In the previous part of this article was covered the first of the steel types, known by the commercial welders. Namely, these were the low-carbon steels and low-alloy steels. The commercial welders perform welding on two other types of steels, these being the medium-carbon steels and the high-carbon steels.

The medium-carbon steels that the stick welders weld at include the AISI series C-1020 to C-1050. With these steels the composition is similar to the low-carbon steels, however the carbon here ranges from 0.25 to 0.50%, while the manganese is in the range between 0.60 to 1.65%.

When the carbon and manganese are of the high level, the low-hydrogen type electrodes are recommended. The multiprocess welder usually prefers these welds when working on thick sections. In such cases sometimes preheating is required and it ranges from 150 to 260 Celsius degrees. Stick welders also require post-heating here, which relieves the stress and harness that is caused by the rapid cooling. The medium-carbon steels are easy to be welded when these precautions are observed.

The high-carbon steels that are known to the arc welders include steels from the AISI series ranging from C-1050 to C-1095. Their composition is similar to the medium-carbon steels, however the carbon ranges from 0.30 to 1.00%. In case a commercial welder performs welding on high-carbon steels, one should take certain precautions. There should be preheating ranging from 300-320oC in case low-hydrogen electrodes are employed. Post-heating treatment is also required. The high-carbon steels can be welded by the multiprocess welders using the same welding processes mentioned before that.

Welding is also performed on low-nickel chrome steels, which belong the group of AISI 3120, 3135, 3140, 3310, and 3316. The carbon here is in the range from 0.14-0.34%, at the same time the manganese ranges from 0.40-0.90%, the nickel ranges from 1.10-3.75%, the silicon ranges from 0.20-0.35%, and the chromium ranges from 0.55-0.75%.

The thin sections on these steels can be welded by the tig welder without preheat if the carbon is low. If the carbon is around 0.20%, the some pre-heating of 100-150oC is required. In case the carbon content is higher, then a preheat of 320oC needs to be used.