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 |
|
|
S32750，SAF2507 |
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.
|
|
630，17-4PH |
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.
|
|
|
631，17-7PH |
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.
|
|
|
632，PH15-7Mo |
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. |
