FILLER METALS FOR WELDING ASTM A-333 1

[alejo2003]

I'm working on the WPS for welding a 10" pipe ASTM A-333 GR 6.
I have a question: What is the best option for selection the filler metal? I think first on AWS E 7018-1 H4R for the root and the fill and presentation layers.
But i discover that the deparment of agriculture of the state of minnesota in USA actually use E-6010 on the root pass and E-7018 for the fill and presention layer.
What is the best option and why?
What said the AWS D1.1 About it?

 

[Rich2001]

Grade 6 is a low alloy steel similar to 4032 in properties. Tensile strength requirement for Grade 6 is 60 ksi minimum and notched-bar impact strength is 4 to 13 ft. lbs. depending upon section size.

In many cases one tries to overmatch the mechanial properties of the basemetal so using a E70xx electrode with a minimum tensile strength of 70 ksi is typical. Another advantage of the E70XX electrode is they are low-hydrogen while the E6010 is not. The clean up odf the E7018 is much easier than cleaning the E6010 prior to putting in the next pass. Though with the E6010 the root pass is easier to put in. In addition the E6010 might improve the notch toughness, though one has to look at the actual base metal chemistry. Another advantage of the E6010 is the lower Silicon content, this maybe important if you are planning on heat-treating the welded assembly, since the migration of silicon during thermal processing can sweep alloy elements away from areas where they are needed.

In a lot of chemical plant pipe welding project that I have been involved in E6010 is routinely used for the root pass.

 

[alejo2003]

thanks for the answer, but i have a doubt: How response the E 6010 working at lower temperatures (-30 deg C)

 

[Rich2001]

AWS Specification Charpy V-Notch Impacts for E6010
Charpy V-Notch Impacts
@ -29C (Joules) 27.0

AWS Specification Charpy V-Notch Impacts for E7018
Charpy V-Notch Impacts
@ -29C (Joules) 27.0

If actual values depend on the specific alloying elements in the filler and base metal and the heat input/processing of the weld. (minute changes have a significant effect) You need to take a good look at the base metal chemistry (be sure to obtain the mill certs). (One has to take the charpy values with a grain of salt... If you machine 2 samples, 1 to the minimum dimension and the other to maximum dimensions and run the impact tests you can obtain an order of magnatude difference in values. The ASTM procdure need to be improved!)

 

[alejo2003]

The actual values of charpy v- notch impact requirement for the electrodes are:

E-6010 : 27 Joules @ -29 deg C
E-7018 : 27 Joules @ -29 deg C
but the
E-7018-1 : 27 Jolues @ -46 deg C

The work temperature for the pipe is -30 deg C

What do you think now?

 

[Rich2001]

If you need impact, why not use E8018-N, the addition of the Nickel cause some austentic to form, increasing the notch toughness, rather than the E7018-1. However, note that at the electrode manufacturer's testing facility they dimensions of the v notch are adjusted within the ASTM prescribed procdure to obtain the highest value, so really comparing one set of values to another is somewhat useless, because the notches may be up to 2 mm difference in size.

Watch the metallurgy of your base material, if you need toughness. Keep your rod dry, besure to use a portable rod oven at the site.

>What said the AWS D1.1 About it

ASTM A333 Gr.6 is not listed in the Prequalified Base Metal/Filler Metal Combination Table (Table 3.1).