Hydrogen Embrittlement Zinc electroplating of hardened steel, acid pickling, heat treatment, ...

Research Report on the Impeding Influence of SurTec 101 on the Successive Nitride Process
SurTec Technical Letter 13b

In cooperation with the IWT Bremen (Stiftung Institut für Werkstofftechnik) was investigated, wether the application of SurTec 101 has a negative effect on the following nitration process (formation of barrier layers).

Cleaning as a Part of the Heat Treatment
SurTec Technical Letter 13a

The cleaning often seems a rather unimportant process, compared to following treatments like plating, heat treatment, etc.. Usually the cleaning is not considered as a worth increasing process (except if it is done at the end of a process sequence), the process consumes time and money and is regarded as inevitable. Actually, the cleaning is important for the quality and it influences the following processes dramatically. Hence, it is important to discuss the cleaning process being a fundamental step to reach best quality, indeed.

Dephosphating of Parts before Heat Treatment
SurTec Technical Letter 10

Before reshaping steel wire, e.g. forming the thread of screws, it has to be phosphated. The phosphate layer allows a better sliding and gives a temporary corrosion protection. These phosphate layers have to be removed completely before tempering. Otherwise glass like and diffusion inhibiting iron phosphorases would be formed during the heat treatment. These phosphorases are very brittle and would result in blisters and faults whilst successive zinc plating. By specific bath maintenance and good monitoring of the sequence of treatment steps, dephosphating baths can be increased both, life time and efficiency. This Technical Letter advices procedures proven in praxis for an increasing service life.

Hydrogen Embrittlement
SurTec Technical Letter 8

In several process steps of electroplating zinc, hydrogen is formed at the surface of iron parts. That is during pickling, cathodic electrolytical cleaning and zinc plating itself. The hydrogen can diffuse into the bulk material and, especially hardened parts can be affected badly by hydrogen brittlement causing stress and evenbraking off the material. How should a suited pre-treatment look like, particulary the pickling, to minimize the adsorption of hydrogen? Are there differences between the zinc processes and which effects do they have; are all types of electrolytes suitable? Which method is the best to remove adsorbed hydrogen out of the bulk without distructing the zinc layer? This Technical Letter answers these questions and shows concepts and methods to avoid hydrogen embrittlement.