rod health

Date 04-28-2004 15:41

According to D1.1 2002 ed. section 5.3.2.2 after you open the can they should be put in a holding oven at 250 degrees immediately and they can only be exposed to the atmosphere 4 hours maximum.

If you want to reuse any rods left out longer than 4 hours max you need to rebake them in an oven between 500 to 800 degrees for rods conforming to AWS A5.1 and 700 to 800 degrees for rods conforming to AWS A5.5.

So according to the specs I would say you should get another box of 7018s just to be on the safe side.

By jwright650 (*****)

Date 04-28-2004 17:19

Texarc,
Search the archives for "low hydrogen" or "wet" and see if you can find the discussion that was here on the forum about the use of rods that had become wet and even changed color. If I remember right Marty even told about some research he did on rods that weren't stored correctly. The whole point in keeping diffused hydrogen out of the weld is to eliminate any possible underbead cracking or other problems such as this. I personally would have thought that welds placed with wet rods would not have passed a visual for porosity (Table 6.1 in D1.1), but anyway, do a search and see what you can find.
John Wright

By texarc

Date 04-28-2004 17:24

Thx I will look my D1.1 is on the way and ill get info from there also.

By jwright650 (*****)

Date 04-29-2004 19:40

http://aws.org/cgi-bin/mwf/topic_show.pl?id=5084#23242

This is the thread I was talking about in the earlier post.
John Wright

By Bill A

Date 04-30-2004 13:32

Let me preface the following remarks by saying I come from the pressure piping / vessel side of things and not the structural side, although I do find that D1.1 is a good general reference for some things.
I read through the thread you linked pretty quickly and found it interesting, but I have to say that I would never judge the acceptability of a potentially deteriorated low hydrogen electrode on the basis of whether porosity was present in the weld, or even on the results of a bend test, unless you only plan to use the electrode for misc. noncritical items in your weekend hobby shop. I usually assume that the primary reason for using a low hy process is to minimize the susceptibility to hydrogen cracking in either the HAZ or in the weld. Depending upon many other factors such as the carbon equivalent of the base metal, the weld cooling rate, the amount of joint restraint, the imposed service stresses, postweld heating, etc., a user can cross that line between crack resistant and crack susceptible with very little change in hydrogen. I have seen data from one type of test indicating that the maximum allowable heat affected zone hardness to reliably avoid cracking in a 0.35 CE steel is reduced from about 370 Vickers to about 350 Vickers when the weld metal hydrogen content is increased from less than 4 ml/100gm to 8 ml/100 gm, both of which are far less hydrogen than the hydogen present in either cellulosic weld metals or in weld metals deposited by improperly stored low hy electrodes. Best practice is to follow manufacturer's guidelines for storage and rebaking. Also a good idea to track the CE of what ever steel is used for procedure testing. With the wide range of allowable compositions in many steel grades, you might have the misfortune of testing a low CE version and then encountering a significantly higher CE version in production. If the test is crack-free and the production welds aren't anf the procedure appears to be followed correctly, then sometimes knowing the CE of test versus prooduction materials can help explain the problem.

By jwright650 (*****)

Date 04-30-2004 15:20

Hi Bill,
I didn't mean to imply that if porosity was or wasn't there that the welds were automatically rejectable, unless they violate the limitations given in Table 6.1. Having said that, I was purely seculating that if wet/damp rods were used, the moisture could quite possibly show up in the form of porosity as the pool is freezing before the steam and gasses can escape.
I do appreciate you explaining all that you did. I keep learning as you and Marty and many others explain more and more about the metallurgical side of the welding.
Keep the good posts coming.
John Wright

By Bill A

Date 04-30-2004 19:39

The point I wanted to clarify is that hydrogen problems can show up as an increased susceptibility to cracking long long before you ever have enough to cause porosity, assuming the microstructure and stress conditions are right.