Inconel 600 Welding Procedure
Inconel 600 or Alloy 600 is a super austenitic Nickel base alloy (Fe-Ni-Cr) used for its high corrosion resistance and creep properties for elevated (High) temperature applications. High nickel presents in the alloy making it immune to chloride stress corrosion cracking and chromium gives general resistance to oxidation at room temperature and high temperature. Being an austenitic microstructure and lack of any precipitation alloying element (e.g. Nb or Ti), Inconel 600 can only be cold hardened. Due to these properties, Inconel 600 is widely used in heaters tube, evaporators tube, condensers & heat exchangers (Tubesheet weld overlaid with Inconel 600).
Inconel 600 mechanical, chemical properties
The UNS number of Inconel 600 is UNS N06600. The ASME Section IX welding P No. for Inconel 600 is 43. The P No. for brazing of Inconel 600 is 111.
The final mechanical properties of Inconel 600 depend on the material condition. For example, cold rolled or hot rolled. The typical tensile strength of Inconel 600 is 80- 100 KSi (550-690 MPa) & Yield strength is 25- 50 KSi (170-345 MPa). The percentage Elongation of Inconel 600 is 35 – 55 and the material hardness is 65-85HB.
Chemical properties of Inconel 600 is given in the below table:
Ni%+ Cb%____ 72.0 minimum
Cr % ____ 14 – to17
Fe% ____ 6 to10
C % ____ 0.15 maximum
Mn% ____ 1.00 maximum
S% ____ 0.015 maximum
Si % ____ 0.50 maximum
Cu% ____ 0.50 maximum
Stick/ SMAW Welding of Inconel 600
Stick Welding or SMAW Welding of Inconel 600 is carried out with SFA/A 5.11- ENiCrFe-2 (Inco Weld A) or ENiCrFe -3 (Inco 182) electrode. ENiCrFe-2 or ENiCrFe -3 Electrode does not require any baking. It is recommended to keep them in a holding oven to avoid the weld porosity issues which can arise when welding Inconel 600 with moist electrodes although. When welding Inconel 600 with SMAW or Stick Welding, extra cleaning between passes is required to remove all slag or inclusions to avoid any welding defects. Although, TIG Welding offers clean weld deposits.
ENiCrFe-2: The weld deposit chemistry made using ENiCrFe-2 contains 70% Ni, 2% Mn,15% Cr, 8% Fe, 2% Nb+Ta, and 1.5 Mo. ENiCrFe-2 electrodes is used for welding jobs from low temperatures to high temperatures up to 1800°F (980°C). Although, for temperatures more than 1500°F [820°C], weld metal deposit by ENiCrFe-2 does not exhibit optimum oxidation resistance and strength.
ENiCrFe-3: This stick welding rod is used for welding of many welding applications ranging from welding of Inconel 600, Carbon steel to stainless steel and weld overlay applications. This rod is also called Inco 182 welding rod.
|Process||Welding ampere||Welding Volts||Welding speed|
|Stick Welding||100- 150||20- 23||170- 210||Reverse||175 max.||–|
|GTAW (TIG)||80 to 130||14- 18||90-120||Straight||175 max.||10 to 15|
TIG/ MIG Welding of Inconel 600
TIG Welding or MIG Welding of Inconel 600 is carried out using TIG/ MIG filler of classification ERNiCrFe-6 or ERNiCr-3 as per AWS A 5.14. Pure argon is used for shielding and purging. Gas purging is mandatory when welding the Inconel 600 materials. Purging is not required for fillet welds but it’s mandatory when welding open root either in butt joints (pipe welding) or T Joints (e.g. weldolet joint). ERNiCr-3 can be used for a maximum application temperature of 1400 °F (760 °C) in a Non-sulfidation environment and 750 °F (400 °C) in a Sulfidation environment.
What is Preheat & Interpass temperature for Inconel 600 Welding?
The maximum allowed interpass for the welding of Inconel 600 shall be limited to 350 °F (175 °C). Preheat temperature shall be ambient temperature only as Inconel 600 is primarily an austenitic material & hence need not be preheated for welding. The heat input when welding Inconel 600 shall be kept to the lowest so that interpass temperature will be easily controlled. A high input will increase the accumulated heat in the weld joint and it will be difficult to control the welding interpass temperature.
Inconel 600 Welding Procedure
Inconel Welding is recommended to weld using TIG or MIG Welding as they offer clean weld deposits. For welding Inconel 600, follow the below steps:
- Preclean the parts before welding.
- Use ERNiCrFe-6 or ERNiCr-3 as per AWS SFA 5.14.
- No preheat is required.
- Follow maximum heat input of 1.2 kJ/ mm.
- Maximum interpass temperature shall be kept below 350 °F (175 °C).
- Perform interpass cleaning when welding with the stick or SMAW Welding.
- Use pure argon for gas shielding and purging with TIG/ MIG Welding.
How to Weld Inconel 600 to Carbon Steel?
Stick Welding or SMAW Welding of Inconel 600 to carbon steel/ mild steel is carried out with AWS SFA/A 5.11- ENiCrFe-2 or ENiCrFe -3 electrode. TIG/ MIG Welding of Inconel 600 to Carbon steel/ Mild steel is made using ERNiCrFe-6 or ERNiCr-3 type filler wire.
How to Weld Inconel 600 to Stainless Steel?
Stick Welding or SMAW Welding of Inconel 600 to Stainless steel is carried out with AWS SFA/A 5.11- ENiCrFe-2 or ENiCrFe -3 electrode. TIG/ MIG Welding of Inconel 600 to stainless steel is made using ERNiCrFe-6 or ERNiCr-3 type filler wire.