Cr-Mo Weld & HAZ Property Data
Cr-Mo Weld & HAZ Property Data
(OP)
I have just run into yet another case of extremely high hardness in Cr-Mo weld and HAZ. Since I never had the joy of working with these much in a production environment, I don't know that much about the as-welded mechanical properties, especially when things have gone wrong.
So I am seeking any and all data on as-welded hardness for 1¼Cr-½Mo up to 12%Cr alloys and everything in between (conventional alloys, not the newer CSEFs). Process, preheat as well as base metal thickness are pertinent to the data. CCT diagrams would be very useful.
Thanks in advance!
So I am seeking any and all data on as-welded hardness for 1¼Cr-½Mo up to 12%Cr alloys and everything in between (conventional alloys, not the newer CSEFs). Process, preheat as well as base metal thickness are pertinent to the data. CCT diagrams would be very useful.
Thanks in advance!





RE: Cr-Mo Weld & HAZ Property Data
brimstoner;
Find someone that has EPRI technical reports for you to review. Some of the B&W Intermediate Croloy boiler tube reference brochures had excellent information on these alloys - hardness and weldability.
Try to search the internet for EPRI temper bead welding documents released to the public or other similar publications because there you might find as-welded and typical PWHT hardness values for P-No 4 and
P-No 5A base materials.
RE: Cr-Mo Weld & HAZ Property Data
What condition are you welding the alloy steel in? Sounds like the precipitation hardening kinetics are fast. If the kinetics are anything like some high Al/Ti Ni superalloys you may need to try over-aging prior to welding. The worst thing you can do is weld in the solutioned condition. The fast precipitation hardening alloys are always a pain.
Metalhead
RE: Cr-Mo Weld & HAZ Property Data
These alloys can be welded with or without PWHT - it depends on thickness. They respond very well to tempering from PWHT.
RE: Cr-Mo Weld & HAZ Property Data
RE: Cr-Mo Weld & HAZ Property Data
RE: Cr-Mo Weld & HAZ Property Data
I could find almost no info on the Croloy alloys on the www.
But I do have a number of temper bead reports and they are useful in demarcating the line of optimum preheat/no PWHT. Any hardness higher than this indicates less than optimum preheat/no PWHT. So a good suggestion.
Ultimately I wish to be able to comment intelligently on the extreme hardness numbers I am seeing - 400-450 HV in the weld and HAZ of Grade 9 piping. Composition checks out OK in weld and base.
There is no substitute for procedure development and PQR data though.
RE: Cr-Mo Weld & HAZ Property Data
metalhead
RE: Cr-Mo Weld & HAZ Property Data
My reference materials indicate typical base metal hardness of Grade 9 should be about 87 - 88 HRB (175 HV). Sounds like you need to look at preheat and PWHT parameters to bring down the HAZ and weld hardness.
Aaron Tanzer
www.lehightesting.com
RE: Cr-Mo Weld & HAZ Property Data
I understand the metallurgy and how to weld these alloys, I only lack data points at the extremes of 'doing it wrong'.
RE: Cr-Mo Weld & HAZ Property Data
The P9 alloy weld would have to have received PWHT. The >400 BHN is not atypical in the as-welded state. The weld was obviously not subject to the Code(s) mandated PWHT requirements.
RE: Cr-Mo Weld & HAZ Property Data
Think I'll stop my favorite rant right here before it gets started!!
RE: Cr-Mo Weld & HAZ Property Data