Call: Clean-Sky 2 of the Horizon Europe Framework Programme H2020

Tratamientos superficiales Elhco - Electroless Hard Coat
Tratamientos superficiales Elhco - Electroless Hard Coat
Tratamientos superficiales Elhco - Electroless Hard Coat
  • Starting date: 1st January 2021
  • Finishing date: 30th April 2023

  • Participants: Fundación CIDETEC (SPA, project coordinator), Helmholtz-Zentrum Hereon (GER), Fundación Azterlan (SPA), Elsyca NV (BEL), Max Planck Institut fur Eisenfoschung (GER) and ELHCO (SPA).

SUMMARY

One drawback associated to Ultra High Strength Steels (UHSS) coated components is the risk of hydrogen embrittlement (HE) and delayed hydrogen fracture of the part. This problem has been tackled by developing LHE (Low HE) processes and by applying a degassing stage. The standard degassing process is applied equally to the components regardless UHSS or coating composition/morphology. However, it is known that the nature and structure of both the base material and the coating have a great influence in the hydrogen intake and degassing efficiency. Thus, there is much room for improvement if a better understanding of the underlying phenomena of electrochemically deposited corrosion protection layers of UHSS parts on hydrogen degassing is achieved.

As there are no experimental techniques to measure hydrogen content or HE in a specific part of a real component at an industrial environment, modelling and simulation approaches, developed with a strong experimental base, are expected to provide the keys to process improvement.

As such, if a verified model correlating the influence of undesirable layer structures of electrochemically deposited protection layers of UHSS parts on hydrogen degassing was created, the remaining hydrogen concentration in steel parts and the probability for hydrogen embrittlement would be predicted. The industrial objective is to minimize rework and scrap of ultra-high-strength-steel parts and the related environmental impacts.
With its digital approach, H2Free will accelerate materials modelling uptake into European industrial decision making and link all partners to central European materials modelling platforms and activities.

The project brings together a strong consortium composed of 4 outstanding research centres and 2 SMEs with complementary profiles and large expertise in their respective fields, covering the capabilities necessary to carry it out.

One drawback associated to Ultra High Strength Steels (UHSS) coated components is the risk of hydrogen embrittlement (HE) and delayed hydrogen fracture of the part. This problem has been tackled by developing LHE (Low HE) processes and by applying a degassing stage. The standard degassing process is applied equally to the components regardless UHSS or coating composition/morphology. However, it is known that the nature and structure of both the base material and the coating have a great influence in the hydrogen intake and degassing efficiency. Thus, there is much room for improvement if a better understanding of the underlying phenomena of electrochemically deposited corrosion protection layers of UHSS parts on hydrogen degassing is achieved.

As there are no experimental techniques to measure hydrogen content or HE in a specific part of a real component at an industrial environment, modelling and simulation approaches, developed with a strong experimental base, are expected to provide the keys to process improvement.

As such, if a verified model correlating the influence of undesirable layer structures of electrochemically deposited protection layers of UHSS parts on hydrogen degassing was created, the remaining hydrogen concentration in steel parts and the probability for hydrogen embrittlement would be predicted. The industrial objective is to minimize rework and scrap of ultra-high-strength-steel parts and the related environmental impacts.
With its digital approach, H2Free will accelerate materials modelling uptake into European industrial decision making and link all partners to central European materials modelling platforms and activities.

The project brings together a strong consortium composed of 4 outstanding research centres and 2 SMEs with complementary profiles and large expertise in their respective fields, covering the capabilities necessary to carry it out.

OBJECTIVES OF THE PROJECT

The main objective of the H2Free project is to develop a practical guideline for hydrogen degassing of UHS-steels plated with LHE-Zn-Ni, with the aim of saving production costs and allowing Zn-Ni to overtake Cd coatings. The guideline will contain simple rules/formulas to provide criteria to design the degassing process, based on experimental data and on modelling to predict the hydrogen effusion in coated UHSS, the remaining hydrogen concentration in the components and so the probability of hydrogen embrittlement.

For this purpose, the following listed specific objectives will be pursued:

  • To understand the way in which the base materials (UHSS) proposed for the investigation affect the H intake and how their structure affects the H effusion and degassing process once being coated. Such materials will be ranked in terms of H2 embrittlement susceptibility, based in a first approach on bibliography/previous work for all materials proposed in the topic and afterwards on the model predictions and experimental data with the selected 4 UHSS. Then a methodology to rank materials will be developed considering not only the susceptibility to retain H, but also the facility to degas (possibility of operating at lower temperatures, less time needed to degassing). Currently, the aeronautical standards for UHSS only consider one group of UHSS with 23 hours of degassing.

  • To have a better knowledge of the way in which plating parameters (electrical and hydrodynamic) determine the plated layer morphologies, how these morphologies affect the H intake and how this layer morphology affects the H effusion and degassing process. A very complete database will be obtained for the 300M, which is the UHSS most used in landing gear parts. This study will be completed with further data for another 3 representative UHSS.
  • To determine H concentration and permeation parameters in specific local volumes and areas of material and coating such as interfaces, grain boundaries, segregations, etc. These parameters will be correlated with the embrittlement level determined by mechanical testing and fracture surface analysis.
  • To develop and validate a computer-based model to simulate H2 intake and effusion on different base materials (4 UHSS) depending on plating conditions, coating thickness, morphology and degassing conditions. This mathematical tool will allow identifying the remaining H concentration in specific areas of coated parts at which H is more difficult to be eliminated and so the probability for HE, allowing designing with more accuracy the degassing process and so reduce rework, scrap and environmental impact. The model will be transferred and adapted to complex geometries through a 3D electrochemical simulation tool (Elsyca PlatingMaster).
  • To establish a methodology to characterize coated parts (simple verification method to evaluate coating compactness –cracks, pores and grain size- and if it is needed structural phases), applicable on real parts produced in serial production and based on visual and/or colorimetric inspection aided by chemical contrast together with thickness and roughness measurements. This method will allow reworking the parts locally by means of brush plating only in the areas with undesirable layer structures/morphologies.
  • To propose guidelines for an optimal degassing process after Cd or Zn-Ni plating application in view of a reduced H embrittlement risk. The project will provide simple rules/formulas with measures to be taken after UHSS plating and clear criteria for degassing UHSS coated parts that enable a more reliable degassing process (towards zero-retained H strategy). This optimization will allow for a significant reduction of the number of parts that have to be reworked and even scrapped. It also will allow a reduction of the average time needed for degassing that will be adapted to coating characteristics and part geometry.
  • To ensure eco-friendly and economically viable degassing procedures. Simulation will enable eco-design driven solutions. The improvement in the simulation results accuracy will impact on part and process designs in terms of avoiding overcoating the most accessible surfaces and ensuring layer compactness. This will ensure satisfying the minimum effective coating thickness of the least accessible surfaces of the parts with minimum process time and consumption of chemicals. This benefit directly plating process energy consumption, production time and capacity. Furthermore, it also implies the definition of the requirements for more advanced plating tooling equipment that minimizes the risk of incidences for plating and degassing areas with critical geometric features. Another chapter besides productivity and material consumption is related to minimizing rework operations and correct dehydrogenation test costs. The practical rules for the degassing process, defined in the project, will lead to a reduction of costs and energy consumption in comparison to the current standard method. All these benefits are even more relevant in the development of new products, as the cost and lead time required to reach an optimum coating process for new parts will be shortened.
  • To promote dissemination, exploitation, commercialization and contribution to standardization plans, including

    • i) A roadmap to go from TLR 5-6 to TRL 9 after the project.
    • ii) Recommendations about the steps to be performed to trigger new standards on degassing time reduction and to present them to relevant standardization technical committee/s.

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