Re: RGS #20

I sat next to the metallurgy guys at work for about 2 years in the late 90s. Their ongoing and constant conversation was about reduction ratios on mill steel. Strand cast steel just simply does NOT provide the same reduction ratios as the old ingot cast, slabbed and rolled mill steel. The tensile and ductile properties that come with highly forged material can't be duplicated, but you can substitute other current metallurgy in many cases to achieve the rated results shown in the ANSI spec. The problem is, when you've got designs or artifacts that relied on the forged properties, you're not going to get the same durability.

High reduction ratios not only change the grain size and carbon structure, but repeatedly reducing tends to 'beat out' micro flaws due to oxygen, phosphorus, and other elements that were in the melt. Those are more difficult to remove in smelted scrap slab than in slab formed from ore of known composition, or highly controlled scrap. (Think: Sandblasting the car before scraping.) Automotive steel, ironically, has to be a high quality because of the stamping operation, but the scrap is thoroughly contaminated by paint and galvanizing.

SRK

Linn W. Moedinger Wrote:
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(snip)
> Interesting comment about boiler steel. When we
> made the second course patch to replace the rock
> damaged shell, I did a weld test, welding a coupon
> of old steel to a coupon of the new steel. When
> the tensile test was done, the sample tore about
> an inch away from the weld in the new steel. You
> can be assured that the old steel has far fewer
> Toyotas and razor blades in it.