For Stainless Steel

Stainless Steel Welding Consumables Introduction


1.Parent Material Properties

  Definition: The content of chromium (Cr) in steel liquid > 12% of steel is called stainless steel, the general commercial specification of chromium content of ≧11%
When the content of chromium in steel exceeds 12%, a film of chromium oxide is formed on the surface of the steel to isolate the erosion of the parent material in the environment.

  Stainless steel classification methods are many, the common classification is based on structure types or compositions for classification, related material categories and main uses as shown in the table below

Categores

Composition

Steel Grade

Main Application

Martensite

Fe-Cr

SUS410

Blades, Turbine Blades.

Ferrite

SUS410L / SUS405 / SUS430

Exhaust Accessory, Hot Water Heater, Roofing Material.

Austenite

Fe-Cr-Ni

SUS201 / SUS304 / SUS316

Food/Beverage Equipment, Chemical Apparatus, Nuclear Energy Use.

Duplex Stainless Steel     (Austenite+Ferrite)

SUS329J3L / SUS329J4L

SUS2205

Oil Well Pipes, Chemical Apparatus, Seawater Condenser, Seawater Desalination Plant.

Precipitation Hardening Stainless Steel

SUS630

Blades, Molds, Shafts.

 

 

(1)   Martensite Family:

 

Grade

Features

Martensite Family

403

Turbine & High-Stress Accessory.

410

General Uses.

414

Add Ni for corrosion resistance improvement.

416

Increase P and S for processability improvement.

416Se

Add Se for a better processing surface.

420

Add C for mechanical properties improvement.

420F

Increase P and S for processability improvement.

422

Add Mo, V, and W for better strength and toughness at 649℃.

431

Add Cr and Ni for better corrosion resistance and mechanical property.

440A

Add Cr for corrosion resistance improvement.

440B

Little higher C than 440A for tools, gauges, and bearings Slightly higher C content than 440A, for tools, gauges, bearings.

440C

Carbon content of 440 series of the highest for high hardness, nozzles, bearings.

 

 

(2)Ferrite Family:

 

Grade

Features

Ferrite Family

405

Reduce Cr and add Al to prevent hardening when cooled at high temperatures.

409

Reduce Cr for mainly use in automotive exhaust systems

429

Reduce Cr for better weldability

430

General Use

430F

Add P for processability improvement

430FSe

Add Se for a better processing surface

434

Add Mo for corrosion resistance improvement

436

Add Mo, V, and Ta for corrosion and heat resistances improvement

442

Add Cr for scale resistance improvement

444

Add Mo for corrosion resistance improvement

446

Add Cr for scale resistance improvement

 

 

(3)Austenite Family:

 

Grade

Features

Austenite Family

201

Add N and Mn instead of partial content of Ni for general industrial use such as iron windows, iron doors, beams

202

Add N and Mn instead of partial content of Ni for general industrial use

205

Add N and Mn instead of partial content of Ni for general industrial use

301

Reduce Cr and Ni to increase processing hardening

302

Higher content of C than 304 for general use

302HQ

(UNS S30430)

Add Cu for cold processing improvement

302B

Add Si to increase the scale resistance

303

Add P for processability improvement

303Se

Add Se for a better processing surface

304

Lower content of C better for corrosion resistance

304L

Lower content of C than 304 for corrosion resistance improvement

304LN

Add N and lower C to increase strength and corrosion resistance improvement

304N

Add N to increase strength

305

Add Ni to reduce processing hardening

308

Higher content of Cr and Ni than 304 mainly for welding

309

Add Cr and Ni to increase heat and oxidation resistances

309S

Lower content of P than 309

310

Add more Cr and Ni to significantly improve heat resistance

310S

Add more Cr and Ni to significantly improve heat and creep resistances

314

Add Si for excellent heat resistance

316

Add Mo to increase pitting corrosion resistance

316L

Reduce C for better weldability and corrosion resistance

316LN

Reduce C and add N to increase strength

317

Add more Mo and Cr for excellent corrosion resistance

317L

Reduce C for better weldability and corrosion resistance than 317

321

Add Ti to prevent carbide precipitation and increase corrosion resistance

329

Add Cr and Ni similar to duplex property, reduce stress corrosion cracking resistance

347

Add Nb and Ta to prevent carbide precipitation and increase corrosion resistance

348

Limitation of Ta and Co for nuclear energy plant application

384

Add Ni to reduce processing hardening

 

 

 

(4)Duplex Stainless Steel (Austenite + Ferrite) Family

 

Grade

Features

Duplex Stainless Steel  Family


S32900 SUS329J1L

PRE (%) about 29.5% the 1st Duplex Stainless Steel 

S31803 SUS329J3L

SAF2205

PRE (%) about 33.6% the 2nd Duplex Stainless Steel as more general use

S31260 SUS329J4L

PRE (%) about 36.6% the 2nd Duplex Stainless Steel

S32550

PRE (%) about 40.6% the 3rd Duplex Stainless Steel so-called Super-duplex Stainless Steel

S32750SAF2507

PRE (%) about 40.7% the 3rd Duplex Stainless Steel so-called Super-duplex Stainless Steel

*RE(%)= %Cr+3.3%Mo+16%N

The highest PRE the best pitting corrosion resistance.

 

 

(5)Precipitation Hardening Stainless Steel Family:

 

Grade

Features

Precipitation Hardening Stainless Steel Family

15-5PH

Content 15%Cr - 5%Ni as the precipitation hardening type of Martensitic structure for aerospace industry.

63017-4PH

Content 17%Cr - 4%Ni - 4%Cu - 0.4%Nb+Ta as the precipitation hardening type of Martensitic structure for aerospace, biomedical, petrochemical, food and beverage, and papermaking industries.

63117-7PH

Content 17%Cr - 7%Ni - 1%Al as the precipitation hardening type of semi-austenitic structure for aerospace, biomedical, chemical, petrochemical, papermaking, and metal processing industries.

632PH15-7Mo

Content 15%Cr - 7%Ni - 2%Mo - 1%Al as the precipitation hardening type of semi-austenitic structure for spring, medical care, oil drilling industries.

17-10P

Content 17%Cr + 10%Ni as the precipitation hardening type of austenitic structure for flanges, molds, and tools.

 

 

 

2.Welding method and characteristics

Structural category

Welding characteristics and precausion

Martensite

  The structure characteristics is hard and brittle, especially in the heat-affected areas caused by the high sensitivity of cracking; the temperature management needs to be implemented.

Ferrite

  The temperature of the weld is prone to brittleness at 370-925℃ for a long time, so as to avoid excessive overhigh temperature between the welds.

Austenite

  The temperature of the weld is prone to sensitivity at 450-850℃ for a long time, resulting in chromium carbide precipitation and reducing corrosion resistance

Duplex Stainless Steel Family

  The temperature of the weld is prone to sensitivity at 300-900℃ for a long time, the heat input and weld temperature should not be too high.

Precipitation Hardening Stainless Steel

  General selection of 308 series or 309 series or the same type of steel material; When considering PWHT and cracking sensitivity, consider using Ni-Cr system or NiCrMo system for use.

 

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