Many have heard this from me, but it bears re-telling.
When I first began forging as a lad, I had built a forge myself after reading some blacksmith books I found in my grandfathers library ( he lived next door). It was a pretty primitive coal forge, but worked. My friends and I would take any piece of metal we found, and pound it into a KSO or SSO. I had a three foot piece of RR track as an anvil, "Alligator" pliers to hold the metal with, and a claw hammer to forge with.
The elderly neighbor across the street came over to see what the burning coal smell was and what we were pounding on. He watched for a while, left, and then came back with two buckets of blacksmith's tools.
He had brought them with him from the farm in South Carolina when he came to Norfolk looking for work during the depression. He gave them to me, and showed me how to use them right. He had a South Carolina (slightly scottisounding) accent. I was a Yankee kid who spent his summers in NH. To say we had a language barrier would be an understatement. He would say, "Git 'er gud n hut, and strick 'er wore ya wan da stil ta move." We worked through it mostly by his showing me and me trying what he did.
After he taught me to forge, the knives looked better, but were junk ,because I was using found metal, re-bar, and some metal I bought from the hardware store. He said, " Ta git gud edjus, ya gots ta hab cobbin. Cobbin 'll mac da stil hahd." I didn't have any idea what cobbin was, so I asked, "Where can I get cobbin?" He said,"Tarns, yehp,tarn is ful O cobbin." I asked where I could get tarns? He said "Da junk yahd." Now, I was totally lost, and he could see it, so he pumped his arm up and down and said, "Ya-no ....fer da jak." Suddenly it dawned....Tire Irons.
That evening, my grandfather told me that it was Carbon in the steel that made it get hard....and he then explained the basic hardening process and metallurgy to me ( he was a physicist).
I went to a scrap yard about 1/4 mile from my house and asked if he had a tire irons he would sell me that I could forge a knife out of. The guy just pointed to an old shack and said, "Tarns?, Yep, thahs a pahl O dem b'hin dat shed, Hep yahself, Tak all ya wan." That I understood...... I ran home, pulled my wagon down to the junk yard, and loaded it full or "Tarns".