presence of Hydrogen is to subject such item in Paraffin Wax preheated to 100 °C. If traces of bubbles are found in the vicinity of immersed component, the Hydrogen De-embrittlement process would have been by-passed.

Arvinda Kumar
Process Manager - Ghaziabad, UP, India


(2007)appended

Q. I work in the fastener industry and this subject of hydrogen embrittlement comes up often with parts that are plated.

Over a period of time won't the hydrogen bleed out, or has the damage been done and the parts are scrap?

Richard Jarret
fasteners - Itasca, Illinois


(2007)

A. Hi, Richard. We appended your inquiry to a thread which answered it.

It's not the hydrogen that is the problem, it's the damage that the hydrogen has already done to the steel. Good luck.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



February 25, 2010

Q. Does zinc electroplating also affect the strength of the nuts? Surely a bolt would fail somewhere outside the nut and thread. This question purely because Electro Galvanized Zinc Blue nuts do look so much better than mechanical plating.

Chris Vermaak
racing - Heidelberg, Gauteng, South Africa


February 25, 2010

A. Hi, Chris. Although failure of a nut sounds less likely than failure of a screw, I do not accept the implication that failure won't happen in the nut. Picture the screw being made of high strength steel and the nut being made of glass :-)

Electroplating has no effect on soft mild steel, but does cause hydrogen embrittlement of high strength steel. Baking immediately after plating may solve the problem, but it may not -- a statistically valid testing regimen is necessary in order to know.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



June 15, 2011

Q. Hi,

Any Standard or OEM Approved for the Paraffin test to conclude the Hydrogen de embrittlement test?

Kannan Boopathi
- Salem, Tamilnadu, India



November 6, 2013

Q. We clean parts in solvent with a pH value 10 to 11; it is definitely not acidic. But Army says it will cause high strength steel hydrogen embrittlement. I just do not understand. You?

David Ho
- Milford, Connecticut, USA
  ^- Privately contact this inquirer -^


November 11, 2013

A. Previous entries in this thread have alluded to the phenomenon which I will describe forthwith: In electroplating, the article being plated is cathodic; and at this cathode, metal is deposited. But there is also cathodic inefficiency in which hydrogen gas is generated; the electroplating seals the hydrogen into the article being plated. So even if the parts never see a pH below 7, there can still be hydrogen embrittlement.

P.S.: After reviewing this thread, I should add this postscript: A few inquiries asked how one can be sure that failure is due to hydrogen embrittlement. One telling characteristic of hydrogen embrittlement is intergranular failure (metallurgists call it "rock candy"), which is clearly evident under strong magnification (roughly 500x or 600x). More rounded asperities in the fracture face would contraindicate hydrogen embrittlement. I have seen respected testing laboratories conclude that plating + breaking = hydrogen embrittlement. That is sometimes the case, but sometimes not. You have to look at the fracture face.

tom_rochester Tom Rochester
Plating Systems & Technologies, Inc.  

Jackson, Michigan, USA



November 12, 2013

thumbsup2Very interesting postscript, Tom, which I had never heard before.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


November 18, 2013

A. There is a phenomenon known as caustic embrittlement and is commonly associated with things that use very concentrated forms of caustic solution, or the solution is used under forcing conditions. I haven't seen anything that says pH 10-11 would be a problem unless you are using the solution as a cathodic cleaner, in which case you can generate hydrogen for embrittlement.

Brian Terry
aerospace - Yeovil, Somerset, United Kingdom


November 20, 2013

Q. My initial question may be not clear; sorry about that. We are CLEANING parts, not plating parts. We just simply clean parts in ultrasound tank with Omegaclean solvent (by Omegasonics). Thanks.

David Ho
- Milford, Connecticut, USA


November 20, 2013

A. For hydrogen embrittlement to occur, generally two factors must be present: (1) a mechanism for producing hydrogen, and (2) a process that seals the hydrogen into the substrate. Since neither of these two factors would appear to be present in your process, one can reasonable assume that it is hydrogen-embrittlement-free.

tom_rochester Tom Rochester
Plating Systems & Technologies, Inc.  
Jackson, Michigan, USA


November 21, 2013

Q. Out of curiousity, is the 'process that seals' required? I always thought that just exposure such as cathodic cleaning or acid etching was sufficient to pose a risk.

Willie Alexander
- Colorado Springs, Colorado


November 26, 2013

A. Hydrogen generated during cleaning or pickling (or etching) is usually considered "self-relieving" in that the hydrogen can escape easily. That is why phosphating and mechanical plating (to name two non-embrittling processes) are considered non-embrittling processes. Parts tested immediately after plating may exhibit transient hydrogen embrittlement, but this goes away as the hydrogen escapes at room temperature without baking.

tom_rochester Tom Rochester
Plating Systems & Technologies, Inc.  
Jackson, Michigan, USA

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