Call for Charpy toughness samples

Well, still no grandson, but my son did birth the kidney stone, so there's some progress!!

I got to work on some of Warren's coupons today, and have a heads up for those who are grinding. I used a 3/8 carbide roughing end mill to bring the 10mm dimension closer to finish size so as to not have too much stock to remove. Ran it at 500 rpm, dry, with a pretty aggressive feed taking .010 passes. It ate the hardened steel, with virtually no heat transferred to the coupon. Way faster than grinding! Leaving .003-.005 per side to grind.

Warren! Get better, man!

Hoss, kind thoughts coming your way regarding your health issues. I continue to be educated by the Thomas men and many others here. Thank you so much for that!
 
Keith Nix said:
Well, still no grandson, but my son did birth the kidney stone, so there's some progress!!

I got to work on some of Warren's coupons today, and have a heads up for those who are grinding. I used a 3/8 carbide roughing end mill to bring the 10mm dimension closer to finish size so as to not have too much stock to remove. Ran it at 500 rpm, dry, with a pretty aggressive feed taking .010 passes. It ate the hardened steel, with virtually no heat transferred to the coupon. Way faster than grinding! Leaving .003-.005 per side to grind.

Warren! Get better, man!

Hoss, kind thoughts coming your way regarding your health issues. I continue to be educated by the Thomas men and many others here. Thank you so much for that!
Click to expand...

I should get some better end mills. Do you have a recommendation?
 
I didn't even look at the brand Warren, but I will tomorrow. If you have a mill you could machine BEFORE HT, and save some time. Carbide end mills are pretty expensive, but HSS or cobalt should cut coupons before.
 
A quick accountability update:

I said I was going to have samples mailed to Larrin by end of last week, and that did not happen. I seriously underestimated the time to finish grind 99 coupons. I currently have 20 coupons left to be final thickness ground. That will happen tomorrow.

daizee daizee that PSF-27 is wickedly wear resistant when hard. I will pull together the data for you, it will be a couple of days.
20190408_161758.jpg
Michael
 

Attachments

  • 20190408_161758.jpg
    20190408_161758.jpg
    267.8 KB · Views: 1
No problem, Michael. It will all be worth it in the end. Better to do it right. Does that 99 include XHP?
 
99 coupons?? Wow...
Yeah, I bet that PSF27 is brutal on tools when hard. Curious about in comparison to the larger carbides in regular D2.
I hand-sanded a petty gyuto in 154CM last week, and let me tell you, I've finally had enough of THAT. Can't imagine trying that finish on PSF27 :p.
 
Long-time thread lurker here. Some ideas/questions:

What if we all did a group buy on outsourced blanchard/surface grinding on a big lot of coupons? This would allow us to test materials that are significantly thicker than 2.5mm. It seems like the thickness grinding is the primary roadblock to sample production. My main concern here is coupon identification - I don't know how the grinding shop can identify the coupons.

Larrin, what are your thoughts on testing steels that are closer to 50 RC? Do you think your tester will break them, as required to get a result?
 
The charpy tester can do several hundred foot pounds. It will break them.

I'm not sure that grinding from thick material is a limiting factor. Most of the knife steels are available in approximately the right thickness. Some makers use material that is too thin (or that is all that's available). Using stock that is too thick is okay but it does require more grinding as you said, and isn't 100% desirable since more reduction in rolling/forging typically means a finer microstructure.
 
P.Brewster said:
What if we all did a group buy on outsourced blanchard/surface grinding on a big lot of coupons?
Click to expand...
We sent coupons to be blanchard ground. The coolant is a combination of oil & water. Every coupon has a code written on it to identify the alloy and how it was heat treated.

The coolant in the blanchard grinder is very effective at removing permanent and paint pen writing. The process was stopped before all the writing was gone.

Chuck
 
daizee said:
99 coupons?? Wow...
Yeah, I bet that PSF27 is brutal on tools when hard. Curious about in comparison to the larger carbides in regular D2.
I hand-sanded a petty gyuto in 154CM last week, and let me tell you, I've finally had enough of THAT. Can't imagine trying that finish on PSF27 :p.
Click to expand...

With my neuropathy, I’m only belt finishing high alloy steels.

We are over 100 steel conditions now, meaning over 300 coupons. Keeping coupons sorted has been the biggest challenge for me.
 
Alpha Knife Supply said:
We sent coupons to be blanchard ground. The coolant is a combination of oil & water. Every coupon has a code written on it to identify the alloy and how it was heat treated. The coolant in the blanchard grinder is very effective at removing permanent and paint pen writing. The process was stopped before all the writing was gone.

Chuck
Click to expand...

Yup, I'm familiar with the blanchard coolant and its ability to remove markings.

I'm proposing a one-stop shop that has blanchard and surface grinding capabilities, to size the coupons after heat-treating. All 6 surfaces would end up being ground, which leaves nowhere to put a mark. I suppose the (only?) answer is to break up the thickness grinding and width/length grinding into two steps.
 
Willie71 said:
With my neuropathy, I’m only belt finishing high alloy steels.

We are over 100 steel conditions now, meaning over 300 coupons. Keeping coupons sorted has been the biggest challenge for me.
Click to expand...

Unfortunately my hand-finishing techniques were developed before my belt-finishing ones. It's totally catch-up time.

That's a LOT of coupons. I bet an old printing-press-type filing cabinet would do the trick. And so. much. labeling.

You guys are steel heros.
 
I cut longer single coupons that are .120 x 1.5 x 2.75. Using a bandsaw, I cut 3 equal tines from one end leaving them connected on the other end. Use the extra 1/2 inch on the connected end to make markings/#s to keep them separate. After grinding to thickness, use an abrasive saw to trim the excess material and separate the individual coupons and grind the width. Less small pcs to handle this way.

Hoss
 
Coupons are on their way to Larrin.

DevinT said:
I cut longer single coupons that are .120 x 1.5 x 2.75. Using a bandsaw, I cut 3 equal tines from one end leaving them connected on the other end. Use the extra 1/2 inch on the connected end to make markings/#s to keep them separate. After grinding to thickness, use an abrasive saw to trim the excess material and separate the individual coupons and grind the width. Less small pcs to handle this way.

Hoss
Click to expand...

This is a great idea. Are you using a wet saw or cold saw, and if not does it affect the temper? I'm totally on board with making it easier and quicker, I spent days in front of my bandsaw!

Michael
 
You must log in or register to reply here.
Back
Top