Welding 1144 Stressproof 1

[Mandrake22]

I know all the books say not to weld stressproof, but if you were on a ship that was sinking in the middle of the North Atlantic in winter and you could save everyone by welding a Ø2.5" stressproof shaft to a 4" wide x 2 1/2" thick A36 crank arm how would it best be done?

 

[leche]

i currently weld 1144 to mild steel using flux core wire. the results are satisfactory, but i also an interested in possibly better ways to weld this.

 

[TVP]

1144 qualifies as a medium-carbon steel, which can be welded successfully by arc welding provided suitable precautions are taken. Hardenability is a concern--formation of martensite is quite likely in the weld, so preheating and postheating treatments are necessary. Low-hydrogen consumables and procedures are a must in order to reduce the likelihood of hydrogen-induced cracking. If the stress levels in the weld/HAZ are such that the original properties of the 1144 stressproof are required, a post-weld heat treatment may be needed.

The most significant reason that 11xx series steels are deemed not suitable for arc welding is because they contain large amounts (in the case of 1144 I would say enormous) of sulfur and phosphorus (machinability aids), which are extremely detrimental to weld quality. Solidification cracking, porosity formation, and lamellar tearing are all defects that are frequently encountered.

At your diameter/thickness, the minimum preheat and interpass temperature should be around 177-230 C (350-450 F). 0.45 % carbon is listed as the cut-off (ASM HANDBOOK Volume 5)-- below this use 177 C as the min, above 0.45% use 230 C. Post-weld heat treatment is recommended-- temperature range should be 590-675 C (1100-1250 F). Peening is recommended.

As I mentioned before, a low-hydrogen consumable is necessary with a basic slag sytem-- low hydrogen reduces porosity due to hydrogen sulfide formation and basic slag reduces the S & P levels of the weld metal. Shielded metal arc welding electrodes such as E7015, E7016, and E7018 are preferred. For gas-shielded flux-cored electrodes, E70T-5 and E71T-5 types are preferred over T-1 electrodes. Self-shielded flux-cored electrodes of the T-4, T-7, and T-8 types are recommended. Low currents should be used with all electrodes.

I highly recommend obtaining ASM HANDBOOK Volume 5 Welding, Brazing, and Soldering. It is an excellent reference for all welding processes. You can obtain this book from ASM International at

http://www.asminternational.org

. If you are open to processes other than arc welding, friction welding is a better option-- no melting is involved, so you basically eliminate all of the defects mentioned above, except possibly the martensite formation.

 

[Mandrake22]

TVP,

I won't have to worry about that ship sinking, you have blown me out of the water with your response! Thanks.

 

[butelja]

Step 1: Secure the lifeboats.

Step 2: Cross fingers, chant appropriate incantations for good luck.

Step 3: Proceed as recommended by TVP