4130 Stress Relieving

Date 03-14-2005 01:20

I have a welded 4130 vs 4130 test pipe coupon 5.5" O.D. x 0.875" thick. I run PWHT at 600*C for 2 hours and 15 min. is this good or bad? What will be the effect of this condition to my test coupon? Do you think the microstructure of my metal is affected? I sloowly cooled the weldment to room temperature. I am about to perform a mechanical test but I want to have a clear idea of what will happen to my specimen before subjecting it to mechanical test. Thanks in advance

By Mikeomni1 (*)

Date 03-14-2005 15:22

Was the base metal quenched and tempered prior to welding and if so, what was the tempering temperture?

Regards,
Mike

By peterbil (*)

Date 03-17-2005 04:03

Hi Mike,

The base metal was bought on a normalized and quenched condition the application of this pipe will be for geothermal wellhead. I have a preheat temperature of 340*F-400*F, cooling rate was at 200*F till room temperature.

By Mikeomni1 (*)

Date 03-17-2005 16:48

Peter, I find it strange that the material was not tempered after quenching prior to welding. But if the base material is in the as-quenched condition (extremely hard and extremely high tensile strength), the PWHT you stated above will temper (draw down) the hardness and tenisle strength. I know of no way to predict how much without knowing the properties prior to PWHT. Only testing will tell you.

Regards,
Mike

By - Date 03-19-2005 01:01

A 0.875" thickness coupon should have a minimun preheat and interpass temperature of 400 F.. For the thickness you listed, the 600 C. PWHT is right in line. But, the preheat temperature is very important in this case. Immediately after welding, the piece should be cooled to a temperature below the preheat temperature to a lower temperature where the transformation of austenite to martensite is completed. Then the piece should be immediately heated to the stress-relieving temperature where the martensite in the welded joint will become tempered and softened. After holding it at temperature for the specified time, the piece can be cooled to room temperature without the danger of cracking. You failed to mention exactly what filler metal you used. Corresponding fillers specifically for welding 4130 is listed in ASM specification 6457A.

CM

By peterbil (*)

Date 04-02-2005 04:12

Hi Mike and CM,
Sorry I forgot to mention that my base metal was bought on a quenched and tempered condition I don't have the tempering temperature with me. A combination of GTAW and SMAW process were used utilizing filler rod ER80S-B2 and electrode E8018-B2 respectively.