Two 1095 questions for experts

[BluntCut MetalWorks]

When comparing hardened steels performance in a wide spectrum of edge applications, perhaps best to focus at steel optimal ht microstructure rather than slog through mountain of data on instances and group of instances per steel. Also keep other variables (profile, geometry, hrc, etc..) the same.

Optimally hardened 1095 has a slight advantage over good ht 3V in thinnest edge stability, trail on wear & corrosion resistant. Here is an excerp of my yt response to Cliff Stamp about W2 vs 4V.

ref: https://youtu.be/vkWtqkW3UHY

4V and other high alloyed steels are higher heterogeneity microstructure as a whole than W2. Heterogeneity is a self feeding behavior when hardening, which spiral toward higher heterogeneity (RA; carbide+precip_carbide coarsending; freed ferrite). heterogeneity may register higher reading in hrc because intrinsic high dislocation, especially in high irregularities in grain & carbide boundaries/interfaces.

These high alloyed steels are inherently brittle even in lower hardness. Once plastic flow caused particle pileup (it's a jammed situation because of irregular shape particles interlocked each other), cracking force will propagate.

W2/52100/etc has smaller particles (grain, carbide & crystal cells), thus pileup volume is larger. Implied wider volume/band of propagation, hence bigger impact load. The 67.25rc W2 blade had big chip (and the 65rc blade too) both received poor strikes/batons with high rebounced, most important aspect I look for is the radius of damage (from point of impact). Global/cascade is bad - as in case of 4V.

In term material fracturing efficency, thinnest apex radius + cutting wedge shape with highest stability and retention win. Fracturing approach (cutting/chopping) style & material hardness/abrasive affect retention outcome, so there are certain amount of tailoring on microstructure (heterogeneity or Homogeneity) depend on applications. Master ht of low alloyed steels is a necessity foundation. Sometime, I look at 3V/M4/etc as microwave readied dinner packages 
​

My current attempt to produce higher homogeneity(by reducing carbide size) microstructure for D2 & 3V. Even though hted 3V only has around 2.8% carbide volume but like many PM steels - carbide dia in 2-4um is cube root less population than steels with nominal carbide dia in sub 500nm range.
http://www.bladeforums.com/forums/s...chopping-impact-tests?p=15943800#post15943800

Why D2? because it is well known for having low toughness. So, I have to show a few instances of D2 high edge stability at 63-64rc.

 

[RX-79G]

Double post. 524 timeout error.

 

[RX-79G]

To say differential hardening/tempering is unnecessary and sometimes lead to lower quality product is just totally ignorance.

People like Jerry Fisk, Adam DesRosiers, Burt Foster, Jason Knight and many more who considered to be one of the finest knife makers among the world are still doing what you called unnecessary and might lower product quality...

It's funny seeing people arguing steel performance just base on only composition or industrial graph
pretty much like judging the quality of beer just from it alcohol or ingredient content

I had thought I had phrased this the right way, but I clearly did not:
Steel usually exists in either pearlite, bainite or marstenite form after you heat it up and let it cool fairly rapidly. Marstenite is the form all the charts are built out of, showing the high strengths and hardnesses we associate with high carbon steel. Differential hardening leaves half the blade in pearlite form, which is indeed able to withstand more bending because it is soft and weak.

There is no industrial application I know of where high carbon steel is left partially in pearlite form. It is a poor way to use steel when you are able to make an object that is all marstenite or bainite and have some real strength. However, custom knives are not "industrial applications" of steel; the metallurgy and structure don't have to be perfect to work very well, and the appeal of differential hardening is as much historical and aesthetic as anything else. I have done it myself because it is neato - but it is more of a stunt than an engineering process, especially considering the higher likelihood of failure during quench the process causes.

What I said otherwise was "Differential tempering is a more modern, and sometimes very controlled, way to heat treat... It is generally unnecessary and sometimes makes a lower quality product." So that quote is about differential tempering, not not differential hardening and I was speaking about the range of methods of doing so, some of which sometimes are a bit haphazard because they are quick and somewhat uncontrolled.


You can make a very nice, sharp durable piece of cutlery out of a leaf spring, sand iron, whatever. My first forged blade was 1095 heated in a forge, the temp controlled with a magnet, I did not soak at temp before quenching in water. I didn't get it into the tempering oven for another 6 hours later. The blade I made looks great, cuts well and holds a good edge. In other words, I did everything wrong and it came out seeming just fine - processed an entire deer and still haven't sharpened it. That isn't because I'm a genius, it is because even getting 80% out of a steel will still make a reasonable knife. People who are geniuses with metal could have done much better with the same tools, and there's nothing wrong with buying and using such a knife. I just don't think anyone should tell themselves that they got better metallurgy because of process based on human judgments rather than a thermocouple. Better knife overall? That's a different question.

Those charts are based on doing things the right way, and it is definitely true that certain alloys, like 52100 and D2, have benefited from more precise HT formulas than industry standards. But they don't benefit from less control than industry standards.

 

[RX-79G]

Interesting,none of these types of charts show RC.3v for example toughness changes night and day from 58 to 62 RC.
They need to show RC of each steel and make better charts.

From the listed stats,think Barkriver Senegal is chippy...just from listed RC and knowing how A2 acts?

They do make such charts:

I haven't been able to find a 1095 version, but all the tool steels are represented - usually in even finer increments.


To address your 1095 vs. CV question, if the two steels are HT'd to about the same wear resistance, the only way you're going to notice the difference between them is if you bang them hard enough to chip the more brittle of the two. Up to that point, they will seem very similar. The difference between steels is sometimes what they do when pushed to the extremes, not before.

 

[farmer ted]

To say differential hardening/tempering is unnecessary and sometimes lead to lower quality product is just totally ignorance.

People like Jerry Fisk, Adam DesRosiers, Burt Foster, Jason Knight and many more who considered to be one of the finest knife makers among the world are still doing what you called unnecessary and might lower product quality...

It's funny seeing people arguing steel performance just base on only composition or industrial graph
pretty much like judging the quality of beer just from it alcohol or ingredient content

Some people want to make a Civic into a fast car, others will purpose build a fast car. Start with the materials that are designed for your application, instead of tweaking a material to your application.

 

[shqxk]

I had thought I had phrased this the right way, but I clearly did not:
Steel usually exists in either pearlite, bainite or marstenite form after you heat it up and let it cool fairly rapidly. Marstenite is the form all the charts are built out of, showing the high strengths and hardnesses we associate with high carbon steel. Differential hardening leaves half the blade in pearlite form, which is indeed able to withstand more bending because it is soft and weak.

There is no industrial application I know of where high carbon steel is left partially in pearlite form. It is a poor way to use steel when you are able to make an object that is all marstenite or bainite and have some real strength. However, custom knives are not "industrial applications" of steel; the metallurgy and structure don't have to be perfect to work very well, and the appeal of differential hardening is as much historical and aesthetic as anything else. I have done it myself because it is neato - but it is more of a stunt than an engineering process, especially considering the higher likelihood of failure during quench the process causes.

What I said otherwise was "Differential tempering is a more modern, and sometimes very controlled, way to heat treat... It is generally unnecessary and sometimes makes a lower quality product." So that quote is about differential tempering, not not differential hardening and I was speaking about the range of methods of doing so, some of which sometimes are a bit haphazard because they are quick and somewhat uncontrolled.


You can make a very nice, sharp durable piece of cutlery out of a leaf spring, sand iron, whatever. My first forged blade was 1095 heated in a forge, the temp controlled with a magnet, I did not soak at temp before quenching in water. I didn't get it into the tempering oven for another 6 hours later. The blade I made looks great, cuts well and holds a good edge. In other words, I did everything wrong and it came out seeming just fine - processed an entire deer and still haven't sharpened it. That isn't because I'm a genius, it is because even getting 80% out of a steel will still make a reasonable knife. People who are geniuses with metal could have done much better with the same tools, and there's nothing wrong with buying and using such a knife. I just don't think anyone should tell themselves that they got better metallurgy because of process based on human judgments rather than a thermocouple. Better knife overall? That's a different question.

Those charts are based on doing things the right way, and it is definitely true that certain alloys, like 52100 and D2, have benefited from more precise HT formulas than industry standards. But they don't benefit from less control than industry standards.

The heat treatment and steel phase relation are much more complicate than what you are talking... Its just not that simple.
There are different type of martensite, the good one and bad one... same as pearlite and others phase. There are also carbide size to grain size...

The main reason for differential hardening/tempering is for a tougher blade because both pearlite and spring tempered martensite are much tougher than 400F temperted martensite.

This benefit of this method will be see obviously in application like sword, heavy chopper or machete. Especially the one with acute profile like most custom... through hardened steel will have higher chance to breakage compare to one with differential HT, obviously.

Some people who love to theorize might say its sacrifice strength.. but in reality only stupid people who use knife for prying. And even at prying, the through hardened one will broke first.

And I don't think you get anywhere as high as 80% of 1095 with what you did. 1095 is not a very forgiving steel and need precise temperature at austenitizing. Non magnetic start at 1420F for plain carbon therefore another 55F is just depend on your eye... unless you are a very experienced maker which you obviously didn't you will 99% miss the temperature.

Every steel benefited from more precise HT even one which the most forgiving like 1080.

Almost every knife makers I know do have oven with digital control thermocouple. Its just a very common tool and nothing to be brag about...
I bet there are very few makers who still guess the temp by eye nowadays.

 

[RX-79G]

The heat treatment and steel phase relation are much more complicate than what you are talking... Its just not that simple.
There are different type of martensite, the good one and bad one... same as pearlite and others phase. There are also carbide size to grain size...

The main reason for differential hardening/tempering is for a tougher blade because both pearlite and spring tempered martensite are much tougher than 400F temperted martensite.

This benefit of this method will be see obviously in application like sword, heavy chopper or machete. Especially the one with acute profile like most custom... through hardened steel will have higher chance to breakage compare to one with differential HT, obviously.

Some people who love to theorize might say its sacrifice strength.. but in reality only stupid people who use knife for prying. And even at prying, the through hardened one will broke first.

And I don't think you get anywhere as high as 80% of 1095 with what you did. 1095 is not a very forgiving steel and need precise temperature at austenitizing. Non magnetic start at 1420F for plain carbon therefore another 55F is just depend on your eye... unless you are a very experienced maker which you obviously didn't you will 99% miss the temperature.

Every steel benefited from more precise HT even one which the most forgiving like 1080.

Almost every knife makers I know do have oven with digital control thermocouple. Its just a very common tool and nothing to be brag about...
I bet there are very few makers who still guess the temp by eye nowadays.

It sounds like you know more about this than your objection made it sound. I also tried to keep it simple, but I still think a differentially tempered sword makes more sense than one loaded with pearlite.

 

[shqxk]

Some people want to make a Civic into a fast car, others will purpose build a fast car. Start with the materials that are designed for your application, instead of tweaking a material to your application.

Care to explain what is the material designed for each application when it come to knife steel?

Do you believe those makers don't have knowledge or budget to spent on newer steel or equipment to grill them?

I have ever talked to Daniel Winkler asking him about 3V vs 80CRV2 in hard use and he told me that people wouldn't even notice the difference except the higher corrosion resistance of 3V and ease of sharpening of 80CRV2.
80CRV2 is actually just 1080 with a hint of V and Cr you know?

3 Weak ago I made a machete out of CPM-3V with very expensive HT protocol. The toughness and edge holding is excellent but I start to feel regret now because I realize that proper HT 5160 will do 80% of it performace at 1/5 price... The overall design and geometry are just far more importance than steel type.

Those color on the blade are made by quenching 1980F steel in 500F molten salt.

 

[RX-79G]

Saying 80CrV2 is "just 1080 with a dash" completely misses how powerful alloying is. 80CrV2 is most closely compared to 5160 and L6, two of the toughest steels available. The fact that 3V produces high toughness through rich alloying doesn't mean that low alloys don't also produce very tough, useful knives.

 

[shqxk]

Saying 80CrV2 is "just 1080 with a dash" completely misses how powerful alloying is. 80CrV2 is most closely compared to 5160 and L6, two of the toughest steels available. The fact that 3V produces high toughness through rich alloying doesn't mean that low alloys don't also produce very tough, useful knives.

Yes I know that even a hint of alloy does make huge different.

80CRV2 are closer to 1080 because of its carbon content. It actually named as 1080+ before.
The .5% Cr and .2%V are for pinning grain boundaries at austenitizng for finer grain therefore high likely to be tougher than other 0.8% carbon steel at the plus of better wear resistance too.

Some people compare it to 5160/L6 because it remarkable toughness.

 

[RX-79G]

That chart does not include CPM154. it is quite interesting to see how much toughness that steel gains though use of the PM process compared to regular 154CM which is listed on this chart. IIRC, the abrasion resistance stays he same, but the toughness exceeds that of S35VN. which is a bit higher than S30V. Also, the apparent difference between the toughness levels for 3V on the two charts that have been posted is likely due to hardness. IIRC, this chart is showing the toughness for 3V at 58Rc where is is around 2.5 times as tough as A2 at 60Rc. That gap closes when you take the 3V up to 60Rc using the "factory spec' teeming instructions.

I'm also really curious how CPM D2 works. For that matter, what would CPM 1095, A2 or L6 look like? The PM process increases toughness all around, so it would be fascinating to see what happens to simple steels when subjected to that process.

I also haven't been able to find much on how Hitachi White and Blue steel are produced, but it sounds like it may be a process that bears a resemblance to PM, or have similar benefits.

 

[RX-79G]

Yes I know that even a hint of alloy does make huge different.

80CRV2 are closer to 1080 because of its carbon content. It actually named as 1080+ before.
The .5% Cr and .2%V are for pinning grain boundaries at austenitizng for finer grain therefore high likely to be tougher than other 0.8% carbon steel at the plus of better wear resistance too.

Some people compare it to 5160/L6 because it remarkable toughness.

But no one is comparing 1080 to 5160/L6. It's tough, but not tough like 5160, L6 or 80CrV2. Those three share a lot of chemistry, which give them both toughness and edge holding exceeding any of the 10xx steels. There's no other reason for them to exist.

 

[shqxk]

I'm also really curious how CPM D2 works. For that matter, what would CPM 1095, A2 or L6 look like? The PM process increases toughness all around, so it would be fascinating to see what happens to simple steels when subjected to that process.

I also haven't been able to find much on how Hitachi White and Blue steel are produced, but it sounds like it may be a process that bears a resemblance to PM, or have similar benefits.

1095 and L6 wouldn't benefit from PM process since they are already fine grain as it can be. It fact, these 2 steel might have finer grain than any PM alloy steel because it has very little to no alloy to mess with from the first place.

If you want to refined grain of these steel without affecting the hardenability then adding carbide former like vanadium might help because it will aid on pinning aus-grain.

There are 1095FG which is 1095 with a hint of Vanadium if you want to try though.

 

[REVDH]

People use the word tough differently. Some people think of it as hardness and edge retention. But ost people consider toughness as the flexability and resistance to breaking. These people that say 1095 is no tough are probably referring to the first definition. 1095 does not hold the best edge, but it does get and hold a damn good one for a while.

 

[RX-79G]

1095 and L6 wouldn't benefit from PM process since they are already fine grain as it can be. It fact, these 2 steel might have finer grain than any PM alloy steel because it has very little to no alloy to mess with from the first place.

If you want to refined grain of these steel without affecting the hardenability then adding carbide former like vanadium might help because it will aid on pinning aus-grain.

There are 1095FG which is 1095 with a hint of Vanadium if you want to try though.

I disagree with you about 1095. 1095 makes cemetite carbides that are large and uneven compared to chromium or vanadium carbides. If it produced a very fine grain it would be a very tough steel, but it does not and is not. 1080, which doesn't have enough extra carbon to produce cemetite is a finer grained steel.

 

[Marine E7]

Great chart !
Thanks RX !

 

[RX-79G]

People use the word tough differently. Some people think of it as hardness and edge retention. But ost people consider toughness as the flexability and resistance to breaking. These people that say 1095 is no tough are probably referring to the first definition. 1095 does not hold the best edge, but it does get and hold a damn good one for a while.

Not to be a definition ninja, but toughness has a specific meaning, and it is usually the opposite of hardness or edge retention. Some of the hardest, best slicing and long wearing blades are glass, used in labs. They have almost no toughness.


The "miracle" of alloying is that you can up something like edge retention without sacrificing another factor, like toughness. That's because you can introduce structures in the steel that are harder AND help the refine the grain for toughness at the same time.

 

[me2]

I'm also really curious how CPM D2 works. For that matter, what would CPM 1095, A2 or L6 look like? The PM process increases toughness all around, so it would be fascinating to see what happens to simple steels when subjected to that process.

I also haven't been able to find much on how Hitachi White and Blue steel are produced, but it sounds like it may be a process that bears a resemblance to PM, or have similar benefits.

I think there is a lot of misunderstanding about what the CPM process does and why it was developed. It reduces carbide segregation in steels with very high alloy content. Steels like S90V would not be feasible without it. Steels like 154 and D2 have a large enough carbide volume that they benefit by reducing segregation. CPM steels have a more consistent hardening response, better rough machinability, and more consistent wear response compared to non CPM versions. The toughness of CPM versions of the same steel isn't necessarily better on average, but the highs and lows will be more consistent.

 

[RX-79G]

I think there is a lot of misunderstanding about what the CPM process does and why it was developed. It reduces carbide segregation in steels with very high alloy content. Steels like S90V would not be feasible without it. Steels like 154 and D2 have a large enough carbide volume that they benefit by reducing segregation. CPM steels have a more consistent hardening response, better rough machinability, and more consistent wear response compared to non CPM versions. The toughness of CPM versions of the same steel isn't necessarily better on average, but the highs and lows will be more consistent.

Agreed. I was more getting at how interesting it would be to see how much different even a very basic steel could be through the PM process. But I also think that 3V wouldn't seem quite as stellar if A2 were available in a PM version.

So sometimes PM is a necessity just to be able to produce the alloy and make anything out of it, and sometimes it give steels like D2 and 154CM a boost. Maybe 1080 PM would be a waste of time, but it might make 1080 act like a tool steel. I couldn't begin to guess.

 

[jdm61]

Hitachi steels are just SUPER clean/pure with VERY low amounts of the bad "alloying elements" sulphur and phosphorus. They are cast steels.

I'm also really curious how CPM D2 works. For that matter, what would CPM 1095, A2 or L6 look like? The PM process increases toughness all around, so it would be fascinating to see what happens to simple steels when subjected to that process.

I also haven't been able to find much on how Hitachi White and Blue steel are produced, but it sounds like it may be a process that bears a resemblance to PM, or have similar benefits.