Grinding Pre heat treated steel will ruin the HT?

B

blzwow

Joined
Nov 26, 2016
Messages
53
First of all,There is no professional commercial heat treating companies for Powder metal in my country.So If our knifemaker want to make Powder metal knives,they have to buy PM blanks and give it to Peters or BOS for heat treatment,then ship them back and Cutting, profiling, drilling, grinding,That's the only way.
Here is the question: If you are careful not to cause overheating in the process Will Grinding the heat treated steel ruin the HT(For both carbon steel and powder steel)?
 
Last edited:
Grinding afternheat treat will only ruin the heat treat if the temperature of the blade exceeds the tempering temperature. It is easy over heat thin sections when grinding especially with the finer grit belts. That being said, grinding ingroduces stress in the steel. If I were post heat treat grinding, I would run a two hour temperature cycle at 50°F (27°C) less than the temper temperature for the steel you are using. This shouldn't decrease the hardness a noticable amount and will reduce the stress greatly.
 
AS long as you're careful not to over heat blade while grinding, no problem. If the color ever hits blue - you've overheated and lost the temper. The idea is to grind one pass, dip in water, grind other side for one pass, dip in water again. As long as you can hold the blade in your bare hand you should be good. Many of us grind post HT.
 
Ken H> said:
AS long as you're careful not to over heat blade while grinding, no problem. If the color ever hits blue - you've overheated and lost the temper. The idea is to grind one pass, dip in water, grind other side for one pass, dip in water again. As long as you can hold the blade in your bare hand you should be good. Many of us grind post HT.
Click to expand...
Thanks ! Sorry for my english,''grind post HT''means grind metal first and then go for HT?
 
before heat treat= Pre-heat treat
after heat treat = post heat treat
So grinding post heat treat means grinding after heat treat
Grinding pre heat treat means grinding before heat treat
 
Ken H> said:
AS long as you're careful not to over heat blade while grinding, no problem. If the color ever hits blue - you've overheated and lost the temper. The idea is to grind one pass, dip in water, grind other side for one pass, dip in water again. As long as you can hold the blade in your bare hand you should be good. Many of us grind post HT.
Click to expand...
I grind AFTER Heat Treat by PAUL Bos for all of my stainless steels, 440C, AEL-B, CPM Steels and I dip and pass, dip & Pass, this is what I invented my Rhino Finger Skins for and it works great. I grind, finish and I’m done with the steel work except for the final edge..
 
It sounds like you are talking about having the steels heat treated as flat bars with no shape. If that’s the case, it’s still possible to grind after hardening but will be more difficult and eat up more belts. Many of us bevel after hardening but very few harden before profiling or drilling holes. I wouldn’t be able to deal with how slow it would be trying to keep a billet cool while profiling. I believe that would be extremely time consuming. You will also need carbide bits to reliably drill holes in hardened steels. As long as the grinding doesn’t heat the steel up hotter than the temperature used for tempering, you won’t have an issue, but with profiling that may be difficult.
 
blzwow said:
First of all,There is no professional commercial heat treating companies for Powder metal in my country.So If our knifemaker want to make Powder metal knives,they have to buy PM blanks and give it to Peters or BOS for heat treatment,then ship them back and Cutting, profiling, drilling, grinding,That's the only way.
Here is the question: If you are careful not to cause overheating in the process Will Grinding the heat treated steel ruin the HT(For both carbon steel and powder steel)?
Click to expand...
There was your answer :) Only you need good ceramic belt and decent speed.......
 
Have you tried talking to any machine shops? I'm not sure about in China, but over here its not that uncommon for one to have a heat treating oven.

That said, I do all of my bevel grinding apart from really big Bowie's after heat treating. I personally find the ceramic belts I use to work better on hardened steel than they do on annealed.
 
As mentioned before, for sure you should profile the blade with all holes drilled BEFORE heat treat. It is just fine to grind bevels after heat treat, but must prevent heat from causing a color change during grinding.
 
I would like to have option to buy flat bars from already hardened steel ........steel like S90V for example .
 
Last edited:
Powder steel stock is heat treated just like any other stainless steel. If a company can do 440C, it can do CPM-154.

Grinding after heat treatment is a good method, but you have to either use a wet grinder, or be very careful not to overheat the edge. Using a variable speed grinder is almost a necessity. Dunk the blade in a bucket of water after every pass or two. Make quick passes and use fresh belts.

Hope this helps - haoyun
 
Most Chinese knife makers start with heat treated steel. They do all the drilling, cutting, profiling, grinding, and machining from the pre-heat treated state.

Seems like there are several advantages to this method. Do all grinding with sharp belts and there shouldn’t be any problems.

Hoss
 
DevinT said:
Most Chinese knife makers start with heat treated steel. They do all the drilling, cutting, profiling, grinding, and machining from the pre-heat treated state.

Seems like there are several advantages to this method. Do all grinding with sharp belts and there shouldn’t be any problems.

Hoss
Click to expand...

Yes ! It is much faster and more clean process . Cut , shape , drill , grind and put scale on . Done :) No wrapped or bend blade , no worry about Ht and temper , no oil , no HT oven ......That way even I can make solid knife . Only I need is ..... pay to play :)That s way I wish that someone will start to sell hardened steel :(
Here are two blank I did that way , HSS steel :)
AcFoOIT.jpg
 
Thanks to all of you guys! It seems there will be no problem as long as it does not exceed the tempering temperature.I found this on the alphaknifesupply web. It looks like 3V needs a high temperature to temperingthe.
QQ20180118085016_zpstyyabohv.jpg
 
You must log in or register to reply here.
Back
Top