Annealing parts
#1
Annealing parts
I run an annealing oven at work, as well as two smaller curing ovens, and I've been curious if tossing some engine parts, crank, rods, etc. in during a burn would do me any good or be a waist of time. I commonly do 1150* stress relive burns as well as 1550 "full anneal" burns. The idea is reduce hardness and increase ductility, making it more likely to flex then crack or break? Thoughts?
Last edited by young olds; March 1st, 2017 at 04:50 PM.
#2
I'm not sure what the hardness is on a stock crank nor the material used, however I have been having much better luck with "Form Blocks" being heat treated to 54-56 for both A2-D2 material. Less cracking and breakage.
The days of heat treating to 58-60 and 60-62 are gone. Depending on the hardness of a stock crank, I would think you could draw it back to 54 if not more if breakage and cracking is an issue. It certainly wouldn't flex at 54rc
I'm sure your seeing tool steels coming out with less hardness in the past few years as well since your in the business.
The days of heat treating to 58-60 and 60-62 are gone. Depending on the hardness of a stock crank, I would think you could draw it back to 54 if not more if breakage and cracking is an issue. It certainly wouldn't flex at 54rc
I'm sure your seeing tool steels coming out with less hardness in the past few years as well since your in the business.
#3
There are two different issues here. One is stress relieving, where you heat and slowly cool the part to release residual stresses. This is useful on complex castings like engine blocks, but frankly, a used block is already stress relieved from numerous heat-cool cycles over it's lifetime.
The second is annealing, which as you point out reduces hardening and improves ductility. This is usually used for complex weldments where thermal stresses can be induced during welding.
The thing you DON'T want to do is to anneal a heat treated part. Yes, it will improve ductility, but at the loss of yield and ultimate strength. This is like the people who think it's better to use a Grade 5 bolt instead of a Grade 8 bolt because the Grade 8 is more "brittle". While that is true, it ignores the fact that the Grade 5 bolt will have totally failed before the Grade 8 bolt even starts to yield. In that case, a poor choice.
The second is annealing, which as you point out reduces hardening and improves ductility. This is usually used for complex weldments where thermal stresses can be induced during welding.
The thing you DON'T want to do is to anneal a heat treated part. Yes, it will improve ductility, but at the loss of yield and ultimate strength. This is like the people who think it's better to use a Grade 5 bolt instead of a Grade 8 bolt because the Grade 8 is more "brittle". While that is true, it ignores the fact that the Grade 5 bolt will have totally failed before the Grade 8 bolt even starts to yield. In that case, a poor choice.
#5
As for a crank, you could check the hardness prior to drawing in back, I'm sure you know when you anneal something it throws it out of tolerance so regrinding is a must.
I would be interested in knowing what the hardness of a factory crank would be if someone here has the numbers.
#7
#8
This is off topic a little, but... Has anyone ever coated bearing surfaces, or any other internal engine parts for wear longevity.
Just because, we have been coating die sections for several years now, especially on high volume stampings.
Even something like inexpensive Tialn coating used on carbide endmills... say on valves, rings, bearings, pistons. ?
Anyone doing this ?
Thanks
Eric
Just because, we have been coating die sections for several years now, especially on high volume stampings.
Even something like inexpensive Tialn coating used on carbide endmills... say on valves, rings, bearings, pistons. ?
Anyone doing this ?
Thanks
Eric
#9
There are friction reducing coatings as well as thermal coatings already in use on engines they just aren't main stream for the everyday builder. What do you guys think about welding a block with invar? It's a nickel-iron allow with a low thermal expansion/contraction coefficient, and we do a lot of invar tooling where I work. Always wanted to try building up a big block for 4 bolt caps
#10
I run an annealing oven at work, as well as two smaller curing ovens, and I've been curious if tossing some engine parts, crank, rods, etc. in during a burn would do me any good or be a waist of time. I commonly do 1150* stress relive burns as well as 1550 "full anneal" burns. The idea is reduce hardness and increase ductility, making it more likely to flex then crack or break? Thoughts?
This is off topic a little, but... Has anyone ever coated bearing surfaces, or any other internal engine parts for wear longevity.
Just because, we have been coating die sections for several years now, especially on high volume stampings.
Even something like inexpensive Tialn coating used on carbide endmills... say on valves, rings, bearings, pistons. ?
Anyone doing this ?
Thanks
Eric
Just because, we have been coating die sections for several years now, especially on high volume stampings.
Even something like inexpensive Tialn coating used on carbide endmills... say on valves, rings, bearings, pistons. ?
Anyone doing this ?
Thanks
Eric
Ray