NATIONAL BUREAU OF STANDARDS REPORT

9942

HYDROGEN EMBRITTLEMENT OF CHROMIUM

PLATED PRINTING PLATES

To

Electrolytic Section

Bureau of Engraving and Printing

Washington, D. C.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards1 was established by an act of Congress March 3, 1901. Today, in addition to serving as the Nation’s central measurement laboratory,

the Bureau is a principal focal point in the Federal Government for assuring maximum application of the physical and engineering sciences to the advancement of technology in industry and commerce. To this end the Bureau conducts research and

provides central national services in three broad program areas and provides central national services in a fourth. These are: (1). basic measurements and standards,

(2) materials measurements and standards, (3) technological measurements and

standards, and (4) transfer of technology.

The Bureau comprises the Institute for Basic Standards, the Institute for Materials

Research, the Institute for Applied Technology, and the Center for Radiation Research.

THE INSTITUTE FOR BASIC STANDARDS provides the central basis within the

United States of a complete and consistent system of physical measurement, coor- dinates that system with the measurement systems of other nations, and furnishes

essential services leading to accurate and uniform physical measurements throughout

the Nation’s scientific community, industry, and commerce. The Institute consists , of an Office of Standard Reference Data and a group of divisions organized by the

following areas of science and engineering

Applied Mathematics—Electricity—Metrology—Mechanics—Heat—Atomic Physics—Cryogenics2—Radio Physics2 —Radio Engineering2—Astrophysics2 —Time

and Frequency.2 THE INSTITUTE FOR MATERIALS RESEARCH conducts materials research leading to methods, standards of measurement, and data needed by industry, commerce,

educational institutions, and government. The Institute also provides advisory and

research services to other government agencies. The Institute consists of an Office of

Standard Reference Materials and a group of divisions organized by the following

areas of materials research:

Analytical Chemistry—Polymers—Metallurgy — Inorganic Materials — Physical

Chemistry.

THE INSTITUTE FOR APPLIED TECHNOLOGY provides for the creation of appropriate opportunities for the use and application of technology within the Federal Government and within the civilian sector of American industry. The primary functions

of the Institute may be broadly classified as programs relating to technological meas- urements and standards and techniques for the transfer of technology. The Institute

consists of a Clearinghouse for Scientific and Technical Information,3 a Center for

Computer Sciences and Technology, and a group of technical divisions and offices organized by the following fields of technology:

Building Research—Electronic Instrumentation — Technical Analysis — Product

Evaluation—Invention and Innovation— Weights and Measures — Engineering

Standards—Vehicle Systems Research.

THE CENTER FOR RADIATION RESEARCH engages in research, measurement,

and application of radiation to the solution of Bureau mission problems and the

problems of other agencies and institutions. The Center for Radiation Research consists of the following divisions

Reactor Radiation—Linac Radiation—Applied Radiation—Nuclear Radiation.

1 Headquarters and Laboratories at Gaithersburg', Maryland, unless otherwise noted ; mailing address Washington, D. C. 20234.

2 Located at Boulder, Colorado 80302. Located at 5285 Port Royal Road, Springfield, Virginia 22151.
NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

3120641

NBS REPORT

9942

HYDROGEN EMBRITTLEMENT OF CHROMIUM

PLATED PRINTING PLATES

By

I. J. Feinberg

Engineering Metallurgy Section

Metallurgy Division

To

Electrolytic Section

Bureau of Engraving and Printing

Washington, D. C.

IMPORTANT NOTICE NATIONAL BUREAU OF S

for use within the Government

and review. For this reason, t whole or in part, is not auth Bureau of Standards, Washing

the Report has been specitical

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

ess accounting documents intended

s subjected to additional evaluation

e listing of this Report, either in he Office of the Director, National by the Government agency for which

copies for its own use.

<^NBS>

U.S, DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

Hydrogen Embrittlement of Chromium

Plated Printing Plates

It has been suggested that hydrogen embrittlement may occur during

the chromium plating of printing plates and may contribute to their

premature failure. The results of an investigation inquiring into

whether printing plates can incur hydrogen embrittlement and into the

benefits to be obtained from a baking treatment intended to alleviate

this condition are presented in this report.'

Test Material and Procedure ; Two types of tests were employed in this

investigation. One type involved "delayed failure" tests on thin,

notched specimens, Figure 1. The other involved guided bend tests on specimens 0.180 inch thick, l .0 inch wide and 6.0 inch long. Specimens

for both types of tests were cut from the same virgin Moltrup plate.

The long axes of the specimens were aligned in the plate rolling

direction. Chromium plating was applied on as-received polished surfaces.

Case hardening, tempering, and chromium plating were conducted by the

Bureau of Engraving and Printing using their established procedures.

Designated specimens were baked at ^-00°F for four hours at NBS.

In the delayed failure tests plated notched tensile specimens were

loaded statically at 70 percent of the notch tensile strength of an unplated notched specimen. Guided bend tests involved bending of

specimens around a mandrel 0.75 inch thick.

Delayed Failure Test Results ; Delayed failure test results are given in

Table 1. Failure of unbaked plated specimens occurred after they were

loaded for one-half hour at a stress equal to JO percent of the notched

tensile strength of unplated specimens. Failure of baked specimens

similarly loaded was delayed for 200 hours.

Bend Test Resu 1 ts : All of the case-hardened and case-hardened and plated

bend test specimens fractured in the bend tests. A typical fracture

surface is shown in Figure 2. It is composed of a thin flat area which

coincides with the case on the outside of the bent portion and a more extensive fibrous area largely coinciding with the core. These fractographic features indicate that fracture was initiated in a brittle

manner in the case and then propagated in a q uas i -duct i I e manner through

the core.

This report covers only part of the investigation concerned with

the hydrogen embrittlement of printing plates. The effects of

hydrogen embrittlement and of a baking treatment on fatigue

properties will be discussed in a forthcoming report.

- 2 -

The bend test results, Table 2, reveal the loss in ductility that occurs at various stages of printing plate processing. They indicate

that case hardening lowers plate ductility and that chromium plating

has an additional adverse effect on this property.

Discussion and Conclusions : Hydrogen embrittlement often manifests itself

in the form of delayed, brittle failures which are characterized by failure

at relatively low applied loads. Accordingly, delayed failure tests were

employed in this investigation to detect possible hydrogen embrittlement.

The fact that specimens baked for hydrogen embrittlement relief withstood

a load equal to 70 percent of the notched tensile strength of the material

for 200 hours while unbaked specimens failed in only one-half hour would

seem to indicate that hydrogen embrittlement occurs during the chromium

plating of printing plates.

The case formed in case-hardening is incapable of appreciable plastic

deformation. It cracked early in the bend tests initiating fractures.

It is believed that the hard, brittle case is the chief factor in reducing

over-all plate ductility as measured by the bend tests.

The delayed failure test, which provides a more positive indication

of hydrogen embrittlement than a bend test of the type employed, revealed

that hydrogen embrittlement of printing plates occurs during chromium

plating. It is our opinion that baking of plates at 400°F for 4 hours

be applied to obtain relief from hydrogen embrittlement. Baking should

take place as soon after plating as possible.

USCOMM-NBS-DC

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Failure

Test

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Figure 2. Fracture surface of bend test specimen, D-2.

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