Wave Form Controlled Technology

GMAW PulsePower ModeRapid Arc

STT

Agenda

1. Introduction2. STT processa) Background currentb) Initial shortingc) Pinch currentd) Secont current reductione) Peak currentf) Tailout3. STT visualization4. STT settings and guidelines5. Application - austenitic stainless. Cr-Mo low alloyed6. STT vs. TIG, austenitic stainless, welding time7. Comparing STT to CV, quality8. Welding fumes9. Possible applications10. Summary benefits11. FCW for austenitic & duplex stainless

Introduction

Arc voltage/Welding current

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3550 100 150 200 250 300 350

Short arc Globular Transfer

Spray arc

ROOT

Fill

Conventional CV

SG2 1.0mm 80/20 MIX-gas

SG2 1.0mm 80/20 MIX-gas

Popular but..limitations and clear disadvantagesPopular but..limitations and clear disadvantages

Alternatives

Arc voltage/Welding current

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5

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3550 100 150 200 250 300 350

STT

Pulse

Pulse / Spray

ROOT

Fill

Wave Form Controlled Alternatives

Power Mode RapidArc

Lincoln Electric Alternatives to offerLincoln Electric Alternatives to offer

STT Process

STT

STT principle

Overal heat input (wetting)

Overal heat veral heat input (wetting)input (wetting)

Reason for lower spatter in STT

Reason for lower Reason for lower spatter in STTspatter in STT

Good fusion and setting of the proper arc length

Good fusion and Good fusion and setting of the setting of the proper arc lengthproper arc length

Movie

STT Process

Background current Arc current level prior to

shorting to the weld pool. Contributes to the overall heat

input Keeps arc lit

Background current (T0 - T1 ): This is the current level of the arc prior to shorting to the weld pool. It is a steady-state current level, between 50 and 100 A

STT Process

Initial Shorting Response to the arc voltage detector

sensing that the arc has shorted Current is reduced even further at

actual ball/weld puddle contact Extremely low current promotes ball

wetting instead of repelling Reason for lower spatter in STT

Ball time: When the electrode initially shorts (at the background current), the "arc voltage" detector provides a signal that the "arc" is shorted. The background current is futher reduced to 10 A for approxiametly 0.75 milliseconds. This time interval is referred to as the ball time.

STT Process

Pinch Current High current is applied immediately after

the initial short Current increases, causing the molten

droplet to separate from the electrode STT electronically calculates when

droplet separation is to occur and reduces the current before this happens, eliminating the explosive spatter.

Pinch mode (T2 - T3 ): Following the ball time, a high current is applied to the shorted electrode in the form of an increasing, dual - slope ramp. This accelerates the transfer of molten metal from the electrode to the weld pool by applying electronic pinch forces.

STT Process

Second Current Reduction Current is quickly reduced before

electrode separates, eliminating spatter

STT circuitry re-establishes the welding arc at a low current level

The dv/dt calculation: This calculation is included within the pinch mode. It is the calculation of the rate of change of the shorted electrode voltage vs . time. When this calculation indicates that a specific dv/dt value has been attained, indicating that fuse separation is about to occur, the current is reduced to 50 A in microseconds. (Note, this event occurs before the shorted electrode separates. T4 indicates the separation has occurred, but at a low current.

STT Process

Peak Current High current is applied immediately

after the arc is reestablished Arc is momentarily broadened,

producing high heating of the plate, insuring good fusion and setting the proper arc length

Plasma boost (T5 - T6 ): This mode follows immediately the separation of the electrode from the weld pool. It is the period of high arc current where the electrode is quickly "melted back." (The geometry of the melted electrode at this point is very irregular.)

STT Process

Tailout Current is reduced from peak

to background level Reduces agitation of the weld

puddle This control is a coarse heat

controlPlasma (T6 - T7 ): This is the period of the cycle where the arc current is reduced from plasma boost to the background current level.

movie

Movie

Peak & Background Current

Back ground = WettingHighLow

Peak current = arc pressure & length

Peak currentProviding the energy to set the arc length.Setting according wire diameter and composition.Pressure in both ways; wire and weld bead.

Back ground currentProviding the overall heatMore or less wetting.Most used control on the STT.

Tail outIn the same way as backgroundTo be use with high travel speedAutomation not for pipe welding

STT settings

Application; Stainless preparation

Tape Tack weld with bar Application:Pipe diameter 10 x 8 mmPosition: G3Material: AISI 316L

Backing gas: 95%Ar 5%N2

60

3mm

Preparation; Stainless

Application Stainless pipe

STT RootLNM 316LSI 1,0mmGas: Ar + 2%CO2Peak 270ABackground 80AWFS 168/minPosition 3GD

PULSE FillLNM316LSI 1,0mmGas: Ar + 2%Co222V, 175AmpPosition 3GU (!)

Pulse CAPLNM316LSI 1,0mmGas Ar + 2%CO222 V, 175AmpsPosition 3GU

Application: Stainless Root Pass

Welding stainless Example 7

Cor a Rosta wires are available in most used grades and increased productivity justifies the move to premium quality wires!!!

Cor a Rosta

Example 7

Example 7

Overmaching corrosion resistance

Bead# Method, wire

d, mm I, A U, V Gas Current, polarity

Welding Speed, mm/sek

HI kJ/mm

Remark

1 136, Cor a- Arosta 316L

1,2 155 24 M21 DC+ 5,5-6 0,5

2 -n 136, Cor- a - Rosta 316L

1,2 182 26 M21 DC+ 5,5-6 0,65

12

nn-1

10 mm

LNB

Gates for shipbuilding

PA, 10 mm thick palte, gap 3-4mm, root 1,5, beveling V60

Application: Pipe welding

Application:Pipe diameter 6 x 10mmPosition: G3(D)Material: X42 60

3mm

STT RootSupra MIG 1,0mmGas: Ar + 20%CO2Peak 280ABackground 70AWFS 148/minPosition 3GD

FillOutershield 71E-H 1,2mmGas: 80%Ar 20%Co226V, 215AmpPosition 3GU

CAPOutershield 71E-H 1,2mmGas Ar + 20%CO226 V, 215AmpsPosition 3GU

Application; Steel Root Pass

Setting STT Procedures

STT Welding Parameter Guideline & Joint Configuration Applicable for Un-, Low, & High Alloyed Materials (wire 1.0 mm)

Wall Thickness Welding Position1G / PA (Rotating) 5G Down / PG

Wire Feed Speed Peak Current Backgrond Current

< 3.5 mm

>3.5 mm

Wall Thickness Peak Current

330-360

Wire Feed Speed

8 mm 260-270 65-85 360-420

< 8 mm 260-270 55-65

Gas Selection

Mild & Low Alloyed Steel

Regular 3xx Stainless Steel

(Super) Duplex Stainless Steel

Fully Austenitic Stainless Steel Nickel Alloys

Ar + 20% CO2 ++ - - - -Ar + 20% CO2 + He + - - - -Ar + 2% CO2 - ++ + + -Ar + 28% He + 2%CO2 - + * ++ ++ -Ar + 30% He - - - - +Ar + 28% He + 2%H2 - - - - ++

Backing gasAr (+) + ++ + +N2 (+) + ++ + +N2 + 5%H2 - ++ - ++ ++

++ First option+ Second option

(+) Optional

-Not recommended

* LSW06/AvdS-DR

Shielding & Backing Gas Selection Table

Recommended when wall thickness > 6 mm

Procedure Comparison

Material 1.4462 (Duplex) Material 1.4462 (Duplex)Welding Position 1G Rotating Welding Position 1G RotatingPipe Diameter 25" Pipe Diameter 25"

Consumable LNM 4462 Consumable LNT 4462Classification G 22 9 3 N L Classification W 22 9 3 N LDiameter 1,2 mm Diameter 2,4 mmShielding gas 98% Ar + 2% CO2 Shielding gas 100%Flow 13 l/min Flow 8 l/minBacking gas 100% Ar Backing gas 100% ArStick-out 12 mm Stick-out --Peak Current 280 A Current 90 ABackground Current 80 AArc voltage Arc voltage 11-13 VWire Feed Speed 100 "/min Wire Feed Speed --Welding Time 6 minutes Welding Time 22 minutes

Procedure Comparison

GMAW-STT GTAW

25 mm 25 mm

3-4 mm 3-4 mm

Low Spatter, Defect Free Rootpass

Welding Fume

Solid wire (MIG/MAG, TIG & STT)

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Welding current (A)

STT: 50% reduction in fume emission versus conventional GMAW

Industry Segments

Markets where STT can be appliedOil & Gas Industry

Cross Country Pipelines

Power Generation

Chemical Industry

Pulp & Paper Industry

Food & Dairy Industry

Base materials

Applications with the STT processPipe Root-pass WeldingMild- & Fine Grained SteelLow Alloyed SteelCreep Resistant Steel (qualified and certified in

Poland)Standard 3xx-series Stainless SteelFully Austenitic Stainless Steel(Super)Duplex Stainless SteelNickel Alloys

STT advantages

Full electronically controlled arc.No risk of cold fusion.Different wires and gasses are applicable.Extremely low spatterReduced smoke 4X faster compared to TIG weldingLarge ligament (5.5mm)

The premium root pass processThe premium root pass process

Thank youksadurski@lincolnelectric.eu +48746461155

Wave Form Controlled TechnologyAgenda IntroductionAlternativesSTT ProcessSTT STT ProcessSTT ProcessSTT ProcessSTT ProcessSTT ProcessSTT ProcessmovieMoviePeak & Background CurrentApplication; Stainless preparationApplication Stainless pipeWelding stainlessExample 7Example 720. diaExample 7Application: Pipe weldingSetting STT ProceduresGas Selection Procedure Comparison Low Spatter, Defect Free RootpassWelding Fume Industry SegmentsBase materialsSTT advantages