We supply a customer with a latch that has a forged steel component, which is e-coated. A recent lot showed signs of being brittle. Can e-coat andphoretic paint processes create hydrogen embrittlement?
Craig Baker buyer - Windsor, Connecticut, USA
July 29, 2010
Hydrogen embrittlement is normally never seen in CED coating. De embrittlement is carried out by heating the electroplated part as hydrogen embrittlement is very common in electroplating. An E-coated part is always baked and even if hydrogen embrittlement is suspected, this baking process should be curing it. I hope the part without the coating was also tested for comparison?
Gurvin Singh Mohali, Punjab, India
August 6, 2010
Dear Craig Baker Brittleness will happen for lot of reasons. Even in E-coat also it is possible. In Electrical method possibilities are more. we are not able to do the de-embrittlement after e-coat. Better you check the parts as per Gurvin Singh with & without coating. If you have the problem Before coating, better you do the Stress relief process before coating. if, you have the problem in After coating also, do the stress relief process.
Kannan Boopathi - Salem, Tamil Nadu, India
Further to what Mr Gurvin has written, Id like to add that the current used in CED is too minimal to cause generation of Hydrogen and that the epoxy covers the component almost simultaneously ensuring no generation of Hydrogen.
Since you have mentioned its a forging, please look into the pretreatment process, Id suspect a pickling operation has crept in someplace. Do the comparative tensile test on a part as it is, after pretreatment; and after E-Coat to determine the cause of failure.
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