R-Man;
When I was actively employed I could always look up info such as this in books we kept in the shop. Now that I have been retired for some years I simply do not have them at home. I only have an old copy of Machinery's Handbook which has quite limited data.
It gives case hardened 1020 steel drawn to 400°F as having tensile strength of 80K psi & a yield of 50K psi (No case depth given). "Soft" open hearth steel in annealed condition shows 50K & 28K respectively. I do not have figures for the 1020 other than in the case hardened condition, but believe it to fall between these two figures.
1035 steel when through hardened, not cased, oil quenched & then drawn varies in it tensile & yield when drawn from 800°F to 1300°F. At 800° tensile is 96K with yield @ 65K. when drawn to 1300° these figures drop to 83K & 51K. With 1045 under same heat treat conditions tensile varies from 115 K to 95K & yield from 80K to 62K.
I really do not see how the addition of this hard case around the soft core can fail to add some amount to the strength, even though not necessarily a large part.
