Oberflächenhärten von Armaturenkomponenten aus Edelstählen, Nickelbasis- und Titan-Werkstoffen

DIAM 2021, Dr. Holger Selg, Sales Director bei Expanite GmbH

Motivation

The problems

Untreated stainless steel surface (ball, shaft,…) suffers from…

9h June 2015 AT n° CET0111600_PV_01_a Page 20/23

Final

Figure 15 : Figure 16 : Worn surface on reference stainless steel plane – test #3.

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Longueur = 3.00 mm Pt = 144 µm Echelle = 200 µm

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Profondeur maximum 135 µm Surface du trou 153411 µm²

Hauteur maximum 1.59 µm

…wear!

…galling!

…cavitation & erosion!

The solution - surface hardening!

Surface hardening -> 10x surface hardness

• Improving hardness – and thereby wear, galling and corrosion resistance beyond what the market previously has seen

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Micrographs & hardness profile of part in AISI316

Surface hardening -> 125x wear resistance*

9h June 2015 AT n° CET0111600_PV_01_a Page 21/23

Final

“SuperExpanite” tests: worn plane surfaces

Figure 17 : Worn surface on “SuperExpanite” plane – test #1.

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Longueur = 3.99 mm Pt = 4.19 µm Echelle = 10.0 µm

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Profondeur maximum 3.38 µm Surface du trou 664 µm²

Hauteur maximum 0.306 µm Surface repoussée 2.39 µm²

Un treated reference

SuperExpanite hardened

ASTM G133 wear test on AISI316Sliding distance: 100m, 25N

9h June 2015 AT n° CET0111600_PV_01_a Page 20/23

Final

Figure 15 : Figure 16 : Worn surface on reference stainless steel plane – test #3.

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Profondeur maximum 135 µm Surface du trou 153411 µm²

Hauteur maximum 1.59 µm

*Conclusion: 125 times less wear on SuperExpanite treated plane surface in experimental set-up

Surface hardening -> NO galling

OwnerofBudLabs:“ ..hasneverseenanythingperformsowellon316inhis15yearsoftribologytesting”

Untreatedvs.untreated

34bar 68bar 138bar2758bar 344bar 138bar

SuperExpanitevs.SuperExpanite

Aboveyieldstrength!

ASTM G98 galling test on AISI316

OwnerofBudLabs:“ ..hasneverseenanythingperformsowellon316inhis15yearsoftribologytesting”

Untreatedvs.untreated

34bar 68bar 138bar2758bar 344bar 138bar

SuperExpanitevs.SuperExpanite

Aboveyieldstrength!

OwnerofBudLabs:“ ..hasneverseenanythingperformsowellon316inhis15yearsoftribologytesting”

Untreatedvs.untreated

34bar 68bar 138bar2758bar 344bar 138bar

SuperExpanitevs.SuperExpanite

Aboveyieldstrength!

Surface hardening -> cavitation & erosion

Surface hardening -> un-seen corrosion resistance

Electrochemical pitting corrosion tests

Conclusion: superior performance over commonly known processes – and compared to untreated material

What is Expanite?A technology

= process/recipe

= time + temperature + pressure + gas flow + surface physics & chemistry in a furnace

=a gas-based diffusion process

Example with stainless steel:

Product portfolio

ExpaniteHigh-T with nitrogen (N2) or argon (Ar) cooling

ExpaniteHard-Ti

ExpaniteLow-T with nitro-carburizing (N/C) or carburizing (C)

SuperExpanite = ExpaniteHigh-T + ExpaniteLow-T

Product portfolio – a closer look at ExpaniteHigh-T

ExpaniteHigh-T with nitrogen (N2) or argon (Ar) cooling

The ExpaniteHigh-T process

• High temperature vacuum process: 1000-1200C – fast gas quench with N2 or Ar

• Adds nitrogen during process

• Can be used for:

• Austenitic & Duplex alloys in combination with ExpaniteLow-T

• Martensitic & Ferritic alloys as standalone or in combination with ExpaniteLow-T

• Surface/core hardness: 250-900 HV depending on alloy; lowest on austenitic & highest on martensitic stainless steel

• Case depth: 200-1000µm

Transgranular

Cellular

Grain Boundary

Cr2N

g

c

h

ExpaniteHigh-T

Nitrogen in solid solution

Transgranular

Cellular

Grain Boundary

Cr2N

g

c

h

ExpaniteHigh-T

Critical range!!ExpaniteHigh-T applies special gas quench for high interstitial contents

High pressure N2

quench can impair the corrosion resistance!!

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0 0.4 0.8 1.2 1.6 2

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ess

[H

V0

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Treatment: ExpaniteHigh-TCase Depth High-T: 0.55 mmSurface hardness: 750 HV0.3

12.5Cr-0.12C-(1.5Mn+1.0Si max)

ExpaniteHigh-T process – martensitic example

Product portfolio – a closer look at ExpaniteLow-T

ExpaniteLow-T with nitro-carburizing (N/C) or carburizing (C)

The ExpaniteLow-T process

• Low-temperature gas process: 380-490°C

• Adds nitrogen & carbon or carbon only in solid solution – Expanded Austenite

• Can be used for:

• Austenitic, Duplex, Martensitic & Ferritic alloys in combination with ExpaniteHigh-T -> SuperExpanite

• Generally not applicable standalone.

• Surface hardness: 1000-1500 HV

• Case depth: 5-40µm

N + Cor

C only

Up to 35-40µm

Up to 1500HV

The ExpaniteLow-T process, schematically

NC

C

Product portfolio – a closer look at SuperExpanite

SuperExpanite = ExpaniteHigh-T + ExpaniteLow-T

SuperExpanite

PA 2011 70208 patent

+

ExpaniteHigh-T ExpaniteLow-T

SuperExpanite = ExpaniteHigh-T + ExpaniteLow-T

Low-T

High-T

duplex

N

Even stronger (load bearing) plus extreme corrosion resistance!

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N + Cor

C only

The ExpaniteHard-Ti Process

• Diffusion-based process

• Applicable to Ti-G5 (G2)

• Surface hardness: ca. 1000 HV

• Case depth: 10-50µm

• No Ti-nitrides – no golden colour!

• Post-polishing possible

The ExpaniteHard-Ti Process

Ti-G5 (Ti-6Al-4V), treatment: ExpaniteHard-Ti

The ExpaniteHard-Ti Process

Ti-G5 (Ti-6Al-4V), ASTM G-133 wear test; treatment: ExpaniteHard-Ti

About Expanite

Expanite - from research to business in a decade!

• Expanite was founded in 2010 by

• Prof. Marcel A.J. Somers

• Ph.D. Thomas L. Christiansen

• Ph.D. Thomas Strabo Hummelshøj

…but development goes back to 2000!

• First major customer early 2012

• Company culture driven by being a game-changer on the following parameters

• Speed

• Tailoring

• Cleanliness

• On-site

University anno 2009

Expanite in Denmark ultimo 2012

Expanite as of 2021

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Total realized sales 6 per. Mov. Avg. (Total realized sales)

• Facilities in:

• Denmark: Hillerød (HQ, R&D & Treatment facility)

• USA: Cleveland, Ohio (Licensee & Treatment facility)

• Germany: Stuttgart (Treatment facility)

• China: Shanghai (Licensee & Treatment facility)

• Korea (Licensee & Treatment facility)

• 1-2 extensions planned for 2021/2022

• +60% year-on-year growth since 2013

• Approx. 30 employees

• Strong owners with the ambition of growing the company further

Customer cases – 4 examples

Case no. 1 – ball valve• What: ball used in ball valves

• Parts are made in AISI/SUS316 and then hardened by Expanite (SuperExpanite 20µm & 1200HV)

• Expanite solution replaced conventional Carburizing process

• Benefits:

• Better corrosion resistance

• Better wear-resistance

• More competitive

• Faster lead-times

[de.wikipedia.org/wiki/kugelhahn]

Case no. 2 – hygienic valve• What: valve part used in food industry

• Parts are made in AISI/SUS316 and then hardened by Expanite (SuperExpanite 20µm & 1200HV)

• Expanite solution replaced hard-chrome plating and Carburizing process

• Benefits:

• Significant improvement in corrosion resistance

• Significant price reduction

• Lead-times down to 3 working days!

Case no. 3 – valve seat/plate• What: valve seat/plates in gasoline high-pressure

(300bar) pump

• Parts are made in AISI/SUS420 (X46Cr13) – new solution with ExpaniteHigh-T (core hardness min. 600HV10, surface hardness 750HV1 +/-50HV1)

• Expanite solution replaced conventional heat treatmentso pump pressure could be increased, biofuel and less pure fuels could be allowed

• Benefits:

• Better corrosion resistance

• Better wear resistance

• Simplified logistics; identical hardening process available in Europe and Asia

ExpaniteHigh-T vs. vacuum hardening – AISI 420

ExpaniteHigh-T hardened, 120h salt spray

vacuum hardened, 120h salt spray

Case no. 4 – shaft• What: shaft from different types of valves

• Parts are made in Inconel/Monel and then hardened by Expanite (ExpaniteLow-T 10µm, ca. 1000HV)

• Expanite solution on Inconel/Monel replaced coatings

• Benefits:

• No spalling!

• No change in coefficient of thermal expansion

• Significant cost reductions!

• Faster lead times

Summary

What can Expanite be used for…

• Generally increase wear, galling or corrosion resistance of stainless steel and titanium!

• More specifically for austenitic and duplex stainless steel:

• Replace known processes such as Kolsterising® from Bodycote or NV Pionite® from Air Water Inc. Typical outcome; faster lead-time, cost reduction and improved corrosion resistance.

• Replace hard-chrome plating/coatings. Typically outcome; replace the coatings with diffusion -> no issues with spalling & in-homogenous layers, better environmental compliance.

• Replace plasma nitriding. Typically outcome; improved corrosion resistance.

• More specifically for ferritic and martensitic stainless steel:

• Replace conventional heat treatment / vacuum hardening. Typically outcome; significant increase in wear and corrosion resistance.

• Replace hard-chrome plating/coatings. Typically outcome; replace the coatings with diffusion -> no issues with spalling & in-homogenous layers, better environmental compliance.

Thank you – see you in Foyer, booth 5a

www.expanite.com