Q: Is it possible to weld AISI 4130 to ASTM A514 (commonly called T1) material? If so, what would be the appropriate stick electrode? I have always tried to match the steel strength when selecting the filler metal but I am not sure how to approach this application.

A: Yes, it is possible to weld AISI 4130 to ASTM A514. The real question is what you need for strength in the weldment. Loading conditions should dictate the filler metal strength selection not the materials you are welding particularly when dealing with the AISI materials like 4130. The filler metal selected will have to be low hydrogen as both materials are susceptible to hydrogen cracking.

A material such as AISI 4130 can have a wide range of mechanical properties that will be based on the heat treatment condition of the material. It will have a range in ultimate strength of 120 ksi to more than 225 ksi, and yield strength of 95 ksi to nearly 200 ksi.

ASTM A514, depending on the grade that is being used, can have an ultimate strength of 110 ksi to 130ksi, and minimum yield strength of 100ksi.

Stick electrodes such as E7018 may be acceptable given appropriate loading conditions.

However, matching the lower strength of the two materials, depending on loading conditions and joint configuration also could generate an acceptable solution. In this case, it is most likely that the A514 material is the lower-strength material, and stick electrodes such as E11018 or E12018 would be acceptable to match the A514.

Remember that the filler metal should be purchased in a hermetically sealed container and properly stored after opening to minimize the pickup of hydrogen.

The AISI 4130 material has significant hardenability (depth of maximum hardening) and can reach a high hardness as well due to the carbon content.

A preheat and minimum interpass temperature of 450 degrees to 500 degrees F should be used to reduce the chances of hydrogen-assisted cracking.

Keep in mind that the maximum preheat for A514 is 400 degrees F and, depending on the thickness of the A514, heat input must be controlled to avoid over-tempering the heat affected zone. That would produce an undesirable loss of ductility and strength.

To balance the needs of both steels, a maximum preheat of 400 degrees F should be used.

Welding maximum heat input then will be determined by the thickness of A514 material. For example: Maximum heat input of 40 KJ/in. can be used to weld in. thick A514 for T1 and T1 Type C steels, and only 18 KJ/in. for Type A and B.

A good resource and maximum heat input chart can be found at the following website: www.mittalsteel.com/documents/en/Inlandflats/Applications/HOW%20TO%20WELD.pdf

Good low hydrogen practice must be maintained when joining these steels which includes but is not limited to:

• Proper material preparation that includes removing mill scale, dirt, rust, grease or other hydrocarbon producing materials.
• Proper filler metal control that includes the use known materials that are from a new, hermetically sealed container or storage properly in a rod oven in accordance with manufacturers recommendations.

Additionally, the materials shall be stored to minimize hydrogen pickup once opened. You should reference manufacturers’ recommendations for proper storage.

Finally, because of the reduced pre-heat and interpass temperature, you may consider using a temper bead technique on the side of the joint with the AISI 4130 material.

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.