3 Reasons To Not Weld Free Machining Steels

August 25, 2009

Any type of arc welding of resulfurized steels is generally avoided. This post will give you some  reasons why. Resulfurized steels are free machining steels. This includes steel grades in the 11XX and 12XX series,  such as 1215, 12L14,  1117, 1137, and 1144. These steels contain sulfur and may contain lead. These two elements will create low melting temperature constituents that will cause cracks.

Here are 3 reasons not to weld resulfurized free machining steels:

  1. Sulfur reduces weldability.  The higher levels of sulfur make a slaggy joint.
  2. The high volume fraction of manganese sulfides also hold hydrogen. This hydrogen can then create post weld cracking.
  3. Both sulfur and lead  can become a fume inhalation hazard at welding temperature.

Finally, with the exception of grade 1144, resulfurized steels are generally not sold to mechanical property requirements. Welding implies mechanical property performance.

We have seen 1215 welded using an inertial or friction welding process. But these welds are  usually not subject to mechanical loads, merely attachment. Here’s a video of a friction weld process for truck axles from Thompson Friction Welding in the UK.

Want a second opinion? Dave Barton at Lincoln Electric hosts a column   Barton’s Q&A in Welding Magazine published by Penton.  The second question in this column deals with welding 12L14.

Think of weldability and machinability as two sides of the material coin.

Heads it machines well, welds lousy, Tails...

Heads it machines well, welds lousy, Tails...

You can usually win on one, but at the expense of the other. If you need to weld, a low carbon plain carbon steel is your best bet.


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