High-carbon steel (carbon content ranging from 0.50 to 0.90 percent) is used commonly for the manufacture of springs, and are heat treated after fabrication to develop the hard structure necessary to withstand high shear stress and wear. It is manufactured in bar, sheet, and wire forms, and in the annealed or normalized condition in order to be suitable for machining before heat treatment. This steel is difficult to weld because of the hardening effect of heat at the welded joint.
1. Appearance test. The unfinished surface of high-carbon steel is dark gray and similar to other steel. It is more expensive, and is usually worked to produce a smooth surface finish.
2. Fracture test. High-carbon steel usually produces a very fine-grained fracture, whiter than low-carbon steel. Tool steel is harder and more brittle than plate steel or other low-carbon material. High-carbon steel can be hardened by heating to a good red and quenching in water.
3. Spark test. High-carbon steel gives off a large volume of bright yellow-orange sparks.
4. Torch test. Molten high-carbon steel is brighter than lowcarbon steel, and the melting surface has a porous appearance. It sparks more freely than low-carbon (mild) steels, and the sparks are whiter.
The 309L electrode is use commonly for foining mild steel to stainless steels and will work but the filler material strenght will be below your parent material stenght. Recommend with out knowing the alloy to use ER8018.
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