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master class DSS Raymond Cordewener M. C. Escher

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master class DSS

Raymond Cordewener

M. C. Escher

AcknowledgementThere is very good literature available.

A lot is just available on the internet

Jacques Charles

Jan Olof Nilsson

IMOA

Nickel Institute

Outokumpu

Arcelor Mital

Sandvik

Cerec-Antonius Dominik Bruch and Brück® Group

In this master class I make use of this information With this statement refer to these publications!

Agenda• Introduction of the Duplex Stainless Steel family or grades

• What makes DSS so special?

• Mechanical Properties

• Do's and Don'ts for Duplex – Cutting of Duplex

– Welding

– Cold Forming

– Hot Forming

– Heat Treatment

• Temperature control

• Temperature Range of using Duplex

• Welding DSS to Carbon Steel

• Who is afraid of Sigma Phase

• Do's and Don't for Duplex– Forging

– NDE techniques

– Surface treatment

Agenda

Introduction DSS grades

Introduction DSS gradesFor duplex the aim is to have a phase balance is

50/50 - austenite / ferrite

• Ni eq = Ni + 0.5 Mn + 0.3 Cu + 25 N + 30 C

• Cr eq = Cr + 1.5 Mo + 0.75 W

Introduction DSS grades

Introduction DSS grades• Influence of Nickel on the Stainless Steel

http://www.imoa.info/_files/stainless_steel/Duplex_Stainless_Steel_2d_Edition.pdf

Introduction DSS grades• Influence of Nickel on the Stainless Steel

http://www.imoa.info/_files/stainless_steel/Duplex_Stainless_Steel_2d_Edition.pdf

Introduction DSS grades• Influence of Nitrogen in DSS

Higher Nitrogen additions

stabilize the duplex

microstructure (HAZ particularly)

Use 22 Cr duplex with 0.17 N

Use 25 Cr duplex with 0.25 N

Nitrogen additions improve the

corrosion resistance (pitting,

crevice)

800

1000

1200

1400

0 5 10 1530 25 20 15

% Ni% Cr

L°C °F

2550

2200

1800

1500

[N]

A1 B1

A0 B0

O1

O0

L +

L + L +

What makes DSS so special?

Cost Saving:

High Strength

Good Corrosion Properties

Relatively easy to fabricate

High Strength

GradeRp0.2@ RT[MPa]

Rp0.2@ 100[MPa]

Rp0.2@ 200[MPa]

@ RT[MPa]

@ 100[MPa]

@ 200[MPa]

@ RT[MPa]

@ 100[MPa]

@ 200[MPa]

Design stress in Europe EN

Design stress USA ASME VIII-1

2101 450 380 330 270 250 220 185 180 170

2304 400 330 280 260 220 185 170 160 150

2205 460 360 315 265 240 210 175 175 160

2507 530 450 400 300 300 265 225 225 205

High Strength

Good Corrosion Properties

Good Corrosion Properties

Mechanical PropertiesFamily of Duplex Steels

Lean Duplex 2101

Lean Duplex 2202

Duplex 2304

Standard Duplex 2205

Super Duplex 2507

Hyper Duplex 2707 HD

Hyper Duplex 3207

Mechanical PropertiesInfluences on Mechanical properties:

Forming Direction

Thickness (3D effect)

Chemical composition

Cleanliness of the duplex S, B and more

Mg, Pb and a long list

Morphology

Machining

General information:

More power is required

More time is requiredTurning speed 2507 is 1/3 of speed 2101

Turning speed 2101 is 25% faster than 316L

Not easy with low roughness

Machining has influence on FN reading

Dry turning/milling is possible

Machining

Do

Use a sturdy machine

Use dedicated tool-bits and drills

Plasma-Cutting

General information:

Possible with small changes of parameters

Cut is not as good as on SS

Plasma-Cutting

Don’t

Neglect sparks made on plate surface. At surface you will have full ferritic SS and NO duplex anymore. You need to polish them clean.

Plasma-Cutting

Do

Understand that you generate a HAZ during cutting, which you have to grind off approx. 1 mm (check hardness)

Use Personal Protection + Local fume extraction for the fumes

Take care of good earthen

Welding

Welding

CORROSION RESISTANCE

TOUGHNESSAT LOW TEMPERATURE

CONTROL OF FERRITEin HAZ < 70 %in welds 20-40 % SAW, SMAW

25-60 % TIG, MIG, PLASMA

CONTROL OF OXYGEN CONTENT

SAW with appropriate flux basicity

CONTROL OF HYDROGEN CONTENTDegasing of welding consummables...

No hydrogen in shielding gas

CONTROL OF NITROGEN LEVEL

CONTROL OF THERMAL CYCLEHeat input adapted to plate thickness weld geometry

Requirements

Welding

General information:

Welding is not that different to SSProcesses like SAW, SMAW, FCAW, GTAW, GMAW,

PGMAW are all possible.

The Welder must take very good care and understand he is welding 2 phase material

Welding

General information:

The Welding Engineer must choose the correct welding consumable depending on yes/no solution annealing.Matching of Over-Alloyed composition

The choice has influence on solution annealing temperature

Weldingh

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Welding

Don’t

Strike the electrode in the Weld-edge or on the surface

Re-melt surfaces by TIG for smoothing the surface

Re-use welding flux more than 2 times

Welding

Do

Understand that every stop (crater) is a small crack and has to be removed by grinding

I prefer welders who can do PT-level 0 them selves

I don’t choose welder who think they are too good to perform grinding

Cold Forming

General information:

Due to high yield propertiesyou are working almost twice the thickness in SS.

If there is a weld-seam in theproduct you must take very good care of welding. (high impact values)

Cold Forming

Deepdrawing

Cold Forming

Don’t

Press with Carbon Steel tools on final products (iron contamination)

Cold Forming

Don’t

Perform flame straightening without final heat treatment

Don’t allow construction workers to perform welding.

Cold Forming

Don’t

Perform flame straightening without final heat treatment

Don’t allow construction workers to perform welding.

Cold Forming

Do

Take care of surface treatment

Perform Solution Annealing if deformation grade is over 10% and products are containing chemicals or are for sea-water application

Hot Forming

General Information:

For Hot Pressing you need to understand Duplex, heat treatment and all the phases you need to avoid.

The Hot pressing is easy if you understand all these points.

Hot Forming

Don’t

Start pressing below 900 degrees

Think you have enough time based on Sigma nose

Hot Forming

Sigma

Forming shifts the nose to the left.

Hot Forming

Do

Take care of correct temperature control during Hot Pressing

Take care of support of the product

Take care of proper surface treatment

(Sand) blasting and Pickling is recommended

Perform process in short period

Hot Forming

Do

Use Lubricants

Use Pyrometers to have an understanding of temperature during pressing

Heat Treatment

General Information

ProductTest plates

Design codeInternal material data sheetFP / FIP / QPMaterial certificatesStandardsMill information

FurnacesGas fired- furnaceElectro-furnaceThermocouplesPyrometerCooling mediumPlotters

Heat treated productHeat treated test platesHeat treatment chartHeat--treatment certificateExperiences

Heat TreatmentGeneral Information

In literature you find the risk of Sigma phase during welding due to high heat input

During heating up we will cross all phases and all phases needs to be dissolved again Solution annealing temperature is depending on chemical composition

of base-material and weld-material

Soaking time depending on thickness

The most important factor is the quenching In most cases this is not measured

Heat TreatmentExample from a graph including the quenching

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

0:00:00 4:48:00 9:36:00 14:24:00 19:12:00 24:00:00 28:48:00

Fühler 1 (außen)

Fühler 2 (100 mm)

Fühler 3 (100 mm mitFehler)

Dauer [h:m:s]

Heat TreatmentFEM and 3D Metallurgy

-70

-60

-50

-40

-30

-20

-10

0

0

200

400

600

800

1000

1200

0 200 400 600 800 1000 1200 1400 1600

55x100mm_quenchsim

55x127mm_quenchsim

105x127mm_quenchsim

coolingrate 55x100mm

coolingrate 55x127mm

coolingrate 105x127

Heat TreatmentFEM and 3D Metallurgy

300

400

500

600

700

800

900

1000

1100

0.1 1 10 100 1000 10000 100000 1000000

Tem

pe

ratu

re (

°C)

log time (min)

SIGMA(0,1%)

CHI(0,1%)

LAVES(0,1%)

ALPHA_CR(0,1%)

M2(C,N)(0,1%)

M(C,N)(0,1%)

M23C6(0,1%)

M7C3(0,1%)

M6C(0,1%)

1000°C/min

200°C/min

100°C/min

50°C/min

10°C/min

Temperature ControlTry to understand the type of controller

o By means of temperature sticks.

o By means of Pyrometer.

o By means of thermocouples.

o By means of contact thermometer.

o All have their own temperature-range.

o Welded thermocouple wire

Temperature ControlTry to understand the controller and the furnace

o Datalogging is very important to analyse

o Study the Heating and Cooling rate and not temperature only

Temperature Range DSS

• Guess

10000 (Time - sec.)

S 31803

200

400

600

800

1000

10

°C

S 32304 S 32550

S 32520 S 32750 S 32760

100 1000

390

750

1110

1470

1890

°F

Temperature Range DSS

• Guess!

• 250°C

10000 (Time - sec.)

S 31803

200

400

600

800

1000

10

°C

S 32304 S 32550

S 32520 S 32750 S 32760

100 1000

390

750

1110

1470

1890

°F

Welding DSS to Carbon SteelCombination is welded with 309L

Who is afraid of sigma phase?

Who is afraid of sigma phase?

• You should be

800 (116)

600 ( 87)

400 ( 58)

200 ( 29)

A % KCV HV5

25 150 420

20 120 380

15 90 340

10 60 300

5 30 260

Y.S. Rp 0.2 UTS (UTS/Rm)

10 20 30 40 % 50

MPa (KSI)

Can we avoid Sigma phase?• Depending on DSS grade

• Depending on Thickness

300

400

500

600

700

800

900

1000

1100

0.1 1 10 100 1000 10000 100000 1000000

Tem

pe

ratu

re (

°C)

log time (min)

SIGMA(0,1%)

CHI(0,1%)

LAVES(0,1%)

ALPHA_CR(0,1%)

M2(C,N)(0,1%)

M(C,N)(0,1%)

M23C6(0,1%)

M7C3(0,1%)

M6C(0,1%)

1000°C/min

200°C/min

100°C/min

50°C/min

10°C/min

Can we avoid Sigma phase?

Can we avoid Sigma phase?

Can we avoid Sigma phase?

Can we avoid Sigma phase?

Can we avoid Sigma phase?

300

400

500

600

700

800

900

1000

1100

0.1 1 10 100 1000 10000 100000 1000000

Tem

pe

ratu

re (

°C)

log time (min)

SIGMA(0,1%)

CHI(0,1%)

LAVES(0,1%)

ALPHA_CR(0,1%)

M2(C,N)(0,1%)

M(C,N)(0,1%)

M23C6(0,1%)

M7C3(0,1%)

M6C(0,5%)

1000°C/min

200°C/min

100°C/min

50°C/min

10°C/min

SIGMA(5%)

CHI(5%)

SIGMA(0,5%)

SIGMA(1%)

SIGMA(2%)

CHI(0,5%)

CHI(1%)

CHI(2%)

LAVES(0,5%)

LAVES(1%)

LAVES(2%)

M2(C,N)(0,5%)

M2(C,N)(1%)

360°C/min

4°C/min

Can we avoid Sigma phase?

300

400

500

600

700

800

900

1000

1100

0.1 1 10 100 1000 10000 100000 1000000

Tem

pe

ratu

re (

°C)

log time (min)

SIGMA(2%)

CHI(2%)

LAVES(2%)

ALPHA_CR(2%)

M2(C,N)(2%)

M(C,N)(2%)

M23C6(2%)

M7C3(2%)

1000°C/min

200°C/min

100°C/min

50°C/min

10°C/min

Forging of DSSGeneral Information

You will need extra force

Material is very soft at high temperature (1.200-1.250 °C)

Like with any Hot Forming, Solution heat treatment is essential

Temperature control is essential

Do

Use sturdy presses equipment

Understand that Forging ratio is vital

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120

Distance to surface [mm]

Imp

act

str

en

gth

[J]

melt B tangential

melt B radial

melt A tangential

melt A radial

min. value [NORSOK]

Forging

Forging

Don’t

Forge at low temperature

NDEGeneral Information:

DPE

UT of weld-seams over 50 mm

TOFD is performed and is known to show 10% more defects.

MPE is possible

RT of weld-seams up to 50 mm

Measuring FN with ferritscope

NDE

Do

Properly clean the surface before performing any NDE

Select the right film for RT

Practice with Ferritscope if you need to use it. Handle gently

NDE

Don’t

Perform polishing when defects are found

Use grinding or milling

Allow anybody grinding near to the testing area

Surface Treatment

General Information:

Polishing is possible but takes very long

Electro polishing is possible by experts

Pickling is not easy due to good pickling resistance of DSS

Surface Treatment

Do

Perform Pickling on formed products which are not machined are advised.

Perform Sandblasting on scaled surfaces from solution annealing, before pickling

Check surfaces on spatters and remove them by grinding before pickling.

Surface Treatment

Don’t

Use grit for blasting

Use used sand/ korrund for blasting

Pickle scaled surfaces after Solution Annealing. This takes days.

Thank You very MuchFor questions:

Raymond Cordewener

[email protected]

[email protected]

Tel: +49 6893 84184

Mobile: +31 653551792