4130 Preheat and Interpass 2

[ZHA]

Hello All,

We have a job of A519 type 4130 material per ASME B31.3 having thicknesses ranging from 0.344" - 1.88". 4130 material is unclassified per ASME B31.3.

I am starting to weld a PQR for 4130 material
- Can anyone tell me what is the preheat and interpass temperature for A519 Type 4130 material?
- Is preheat required for all thicknesses?
- Is PWHT required for all thicknesses?

 

[metengr]

The preheat for this material should be 350 deg F minimum, all thicknesses.
PWHT will be based on service conditions regarding maximum hardness requirements.

 

[ZHA]

The hardness requirement is 201 - 237 BHN

 

[ZHA]

What is the PWHT Temperature. I know it should be 50 F below the tempering temperature. But is there any specific requirement?

 

[metengr]

No. You can use heat treatment tempering tables for 4130 to determine the minimum PWHT temperature. For this hardness requirement to be met you must PWHT. The PWHT temperature should be 50 deg F below the original temperature. By the way, what is the hardness of the incoming material??

 

[ZHA]

We haven't received the material yet. But the customer's material specification hardness value say between 201-237 BHN.

 

[MrGezus]

HMN, our bread and butter is 4130 welding. My first question would be whether or not you are required to meet NACE MR0175 250 Vickers requirement. Depending on the part/application we preheat our PQRs at 400-550F. Normally you will stress relieve this at 1175°F for an amount of time that will meet your impacts/hardness requirements. If you'd like to add some additional information I can provide you with some help.

 

[ZHA]

Yes we are required to meet NACE MR0175 requirements. Additionally customer spec says 201-237 BHN.

 

[ZHA]

What is the interpass temperature. 600 F?

 

[metengr]

Your maximum interpass would be 650 deg F.

 

[MrGezus]

Yes we are required to meet NACE MR0175 requirements. Additionally customer spec says 201-237 BHN.

Are you sure this isn't the material requirement and not the welding requirement? As metengr states for the interpass temperature. It may need to be reduced depending on the filler that you use for your toughness properties. If you have issues with the hardness values using a 300-400°F preheat you may want look between increasing your preheat, increasing your time at temperature, or changing your bead profile.

What thickness are your production parts?
What process?
Which position are you taking the PQR?

 

[ZHA]

- 0.344" - 1.88"
- GTAW (ER100S-G), GMAW(ER100S-G), FCAW (E101T1), SAW (F9P8-EF3-F3-H4)
- 5G (All except SAW), SAW (1G)

 

[MrGezus]

- GTAW (ER100S-G), GMAW(ER100S-G), FCAW (E101T1), SAW (F9P8-EF3-F3-H4)

Have you tried using that FCAW wire before? I've had problems in the past using it under prolonged PWHT meeting my mechanical requirements.

Why 5G? I'm not extremely familiar with B31.3 so that might be your reasoning.

 

[ZHA]

To qualify for all positions

 

[ZHA]

MrGezus - DO you use backing gas for ER100S-G tig welding?

 

[A clark]

For performance qualification 5G does not qualify for all positions. 6G or 2G and 5G will qualify for all position welding. Position is a non-essential variable for procedure qualification.

 

[ZHA]

Is PWHT required for all thicknesses for the 4130 material?

 

[metengr]

Thick or thin 4130 base materials, PWHT depends on the hardness requirement for the service conditions.

 

[ZHA]

Thanks for the help Metengr. Can you please let me know where can I find this? Regarding PWHT based on Service conditions?

 

[metengr]

Petrochemical have specific hardness requirements to avoid stress corrosion cracking in service. These requirements are based on temperature and environment for certain materials.