Slightly magnetic mystery tubing

[3strucking]

I have a stick of what I thought was 4130 but now I am not sure what it is. It is 1.5 x .083 and it has a ridge kind of like a seam inside. It doesnt look like ERW. It will barely attract a magnet. I will include a picture of a piece that I split open. Any ideas on what it is?

 

[RJSakowski]

Some austenitic stainless steels are weakly magnetic.

 

[pdentrem]

Spark test

 

[Bi11Hudson]

While the size I have worked with is much smaller, it may well be similar tubing. I worked in a steel mill where water was sprayed on the hot steel as it moved down the casting machine. (continuous caster) The instruments I worked with were fitted with 1/4 to 1/2 instrument tubing. As a speculation, the water lines "appeared" to be the same material. Some up to 1-1/2 OD. The tubing was stainless steel, I don't know what grade. But it was mildly magnetic. With the measuring equipment, some was fluids, some gasses. We used water, hydraulic oil, lubrication, and some others. Then there were the gasses, air, nitrogen, natural gas, and a couple more. The mill was dirty, plain and simple. The stainless tubing made an appreciable difference in that dust and dirt. That's my take on it. . .

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[3strucking]

I spark tested it yesterday and the sparks look like the same color as a piece of mild steel tube. My eyes arent what the used to be and I cant see a color difference between the two. Both sparked kind of a orangish red color.

 

[aliva]

316L SS

 

[3strucking]

Thanks for the help.