Casting a windmill gear in grey iron

I'll have to spend more time with this. I thought it was direct reading, but some of the videos reference a chart. I suspect I am missing weights also. All the videos show a larger stack.
The comparison after annealing is my main interest, although I suspect I did it wrong. The piece machined.
For the gear I didn't innoculate, but added carbon increaser to the crucible. It stayed in the mold until about 4oo* when I took the photo, then into ash overnigt and tested cold.

 

Thank you (I think?) for the "tips". I do use certified test coupons to check my Wilson hardness tester (industry standard) as stated above. I think "pushpins" as used in hardness testers are usually referred to as indenters. I also stand by and have substantiated my statements regarding hardness of grey iron and various alloys above. Rc is the most common hardness test I see quoted for metals. A and B are rarely quoted for ferrous metals except in their softest annealed states where better the scale spreads out better in the B scale.

Denis

 

The stack height for the weights on your hardness tester is critical as is using the proper indenter. If the weights are not correct, then the force applied to the indenter is incorrect. So, the resulting reading is meaningless. I would suggest you get the weights right, then use some common materials as verifying (rough sure) test materials. 1018 should come in at ten or under. 4140 prehard should be around 28. A good quality woodworking chisel or hardened parallel for your mill should be around 60 or better. If you can see numbers that look like that, you can conclude you are at least in the ballpark. It would be ideal but maybe impractical to purchase certified coupons for testing. I was lucky and my tester came with several new indenters and with certified coupons.

Cooling to 400F got the iron way below hardening temps, so that was unilikely to cause any problem with hardness. Using FeSi properly really inhibits hardening which can occur especially on "appendages" as small sectional areas can cool quickly in the sand where more massive (like your gear casting) pieces cool slowly enough to not likely harden.

Denis

 

Rockwell testing is most common when tool steel hardness needs to find a fine balance between, hardness, tensile strength, Sheer strength and elastic-ability.

This is why price tags change between 4140, 01, A2, D2, HSS, M1/2.

With cast-iron in high wear situations, I’ve given candy surface coatings using Kasenit with good results.

Dennis, in the end I think we’re beating the same drum?

 

I agree we are writing about the same subject. Our representation of facts concerning the subject of hardness testing diverge some. I have tried to substantiate reasons for my statement where there are differences.

Denis

 

I've looked over my tester and I have test coupons for the B scale, but my indenter is a C scale diamond. The drop wieght is 1kg lead that appears to be home fabricated. I haven't priced indenters or weights. I don't see that weight listed on the specification plate so I may try to track it by serial number.

The Iron Casting Handbook lists some of the numbers Denis mentioned, but the best hardness test seems to be with a 10mm ball indenter and a 3000 kg load. Then the diameter of the indention is measured under a microscope at between 2.5mm and 5mm.