welding of nickel chromium steels 1

[metalsmith]

welding of an austenitic type steel with a 309 lsi wire is causing a crack in the fusion zone. pre-heats are around 180c and post heat is around 220c for 8 hours. Welded parts are under vibration and shock stress. I'am told that introducing any other type of filler will cause a martensitic structure and therefore cause cracking.
Is there a Mig Wire better than 309 LSI

 

[Rich2001]

If you give use the chemical compoitions of the base metals I can run some dillution calculations am possible come up with a better alloy to use. Also any environmental information i.e. operating temperature, corrosive conditions, etc.

However, in the meantime, try welding with 316L or 317L , both have slightly less chromium and a fair amount of nickel and Moly.

 

[welding1]

180°C pre heat followed by what appears to be an 8 hour hydrogen release. Surely this can’t be a conventional austenitic stainless steel you are welding? It sounds martensitic to me.

In which case your welding consumable should be OK. Is the cracking occurring during welding or in service. You don’t mention any stress relief which is normal for martensitic material. It may benefit from higher heat input during welding, try stick welding instead of MIG.

Have fun

http://www.gowelding.com

; Technical information in the field of welding

 

[metalsmith]

Chemical Analysis as follows

C SI MN P S CR NI MO V

.35 .55 1.25 .55 .15

.50 .40 .85 .02 .02 1.25 .85 .30

Min & Max

Plate thichness 32mm

I'am told it's an austenitic structure?
No corrosive enviroment and operating temp to 60c

 

[Rich2001]

From the chemical analysis you have a [B}1 ¼% Cr- 1/2% Moly Steel[/b]

Try these welding electrodes:


SMAW 8018-B2

FCAW E 80T1-B2 or B2X

GMAW ER 80S-B2 or B2L

Post Weld Heat Treatment 620-737 C
Hold time for 25mm thickness – 1 hour
Cooling rate to 95 C – 95C/hr/25mm thickness – 95C/hr min

Rich

 

[MURZ]

I agree with Rich, but I would add a preheat temperature of 121 C - 149 C and an interpass temperature not to exceed 235 C. Preheating of CrMo materials is recommended to prevent hardening and cracking when welding.

Also, interruptions of welding in which the weld is allowed to cool to room temperature should be avoided. If welding is interrupted, a “Bake-Out” is suggested. Usually heat the weldment to 315 C for 1-2 hours then allow to cool to room temperature.