Base Metal Grouping

[JustinShelley]

I am working on a job where the material type is unknown, so material samples were taken from the member and sent to an engineer for testing. He has given a report of the chemical composition, which I have listed below, and he has grouped the material as an AWS D1.1 Group II.

What properties determine which base metal grouping this material would be? I have compared his results to an MTR of an AWS Group I material, and they are very similar. I have tried to contact the engineer who pefromed the testing and cannot get an answer from him. I need to find a material type for PQR testing, and a Group II material in pipe form is limited to just a few types.

Equotip Field Hardness 393 / 375
Rockwell Hardness 69
Tensile Strength 60 KSI
C .20
MN 1.13
SI .21
P .012
S .020
CR .07
V .03
MO .02
NI .06
CU .14
CE .43

 

[Metalhead97]

LinkLink

Those should help

MH

http://www.linkedin.com/pub/luke-autry/1b/510/566

 

[JustinShelley]

I've looked through all the AWS and ASME tables for material specifications for steels in pipe forms that this testing could verify. The tensile strength of the tested sample is well below any minimum tensile strength listed for any Group II material.

My real question is how are base metals grouped? Is it by tensile strength ( which varies wildly from material to material depending on product form), chemical composition, carbon equivalent, etc...??

I cannot use any prequalified joints for procedure because the OEM uses 80 and 90 series wire to weld these members together which is an essential variable if you go up in filler metal strength. We are wanting to follow the processes the OEM uses in our repair.

The report I have on the material tested is similar to A106 Grade B more than any other pipe material I have looked at, but that is listed as a Group I metal.

 

[metengr]

ASME B&PV Code, as well as AWS, assigns P-No and group base materials for welding based on the following metallurgical characteristics;
Chemical composition range (influences CE and ultimately preheat and PWHT requirements)
Mechanical properties
Notch toughness

The approach above is to avoid having numerous repeated welding procedure specifications/qualifications related to each base material. Materials characterized by chemical composition and mechanical property ranges can be classified because they have been shown by qualification over the years to respond similarly during and after welding.

Unknown or unlisted materials require extra caution by users when determining an approximate P-No and group should be assigned. It is best to leave unknown materials as unassigned and qualify them separately.