Q: Do you have any information the weldability of ASTM A148- 65 (80-50). This material was used in castings for bridge bearings for a bridge constructed in 1967. Our desire is to weld ASTM A572 Grade 50 plates to the ASTM A148-65 (80-50).

A: I checked the ASTM A148 80-50 specification you referenced in your request and found minimal compositional information. The only reference to composition is that the sulfur must be 0.06 percent Max and phosphorus 0.05 percent Max.

There was no reference to ASTM A148-65 within the specification, which was written around steel castings that are subjected to higher mechanical stresses than those covered in ASTM A27. The ASTM A27 specification contains a reference to a grade 65-35 material that essentially is equivalent to a SAE 1030 alloy heat treated to a minimum of 65ksi tensile strength and 35ksi yield strength.

Without clarity as to which specification is applicable, it is difficult to determine actual weldability. However, it could be assumed that this material is essentially a carbon-manganese-silicon steel that is similar to an SAE 1040 and is generally weldable. Good low hydrogen practice shall be mandatory along with a preheat in the range of 350 degree to 500 degree F depending on restraint, followed by a slow cool down.

A refined recommendation may be generated by taking a sample of the steel and having it analyzed for carbon, silicon and manganese, sulfur and phosphorus.

Q: Please let me know whether you have a classified weld metal analysis of an ER70S-6 using a gas mix of 80 percent Argon – 20 percent CO2 for spray transfer in accordance with ASME Section 9. This is for filling my Welding Procedure Specification essential variables QW-442 A-numbers, classification of ferrous weld metal analysis for procedure qualification.

A: Wires manufactured in accordance with AWS A5.18 to the ER70S-6 specification generally will fall within the ASME Section IX, Table QW-442 A-1 deposit composition specification regardless of shielding gas.

Keep in mind that the AWS A5.18 specification is for the wire chemical composition and the ASME Section IX classification for A-number is for deposit composition.

As you are most likely aware, the deposit composition can exceed the A-1 compositional specification in Table QW-442 in ASME Section IX for both Manganese and Silicon and still be within the AWS A5.18 ER70S-6 composition specification. Table QW-442 in ASME Section IX lists A-1 deposit composition classification limits the Manganese to a maximum of 1.60 percent and the Silicon to 1.00 percent . Within the AWS A5.18 ER70S-6 specification the wire composition for Manganese can range from 1.40 percent to 1.80 percent and the Silicon 0.80 percent to 1.00 percent.

Wires tested in accordance with AWS A5.18 use 100 percent CO2 shielding gas for qualification, and the standard gives no provision for testing with other shielding gases. Using shielding gases higher in CO2 will reduce these alloy levels transferred from the wire to the deposit with 100 percent CO2 being the worst case condition. Typically, in an all weld metal sample using a gas mix like 80 percent Argon – 20 percent CO2 you will see the Manganese and Silicon levels be reduced approximately 0.20 percent each from the nominal wire composition which tends to keep wires with compositions at the top of the AWS A5.18 alloy specifications within the deposit compositional requirements of A-1 in table QW 442 of ASME Section IX.

There are additional provisions within ASME Section IX for documenting the A-number per QW- 404.5 for the GMAW process.

This column is sponsored by Penton and the Lincoln Electric Co., Cleveland. Dave Barton is a senior welding engineer in the Application Engineering Group of The Lincoln Electric Co. He oversees welding procedure development for both new technology and existing products, performs failure analyses for customers, and serves as a consultant on welding application problems. Barton has been with Lincoln Electric for 21 years. Send your questions for Mr. Barton in care of WDF by e-mail to: askdav@penton.com.