Because introduction of hydrogen during bright-cadmium electroplating of high strength steels causes hydrogen-stress cracking, a program was undertaken to evaluate various processes and materials. Report describes effectiveness of inhibitors for reducing hydrogen absorption by steels

Elsea, A. R.

Fletcher, E. E.

Groeneveld, T. P.

English

NASA Technical Reports Server

November 1969	 Brief 69-10606 
• NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
------•	 - _____E._. -	 F—	 - 
Literature Review on Pickling Inhibitors 
and Cadmium Electroplating Processes 
The problem of hydrogen-induced delayed brittle 
failure, or hydrogen-stress cracking, of parts fabricated 
from high-strength steels has been the subject of a 
large research effort during the past five years. The 
primary reasbn for this problem was that most of 
these high-strength steels must be protected from 
corrosion in their service environments. The preferred 
method of providing this protection was cadmium 
electroplating. However, the application of electro-
deposited coatings to solve corrosion problems, or to 
provide other desirable surface qualities, could make 
the part susceptible to failure by hydrogen-stress 
cracking because, frequently, hydrogen was introduced 
during the cleaning, pickling, and electroplating 
operations. 
As a result of hydrogen-stress-cracking failures 
attributed to hydrogen introduced during bright-
cadmium electroplating, restrictions were placed on 
the use of cadmium electroplating on certain steels 
having tensile strengths greater than 220,000 psi. 
Thus, it was necessary for manufacturers to resort 
to other methods of providing corrosion protection 
that were inferior to bright-cadmium electroplates 
in the protection provided. Consequently, many 
studies of electroplating processes, particularly 
cadmium electroplating, have been conducted to 
determine whether one or more processes could be 
used for electroplating ultrahigh-strength steels 
without the likelihood of encountering hydrogen-
stress-cracking failures. 
These studies showed that most ultrahigh-strength 
steels were embrittled to various degrees by virtually 
all of the common electroplating processes, includ- 
ing cadmium, chromium, zinc, tin, nickel, lead,
copper, and silver. These earlier studies also showed 
that the amount of hydrogen entering steel speci-
mens during certain electroplating processes might 
be as great as that introduced during severe cathodic 
charging and that more hydrogen sometimes was 
introduced during pickling or cathodic cleaning 
prior to electroplating than during the actual plat-
ing operation. As a result of these findings, some 
work was expended in evaluating the hydrogen-
embrittling tendencies of preplating cleaning and 
pickling processes, particularly on the effectiveness 
of inhibitors in minimizing hydrogen absorption 
during acid pickling. In addition, these studies 
showed that the sustained-load tensile test employ-
ing notched bars was the most sensitive method for 
evaluating the embrittling tendencies of cleaning and 
electroplating processes. 
Because of numerous confusing and conflicting 
statements contained in the technical literature con-
cerning the hydrogen-embrittling tendencies of various 
cleaning, pickling, and electroplating processes and 
concerning the susceptibilities to hydrogen-stress 
cracking of various high-strength alloys, a program 
was undertaken to evaluate various processes and 
materials. The first survey constituted a review of 
the literature on the phenomenon of hydrogen-stress 
cracking and the embrittling tendencies of conven-
tional cleaning, pickling, and electroplating processes. 
The results of numerous investigations into this prob-
lem area were included along with data on the effec-
tiveness of various hydrogen-embrittlement relief 
treatments. The report on the literature and industrial 
survey also presented information on reportedly low-
hydrogen-embrittling and nonhydrogen-embrittling 
(continued merle f) 
This document was prepared under the sponsorship of the National 	 Government assumes any liability resulting from the use of the 
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cleaning; pickling, and electroplating processes and 
on hydrogen-embrittlement relief treatments. 
This report describes the results of a literature and 
industrial survey of the available information on the 
effectiveness of inhibitors for reducing hydrogen 
absorption by steels during acid pickling and on addi-
tional low-hydrogen-embrittling and nonhydrogen-
embrittling cadmium-electroplating processes. No 
attempt was made to repeat the information on pickl-
ing inhibitors and cadmium-electroplating processes 
presented in the previous reports. 
Notes: 
1. Several organic compounds have been shown to 
be quite effective in reducing attack on a hydrogen 
absorption by low-carbon steels during acid pickl-
ing. Thesç compounds warrant further study to 
determine their effectiveness in reducing hydro-
gen embrittlement in certain ultrahigh-strength 
steels. 
2. This literature review should prove valuable to 
metallurgists, producers of steel, and to the air-
craft and related industries.
3. No further documentation is available. Inquiries 
may be directed to: 
Technology Utilization Officer 
Marshall Space Flight Center 
Huntsville, Alabama 35812 
Reference: TSP69-10606 
Patent status: 
No patent action is contemplated by NASA. 
Source: T. P. Groeneveld, E. E. Fletcher, 
and A. R. Elsea of 
Battelle Memorial Institute 
under contract to 
Marshall Space Flight Center 
(MFS- 14421)
. 
. 
Brief 69-10606	 Category 03


Literature review on pickling inhibitors and cadmium electroplating processes

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