Skip to main content

[MW:24815] HAZ cracking of 800HT forgingings

By Materials & Welding
We have been experiencing susceptibility to heat affected zone cracking in 800HT (UNS N08811) forgings.  This has not been a problem with all heats but rather appears to be a random type problem.  The problem to date has been limited to solely to forged material.  All forgings are supplied to ASME SB-366 with required solution anneal (2100F~2180F} followed by rapid air or water quench.  A limited metallurgical examination suggested that the cause was liquation cracking.  Welding was performed by GTAW with ERNiCr-3, no preheat, maximum interpass 300F.

When issue arises, we have used a buttering type technique;  welding a layer of ERNiCr-3 on the faying surface with lowest achievable heat input and no  preheat and minimal interpass prior to making the actual weld.  This alleviates the problem about 33% of the time. 

Questions are as follows:
1)  have others observed cracking problems when welding  forgings made from 800HT type material?
2)  what material controls (chemistry limitations, heat treat requirements, etc) were put in place to mitigate cracking susceptibility?  have they been successful?
3)  other special welding controls?

I have found only a couple of papers dealing with this issue.  Most recent was an article in the AWS Journal by Dupont, however this study was on autogenous welding on tubing.  Other than that there was some earlier work done at Oak Ridge which showed some heats of alloy 800 susceptible to cracking but with no real conclusions on how to mitigate.

Any comments or discussion would be appreciated.  Any additional papers/references dealing with this topic would also be appreciated.

--
http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&trk=anet_ug_hm
The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
---
You received this message because you are subscribed to the Google Groups "Materials & Welding" group.
To unsubscribe from this group and stop receiving emails from it, send an email to materials-welding+unsubscribe@googlegroups.com.
To post to this group, send email to materials-welding@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/materials-welding/6de678c7-b17b-4281-ab16-9d08400bbc98%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.

Comments

Post a Comment

Popular posts from this blog

Re: [MW:34105] SA266 GR4N 4 Cycle SPWHT

By Materials & Welding
Hi,  You are correct, Minimum refers to the one cycle for which this part will expose until final work shop PWHT. hence mill test certificate shall include this.  Max. SPWHT, refers to additional cycles of heat treatment that are reserved for future repairs during equipment lifetime.  Again, these simulated no. Of cycles shall be specified in MTC.  The idea is we need to make sure that steel mechanical properties are not compromised upon exposure to multiple repairs (i e 4 cycles in your case).  One could say, if steel is subjected to 4 cycles and is ok, then it should by defacto be good for one cycle, yet, this is wrong assumption cause mechanical problems and microstructure of materials varies accordingly based on no. Of cycles for which material will expose. This is apparent in alloy steel and especially for impact test values as an example.  In your case, this forged CS with properties before PWHT can be understood to be " as forged" condition (i.e. Wit...
Post a Comment
Read more

Materails FAQs

By Materials & Welding
Q: What are equivalents for standard Q 235 B (and Q 235 A) for U-channels? (asked by: boris.vielhaber@vait.com) A: DIN Nr. = 2393 T.2, 2394 T.2, EN 10025 W. Nr. DIN 17007 = 1.0038 Design DIN 17006 = RSt 37-2, S235JRG2 (Fe 360 B) Q: What is St DIN 2391 BK material? (asked by: dmcandrews@automaticstamp.com) A: Precision steel tubes, cold-finished/hard. Q: What is C.D.W. Boiler Tube? (asked by: montydude123@yahoo.com) A: Cold Drawn Welded Boiler Tube. Q: WHAT IS W.Nr. 1.4301? PLS TELL US IN EASY LANGUAGUE (asked...
21 comments
Read more

Heat tint (temper) colours on stainless steel surfaces heated in air // Heat tint

By Materials & Welding
Introduction The colour formed when stainless steel is heated, either in a furnace application or in the heat affected zone of welds, is dependent on several factors that are related to the oxidation resistance of the steel. The heat tint or temper colour formed is caused by the progressive thickening of the surface oxide layer and so, as temperature is increased, the colours change.   Oxidation resistance of stainless steels However, there are several factors that affect the degree of colour change and so there is no a single table of colour and temperature that represents all cases. The colours formed can only be used as an indication of the temperature to which the steel has been heated. Factors affecting the heat tint colours formed Steel composition The chromium content is the most important single factor affecting oxidation resistance. The higher the chromium, the more heat resistant the steel and so the development of the heat tint colou...
Post a Comment
Read more