PS.

50023<S>
Process Standard
HYDROGEN EMBRITTLEMENT RELIEF
Page: 1/10

Date: 30-NOV-2017

GLOBALLY HARMONIZED DOCUMENT

Change level Date Description of change

- 22-JAN-2015 Initial release. Harmonized version of the former Chrysler Group PS-9500<S>
4.1 Table 2 Update duration for embrittlement relief of plated parts
4.2.1 Emphasize temperature continuity for embrittlement relief.
A 30-NOV-2017
4.3.1 Prevent reuse of parts utilized for embrittlement testing
Updated active specification references

For Information, please contact the following references:

NAFTA Contact: Tress Kim

Phone number/e-mail address: +1 (248) 512-2442 / kim.tress@fcagroup.com
Department: Technical Specialist Functional Coatings

EMEA. Contact: Marchiaro Giancarlo

Phone number/e-mail address: +393667830938 / giancarlo.marchiaro@crf.it
Department: Product Development - EMEA

LATAM. Contact: Otavio Ferreira Campos Rodrigo

Phone number/e-mail address: +553121233734 / rodrigo.campos@fcagroup.com
Department: Product Development

APAC Contact China: Yang Jinkui Henry

Phone number: 1 801-866-8075 / jinkui.yang@fcagroup.com.cn
Department: Product Development Staff – 1400

ANY PRINTED COPY IS TO BE DEEMED AS UNCHECKED; THEREFORE THE UPDATED COPY MUST BE CHECKED IN THE APPROPRIATE WEB SITE

CONFIDENTIAL
THIS DOCUMENT MUST NOT BE REPRODUCED OR CIRCULATED TO THIRD PARTIES WITHOUT PRIOR WRITTEN CONSENT BY THE RELEVANT FCA COMPANY.
IN CASE OF DISPUTE, THE ONLY VALID REFERENCE IS THE ENGLISH EDITION
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HYDROGEN EMBRITTLEMENT RELIEF

TABLE OF CONTENTS

1 GENERAL ................................................................................................................................................. 3
1.1 Purpose .................................................................................................................................................. 3
1.2 Coverage of this Standard (Applicability) and Limitations on Usage ..................................................... 3
2 REFERENCES .......................................................................................................................................... 3
3 DEFINITIONS / ABBREVIATIONS / ACRONYMS / SYMBOLS ............................................................... 4
4 PROCESS AND PROCESS CONTROL REQUIREMENTS .................................................................... 4
4.1 Condition of the Part Prior to Processing ............................................................................................... 4
4.2 Procedure ............................................................................................................................................... 6
4.2.1 Baking Parts to Prevent Embrittlement ............................................................................................... 6
4.3 Process Control ...................................................................................................................................... 7
4.3.1 Hydrogen Embrittlement Test ............................................................................................................. 7
4.3.1.1 Test Load Determination .................................................................................................................. 7
4.3.1.1.1 Threaded Parts ............................................................................................................................. 7
4.3.1.1.2 Non-Threaded Parts ..................................................................................................................... 7
4.3.1.2 Sample Size Determination ............................................................................................................. 8
4.3.1.3 Performing Hydrogen Embrittlement Test <S> ................................................................................ 8
4.3.1.4 Test Methods ................................................................................................................................... 8
4.3.1.5 Suggested Fixturing Methods .......................................................................................................... 9
4.4 Inspection Requirements ....................................................................................................................... 9
4.4.1 Pass/Fail Determination ...................................................................................................................... 9
4.5 Re-process ............................................................................................................................................. 9
5 SPECIAL REQUIREMENTS ..................................................................................................................... 9
6 QUALITY ................................................................................................................................................. 10
7 TEST EQUIPMENT ................................................................................................................................. 10
7.1 Test Facilities ....................................................................................................................................... 10
7.2 Test Equipment .................................................................................................................................... 10
8 SAFETY PRECAUTIONS ....................................................................................................................... 10
9 APPROVED SOURCE LIST ................................................................................................................... 10
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1 GENERAL
This standard presents the process for avoiding hydrogen embrittlement in high-strength and spring steel
after various coating and plating finishes.

1.1 Purpose

This standard outlines the procedures and requirements for preventing hydrogen embrittlement in high
strength steel parts. High strength steel fasteners are covered by this standard but hexagonal nuts are
excluded. Hydrogen embrittlement can be caused by acid cleaning, phosphating or electroplating,
because of hydrogen absorption, and lack of relief before tensile stresses are applied to the material.
This standard is commensurate with SAE/USCAR-5 with the exception of the hardness value cut offs
where a specific procedure such as a holding period or a heat treatment is required. Where these
standards differ, the specific requirements in this standard take precedence over SAE/USCAR-5.

1.2 Coverage of this Standard (Applicability) and Limitations on Usage

For parts other than fasteners, hydrogen relief is required for coated parts with a hardness of Rockwell C
32 or greater, or tensile strengths of 1040 N/mm 2 or greater, including surface hardened parts meeting
these conditions.

For fasteners, the hardness levels referred to in this standard that will determine the type of hydrogen
relief required is the “specified case hardness” for case-hardened fasteners (MS.50077<S>,
MS.90079<S>, MS.90080<S>, and MS-5001<S>). For through-hardened and tip-hardened fasteners
(MS.50076<S>, MS.50077<S>, MS.90079, MS-3517<S>, MS-5766<S>, and MS-8253<S>), the hardness
that shall apply in determining the type of hydrogen relief is the “specified core hardness.”

2 REFERENCES

Table 1 - References
Document
Document Title
Number
FCA Standards
CS-9003 REGULATED SUBSTANCES AND RECYCLABILITY
CS-9800 APPLICATION OF THIS STANDARD, THE SUBSCRIPTION SERVICE, AND APPROVED
SOURCES
MS-3517<S> INCH SERIES EXTERNALLY THREADED STEEL FASTENERS
MS.90080<S> SELF-TAPPING SCREWS AND RIVETS
MS.90079<S> SELF DRILLING AND TAPPING SCREWS
MS-5479<S> HIGH STRENGTH STEEL SERRATED BOLTS
MS-5766<S> INCH SERIES HIGH STRENGTH SCREW AND CONED WASHER ASSEMBLIES
MS.50076<S> INTERNALLY THREADED FASTENERS FOR NORMAL USE
MS.50077<S> EXTERNALLY THREADED FASTENERS FOR NORMAL USE
MS-8253<S> INDUCTION TIP HARDENED - THREAD ROLLING - TAPPING SCREWS
PF-SAFETY<S> PRODUCT SAFETY – USE OF SAFETY SHIELDS <S>
PS-7000 OUTSIDE DESIGNED AND DEVELOPED ITEMS - FCA US LLC AND SUPPLIER
RESPONSIBILITIES
PS.50042 ZINC MECHANICALLY DEPOSITED COATINGS
PS.50036 ZINC ELECTROPLATED COATINGS
PS.50040 TIN ELECTROLYTIC PLATING OF FERROUS OR COPPER SUBSTRATES
PS.50034 ZINC PHOSPHATING FOR FERROUS MATERIAL - PARTS AND FASTENERS
PS.50035 MANGANESE PHOSPHATING FOR FERROUS MATERIAL – PARTS AND FASTENERS
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Table 1 - References
Document
Document Title
Number
PS.50031 ZINC NICKEL ALLOY ELECTRODEPOSITED COATINGS
PS-8956 CONDUCTIVE PLATED COATINGS FOR ELECTRICAL CONNECTORS AND CORROSION
PROTECTION
9.01102 QUALITY OF SUPPLIES - FIAT CHRYSLER AUTOMOBILES EMEA REGION
9.01103 PRODUCT QUALITY AND CONFORMITY CERTIFICATE (C.Q.C.)
SAE Standards
SAE/USCAR-5 AVOIDANCE OF HYDROGEN EMBRITTLEMENT OF STEEL
Other Standards
ISO/TS-16949 QUALITY MANAGEMENT SYSTEMS - PARTICULAR REQUIREMENTS FOR THE APPLICATION
OF ISO 9001:2008 FOR AUTOMOTIVE PRODUCTION AND RELEVANT SERVICE PART
ORGANIZATIONS

3 DEFINITIONS / ABBREVIATIONS / ACRONYMS / SYMBOLS

°C DEGREES CELSIUS (TEMPERATURE)
I.D. INNER DIAMETER
in INCH
mm MILLIMETERS
O.D. OUTER DIAMETER

4 PROCESS AND PROCESS CONTROL REQUIREMENTS

4.1 Condition of the Part Prior to Processing

Categories of Surface Treatment

A. Acid Cleaning

Acid cleaning must be minimized on high-strength/high-hardness steel parts because it can contribute to
hydrogen embrittlement. Therefore, if fasteners or parts with specified tensile strengths of 1040 N/mm 2 or
greater, or Rockwell hardness of HRC 32 or greater, are to be acid pickled, it is required that a procedure
be established for processing the parts that limits the time in the acid to a maximum of 10 minutes.
Controls shall be implemented and records kept on the type and concentration of the acid used, exposure
time, acid bath temperature, and the type and amount of inhibitor. It is required that records be kept on
when the parts entered and exited the various processing stations. For automatic plating equipment, a
record of the cycle time will suffice until the cycle is changed or until the line is interrupted due to
breakdown or otherwise.

When hydrogen is absorbed by acid cleaning, it will usually dissipate within 48 hours. It is the
responsibility of the primary supplier to make sure the parts are not delivered to the plant before this time
period has elapsed (see Table 2).

As an option, the parts can be placed in a preheated, forced-air-circulating oven for one (1) hour at 115°C
+/- 10 °C. See Section 4.2.1 for details on the baking procedure.

B. Phosphating (e.g., PS.50034, PS.50035)

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All parts with a specified tensile strengths of 1040 N/mm2 or greater, or Rockwell hardness of HRC 32 or
greater, which are acid cleaned (not to exceed 10 minutes) and phosphated shall be held in the supplier’s
plant for 48 hours or baked for one (1) hour at 115°C +/- 10°C. (See Table 2 and Section 4.2.1 for Baking
Procedure).

C. Mechanical Plating (e.g. PS.50042)

Some hydrogen is absorbed during the acid cleaning and processing procedure of the mechanical plating
process. When steel parts with a specified tensile strengths of 1040 N/mm 2 or greater, or Rockwell
hardness of HRC 32 or greater are coated by this procedure, they should be held for 48 hours before
shipping to the plant. As an option, the parts may be baked for 1 hour at 200°C +/- 10°C. (See Table 2
and Section 4.2.1 for Baking Procedure).

The approved sealer shall be applied after baking.

D. Electroplating: Examples: Zinc Plating (PS.50036), Zinc Alloy Plating (PS.50031), Tin Plating of
Spring Steel (PS.50040), and Tin-Zinc Alloy Plating (PS-8956E)

High-strength/high hardness steel parts with a tensile strengths of 1040 N/mm 2 or greater, or Rockwell
hardness of HRC 32 or greater, that are to be electroplated, must be plated to the requirements of
relevant plating standard and MUST BE PROPERLY BAKED WITHIN ONE HOUR after plating. Refer to
Table 2 for bake schedule and Section 4.2.1 for baking procedure.

Table 2 - Hydrogen Relief Requirements

Tensile
Process Examples Strength / Hydrogen Relief
Hardness HRC
Acid Pickle (1) Clean only 1040 N/mm2 or Hold parts for 48 hours.
Rust and scale greater
removal Option: Bake parts for 1 hour at 115 +/- 10 degrees C.
HRc 32 or greater
(No finish other than
oil is applied.)
Phosphate (1) Zinc 1040 N/mm2 or Hold parts for 48 hours.
Phosphate, greater
Magnesium Option: Bake parts for 1 hour at 115 +/- 10 degrees C.
Phosphate HRc 32 or greater
Mechanical Plate (1) Mechanically 1040 N/mm2 or Hold parts for 48 hours.
deposited greater
zinc and zinc Option: Bake parts for 1 hour at 200 +/- 15 degrees C.
alloys HRc 32 or greater
Electroplated (2) Zinc and 1040-1220 N/mm2 200 +/- 10 degrees C for 4 hours minimum bake
Zinc alloys
HRc 32 to 36
1220-1500 N/mm2 Bake parts for 200 +/- 10 degrees C for 12 hours minimum (*)

HRc 37 to 49
Electroplated (2) Tin Zinc alloy 1040-1220 N/mm2 Bake parts for 185 +/- 5 degrees C for 4 hours minimum

HRc 32 to 36
1220 - 1500 N/mm2 Bake parts for 185 +/- 5 degrees C for 12 hours minimum (*)

HRc 37 to 49
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Table 2 - Hydrogen Relief Requirements

Tensile
Process Examples Strength / Hydrogen Relief
Hardness HRC
NOTE 1: The hydrogen embrittlement test is not required for these finishes, or for parts with Rockwell hardness less than HRC
32 or tensile strength less than 1040 N/mm 2.
NOTE 2: Unless otherwise specified, and excluding tip-hardened fasteners, high-strength steels having a tensile strength
greater than 1500 N/mm2 or Rockwell hardness greater than HRC 49 should not be electroplated. High-strength
steels having a tensile strength greater than 1040 N/mm 2 or Rockwell hardness greater than HRC 32 should not be
specified to a deposit thickness more than Code 30 (8 micrometers). On all existing drawings where Code 50 (13
micrometers) is specified for a part with tensile strength of 1220 N/mm 2 or greater, or Rockwell hardness of HRC 32
or greater, are hereby understood to be Code 30 (8 micrometers). Testing for hydrogen embrittlement per section
4.3.1 is required.
(*) Applicators may have reduced requirements provided the following criteria are met:
 Each location is included on the Engineering Approved Source List for the appropriate plating standard.
 Statistical control of the process and analysis has been demonstrated.
 Computer-tracking system is utilized that includes time and date controls for each process.
 On-going compliance to Section 4.3 Hydrogen Embrittlement Test verification is demonstrated.
If approved, FCA Materials Engineering/FCA GML may provide written authorization to reduce the requirements to an 8-hour
hydrogen embrittlement relief duration.

4.2 Procedure

4.2.1 Baking Parts to Prevent Embrittlement

High-strength/high-hardness steel parts MUST BE PROPERLY BAKED in a well-controlled, calibrated,

hot-air-recirculating batch oven, or in a continuous conveyor type oven, within one hour after processing.
The core of the load must reach embrittlement relief temperature within two (2) hours after receiving the
plating layer. A baking schedule based on hardness is described in Table 2.

The time for the parts to come up to temperature SHALL NOT be counted as part of the minimum bake
time. Because the oven air temperature can differ from the temperature of the parts in a batch oven, the
temperature of batch baked parts must be monitored with a thermocouple placed in the middle of the load
of parts, in the last place in the oven to reach the bake temperature in order to insure that the proper
baking time and temperature are reached. For continuous bake ovens, a temperature trace through the
oven must be run with a calibrated thermocouple in the lowest temperature position, at least once a year.

Methods should be implemented to aid the heat-up rate of the parts. This includes reducing the size of
the load placed in the oven, using smaller containers, and using containers fabricated from wire mesh
and perforated sheet to allow air circulation into the load. The type of fastener or part, the configuration of
the load in the oven, oven identification, and load weight, etc., must be recorded and kept on file for future
reference. It is required that records be kept on the bake temperature and when the parts entered and
exited the bake oven.

Temperature shall be maintained continuously for the entire duration. If part temperature falls below the
defined range for any length of time during the relief cycle, the parts shall be quarantined and the
customer and end user shall be notified in writing for disposition. If the temperature exceeds the range,
the parts shall be quarantined and the customer notified for disposition.

The parts shall be baked prior to the application of oil or sealer.

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4.3 Process Control

4.3.1 Hydrogen Embrittlement Test

NOTE: This is a destructive test. Parts used for this test may not be used for further testing or
inspections unless otherwise specified case by case. Tested parts shall not be mixed with production
parts.

Hydrogen embrittlement testing must be applied to finished parts prior to shipment. A torque/tension test
is used for threaded parts and a tensile test is used for non-threaded parts. The test consists of three
steps:

A. Determine the ultimate torque or tensile stress to failure for threaded and non-threaded parts
respectively.

B. Load the parts to 80% of the ultimate torque or tensile stress.

C. Maintain the torque or tensile stress for 48 hours. Whenever possible, the test fixture should simulate
the intended application.

It is the sole responsibility of the supplier to ensure that the test procedure, fixture and loads are sufficient
to detect the presence of hydrogen embrittlement in the finished part prior to shipment.

4.3.1.1 Test Load Determination

4.3.1.1.1 Threaded Parts

Randomly select a minimum of five parts from the lot being evaluated to establish the test load for the
stress test. Note that the five-part sample is only to establish the test load used for the hydrogen
embrittlement tests. The hydrogen embrittlement test sample size is determined in Section 4.3.1.2.

A. Apply torque to the test part or the mating part of the text fixture until ultimate failure of the test
assembly occurs. The assembly must use material of comparable strength levels. Parts of the same
configuration must be used throughout the hydrogen embrittlement test. Record the failure torque for
each of the five test fasteners. Suggested fixturing methods are discussed in Section 4.3.1.5. The
test fixture must represent the intended use of the fastener, and does not have to be application
specific. Hand or power tool tightening is acceptable; however, the selected tightening method must
also be used in performing the hydrogen embrittlement test (Section 4.3.1.3).

B. The torque to be used in the hydrogen embrittlement test shall be 80% of the average of the five
failure torque readings taken in Step 1. This torque value does not necessarily correspond to the
actual application installation torque for the part.

C. For threaded parts proceed to Section 4.3.1.2 Sample Size Determination and Section 4.3.1.3
Performing Hydrogen Embrittlement Test.

4.3.1.1.2 Non-Threaded Parts

Randomly select a minimum of five parts from the lot being evaluated. Note that the five-part sample is
only to establish the test load used for hydrogen embrittlement tests. The hydrogen embrittlement test
sample size is determined in Section 4.3.1.2.
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A. Determine an acceptable tensile test method for the geometry and configuration of the part. The test
fixture and test procedure must be agreed upon by FCA US Supplier Development and
Materials/Fastener Engineering. Suggested fixturing methods are discussed in Section 4.3.1.5.
Apply a tensile load to the part until failure of the test assembly occurs and record the maximum
tensile load for each of the five test fasteners. Parts of the same configuration must be used
throughout the hydrogen embrittlement test.

B. The load to be used in the hydrogen embrittlement test shall be 80% of the average of the five
maximum tensile load readings taken in Step A.

C. For non-threaded parts proceed to Section 4.3.1.2 Sample Size Determination and Section 4.3.1.3
Performing Hydrogen Embrittlement Test.

4.3.1.2 Sample Size Determination

A lot for the purpose of the hydrogen embrittlement test is defined as follows. For a batch oven, a lot is a
load of baked parts with the same part number. For a continuous baking furnace, a lot (for a particular
part number) is to be defined by the supplier as is agreeable with their process; keeping in mind that if a
failure should occur during the subsequent hydrogen embrittlement test, the lot shall be scrapped. The
lot shall be defined such that all processing traceability is maintained for each part number/lot
identification. Samples used for the hydrogen embrittlement test must be randomly selected from the lot.

The number of parts to be subjected to the hydrogen embrittlement test must be 115 pieces if the lot is
2,300 parts or greater, or 5% of the quantity of the lot if less than 2,300 parts. Parts that are comprised of
several components must be tested as whole assemblies.

4.3.1.3 Performing Hydrogen Embrittlement Test <S>

A. The total numbers of parts determined in Section 4.3.1.2 are to be subjected to the hydrogen
embrittlement test.

B. These parts are to be loaded using the same fixture, the same loading methods and the same test
load determined in Section 4.3.1.1.1 for threaded parts or Section 4.3.1.1.2 for non-threaded parts.
Parts which fail while attempting to be assembled to the test torque (load) should be discarded and
cannot be counted as part of the test lot.

C. These parts are to be held at load in the fixture for a period of 48 hours. After the 48 hours have
elapsed:

- For threaded parts: Reapply test torque and then remove from the fixture and examine per
Section 4.4.1.
- For non-threaded parts: Remove from the fixture and examine per Section 4.4.1.

4.3.1.4 Test Methods

A. Flat and coned washers pre-assembled or loose, should be tested on a fixture having an oversize
clearance hole so that a high tensile stress is induced to the washer. Pre-assembled screw and
washer, and nut and washer assemblies are to be loaded against a test plate, or spacer. The
minimum and maximum hole diameter of the test plate or spacer must be within 80% of the
minimum and maximum outside diameter of the washer respectively. The thickness of the test plate,
or spacer must be greater than the minimum washer thickness being tested. Loose washers are to
be tested in the same manner. The minimum across flats dimension of the hex bolt or hex nut being
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used to test the loose washer must not be greater than 1.5 times the basic thread size. Five parts
must be loaded to 80% of the ultimate strength of the test assembly as determined in Section 4.3.1
1.1 for the hydrogen embrittlement test.

B. Screws, bolts, or nuts without washers must be loaded against a test plate with a minimum diameter
clearance hole equal to the nominal thread size plus 0.50 mm for fasteners M6 (1/4 inch) and
smaller, and plus 1.0mm for larger diameters.

4.3.1.5 Suggested Fixturing Methods

The following suggestions are provided to assist in establishing the test load and method of test to induce
high tensile stress for performing the hydrogen embrittlement test.

A. Screws may be seated against a 4-degree wedge to represent a worst case assembly condition. A
flat washer may be inserted between the screw and the wedge test plate to eliminate the effects of
torque robbing features. Serrations, rings, etc. may prevent torqueing the fastener to failure due to
socket cam off or recess bit cam out. (NOTE: The washer I.D. should not be larger than 0.04 in (1.0
mm) over the major diameter of the screw.). The O.D. of the washer should be equal to or greater
than the maximum flange diameter of the screw being tested.

B. Large diameter threaded fasteners may be lubricated to reduce the torque required to fail the fastener
and establish the test torque. If lube is used, the same lube must be used and applied for the entire
test.
C. Screws with internal drives which cannot be torqued to failure due to bit cam out or failure should be
tested to the maximum torque obtainable without bit cam out or failure. This will be the test torque for
the hydrogen embrittlement test for this type of fastener. The operator performing the test must use
due diligence to apply sufficient pressure with the tool to prevent premature cam out.

D. Tapping screws may be tested using pre-threaded holes in test plates to achieve screw failures
instead of thread strippage. Torsional strength testing of the fastener must still be performed where
required.

E. Screws may be tested by applying torque to head of the screw or to a nut if a nut is used as part of
the test set up.

4.4 Inspection Requirements

4.4.1 Pass/Fail Determination

Using 10X magnification or greater, visually inspect the parts which have undergone the 48 hour test.
The parts shall be free of cracks or multi-piece fractures. If cracking or fracturing has occurred on one or
more of the samples, the entire lot shall be rejected and scrapped (no rework of these parts is allowed). If
none of the sample parts have cracked or fractured, the lot may be shipped.

4.5 Re-process

Not allowed.

5 SPECIAL REQUIREMENTS
Refer to CS-9003 for components produced for vehicles designed in NAFTA markets, or 9.01107 for
components produced for vehicles designed in EMEA markets.
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6 QUALITY
For components that will be part of a vehicle designed in NAFTA and sold in all markets, conformance to
the material characteristics described by CS-9800 and PS-7000 shall be met.

For components that will be part of a vehicle designed in EMEA and sold in all markets, the material
characteristics defined by 9.01102 and 9.01103 shall be met.

7 TEST EQUIPMENT
All instruments must be certified and maintained in accordance with ISO TS 16949. The personnel shall
be properly trained and qualified.

7.1 Test Facilities

There must be a structure within the production site equipped with the means to perform the required
inspections described within this standard.

7.2 Test Equipment

Test fixtures shall be designed for specific part configuration as described in Section 4.

8 SAFETY PRECAUTIONS
Not applicable.

9 APPROVED SOURCE LIST

Not applicable.