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Derek Lanz
phone: (203) 575-9450
fax: (203) 753-1564

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114 Porter Street
P.O. Box 2545
Waterbury, CT 06708
ISO 9001-2008 Registered

Hydrogen Embrittlement Relief

Hydrogen embrittlement is a metallurgical interaction which occurs between atomic hydrogen and the metallic atomic structure, primarily in high strength steels. The ability of the steel to deform-bend-stretch under load is inhibited which can cause brittleness and cracking. Hydrogen can be introduced in steel production, stamping, cleaning, and plating.

Certain types of steel are more susceptible to embrittlement. Steels that have been heat treated to a harness of Rockwell C31 or higher are often at greatest risk. Hydrogen can also be introduced during the fabrication and/or welding of a steel component. During pre-electroplating, the cleaning and certain pickling solutions may also introduce hydrogen into the steel.

The most popular accepted method to help alleviate hydrogen embrittlement is with a process called, “relief-baking.” Customers should use the following criteria to determine the need for hydrogen embrittlement relief (baking).

a) Any high strength steel having a Rockwell Hardness (HRc) of 31 or higher and/or a tensile strength of 1000 Mpa or higher, should be baked between 374°-428°F.

b) The baking duration should fall between 8 – 22 hours, depending on the actual hardness rating/tensile strength of the steel.

Baking your parts after plate is an efficient method for relief of hydrogen embrittlement. Our “bake out process” is consistently controlled and monitored by specific bake personnel who monitor your order in one of our multiple large calibrated bake ovens with automatic chart recorders. Fast transfer times from plate to bake, consistent temperature applied to every part using specially designed trucks, racks, and baskets, which allow airflow around all parts, and accurate bake time at temperature diffuses the maximum amount of hydrogen through the steel part. At Waterbury Plating we develop a specific control plan and traveler for each part indicating bake time, temperature, and any special instructions. This information is checked against the customer order and automatically is entered on the daily production schedule for processing. The operator must have all four documents (control plan, traveler, customer order, and production schedule) before processing the part. We invite you to call us and visit our plant for more detailed information.

Waterbury Plating Company obviously does not manufacture metal and we are not aware of your proprietary design considerations, operating stresses, metal composition or metal hardness level of any part sent to us. To help reduce the risk of hydrogen embrittlement, we strongly suggest that our customers abide by ASTM standard B850-98 (reapproved: 2009), for relief baking times. It is important you indicate to us at the time of the order, the correct hardness level of the steel part(s) as well as the correct bake time that is desired.

ASTM
Partial list of hydrogen embrittlement-relief treatment bake times/temperatures for some common high-strength steels 

Tensile Strength
(MPa)

Tensile Strength
(000 psi)

Rockwell
Hardness HRc

Post-Plate Bake time
@ 190° - 220° c.
or 374° - 428° F.

1701-1800
1601-1700
1501-1600
1401-1500
1301-1400
1201-1300
1101-1200
1001-1100
247-261
232-247
218-232
203-218
189-203
174-189
160-174
145-160
49-51
47-49
45-47
43-45
39-43
36-39
33-36
31-33
Minimum 22 hours
Minimum 20 hours
Minimum 18 hours
Minimum 16 Hours
Minimum 14 Hours
Minimum 12 hours
Minimum 10 hours
Minimum   8 hours

*** The above strength-to-hardness comparison values are approximate only.

PER ASTM B850-98 (REAPPROVED 2009):
The heat treatment does not guarantee complete freedom from the adverse effects of hydrogen degradation.”

Controls & Recorders
 
Bake Ovens
controls and recorders image   bake ovens picture
Precise controls and chart recorders insure the proper bake operation is performed on each customers' parts
 
Large walk-in bake ovens permit high volume operations

 



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