First san-mai weld

[Natlek]

Well , few hours earlier I would not believe that it would turn out this way . The core is perfectly centered ,no sign of not welded part at all . Core is 1.5mm 1.2519 carbon steel and for side I use 1.2mm 304 stainless . 1.2519 was hardened /63-65 hrc/ before welding with 304 stainless .For welding I use basic 316 welding rod . Now I can say that it was easy , maybe to easy .I hope that I will repeat it successfully again .I use very light blows with a hammer for welding . It turned out that my small tube furnace was made up for tasks like this , it warms the steel to a temperature extremely fast . I do job in three heating with very short soak time . Welding temperature was 1200 Celisus . I have some question guys , if you don't mind ?
Which is lowest temperature for welding ?
How to clean this stainless without grinding ? I want to leave it as it is now ?
How to normalize this steel ? What protocol you recommend ?
And what you think if I HT /quench / as it is now ? Would the core get hard as it need to get ? Or it is better if I grind bevels and harden after that ?

Spine side after welding with 316 rod three steel together.....

This is moment when I say God help me .....when i was think that all is done

And it was done , thanks God
3.7mm beauty

spine side

edge side ..

How to get back grain in condition they are before welding is now most important to me .I have no idea with which temperature to start , how long to soak ... etc . So please help

 

[John mc c]

Looks good natlek
I can't help with any of your questions tho as I don't know but can I ask where you got the 1.5mm 1.2519?
I can only get 1.2419 in that size

 

[Natlek]

Looks good natlek
I can't help with any of your questions tho as I don't know but can I ask where you got the 1.5mm 1.2519?
I can only get 1.2419 in that size

Thanks !
There was tobacco/cigarette factory in my town.....from there I get that steel . they come in 1.4mm , 1.5mm and rare in 1.8mm .Some of them are from Ravne ,Slovenia .
When they are new they look like this , but hard to get them new . I can get thousands worn out like this on picture and most time they have enough width to make kitchen knife...

OK , what you guys think about this normalizing process ??
870 celsius 5min.
850 Celsius 5min.
830 Celsius 5min.
830 Celsius 5min. QUENCH !

 

[Natlek]

Looks good natlek
I can't help with any of your questions tho as I don't know but can I ask where you got the 1.5mm 1.2519?
I can only get 1.2419 in that size

Well , that steel in my pictures is surface grind after HT so from there must be this no standard thickness ?
This is 1.8mm 1.2519 from Slovenia , it is almost mirror finish surface

 

[Natlek]

I always forget to thank those who have contributed in every new and successful project I do in my knife adventure .
So thanks to everyone who selflessly shared their knowledge here on BF and help us to master some techniques in faster and easier way
I etch in vinegar this san mai , looks good to me .
I think I need to explain how I do it . From previous work /straightening ball bearing steel/ I learn this ........don t put whole bullet on anvil ,just part on which you work at moment , then move it .It will keep temperature longer .That s how I do it for welding this san mai .It is relative thin so it loose temp. fast . I hold hammer right to the head so i have more control to hit steel in right way to not make deep indentations. I still can not believe how light strike with hammer successfully welded this . Obviously temperature , clean steel , light hammering and completely sealed/weld is most important .
Thanks guys again now I need to make knife from this

 

[Ken H>]

That looks really good 'n centered - congrats on your San Mai. A really good job of keeping core centered.

You asked about welding temps - for SS cladding as you have, I've found 1200C to 1250C works good for me. This was based on Stacy (and a couple other folks) advice. low carbon steel cladding can be in the 1150C range.

Why did you harden the high carbon core before welding?

I've always drawn out and ground the billet until it was the thickness I wanted to use for the blade, then profile the blade and do HT'ing before any bevel grinding. With the SS cladding I've quenched in water (only really fast quench I've got). The SS cladding slows the water down enough so there doesn't seem to be any problem with cracking of core.

 

[Natlek]

Thanks Ken I was afraid that I weld on to high temp On second weld i flip sides , i was thinking that can help to keep all centered ?About carbon steel , I didn't harden it .It was already hardened planer blade from tobacco industry ,so ..............
Well I normalize it /I think/ , 870 , 850 and 830 several times .And it survived quenching/from 800 celsius/ in slightly warm pure water BUT i forget that blank have slight bend and to take care of that before quenching......... so it slightly bends ,but not sigh of delaminated part .I read that blade can delaminated when quenching ?
I make another short soak on 800 celsius .... I will HT it again tomorrow

 

[Natlek]

Almost got an infarct last night After tempering there was delaminated/crack on spine and edge side right in middle of carbon steel Sayonara san mai....... Luckily it was very shallow , about 1mm deep on bot side .I grind both side and they disappeared . ..I do anything by rule , quench from 800 Celsius in warm water , tempering oven was already on 180 Celsius ,blade was warm when goes in tempering oven , I hold it with pliers .............. ?? Is this normal ? I mean it is 304 on side ?? I read lot of about this san mai problem but in most case it happens when both are carbon steel ?
I grind little one side free hand to see what i have .......I like it
cracks was where red lines are ........... ?? I m 100% sure that they are not there after quenching ....blade was clean so i would see them , they show up after tempering ??

 

[John mc c]

Why warm water quench natlek?
Would warm oil be easier on welds?
That's how I quench my 1.2519

 

[Natlek]

Why warm water quench natlek?
Would warm oil be easier on welds?
That's how I quench my 1.2519

Warm water is less violent to steel .I decide to use water because of soft 304 cladding . I quench from 800 celsius .I don t think that that small crack are from water quench.....
Welds are fine , cracks was in middle of 1.2519 .Just as you try to split it in two ....

Harden from a temperature of 780-820oC, 800-860oC followed by water or oil quenching. Hardness after quenching is min. 64-65 HRC.

https://steelselector.sij.si/steels/OW3.html

 

[John mc c]

Ok.
I tend not to follow those general steel guidelines,I've often read on those to water or oil quench yet I know the steel I be using usually cracks in water

 

[Natlek]

This was second quench .It survive first quench with out problem , but was slightly bent and I make quick decision and put it back in oven on 800 celsius ...... before it coll down. Maybe this was reason .....................I have slightly weld remain on tip and on both corners at end of blade .It was rough shape , more surface less worry , that s way tang is not shaped...

 

[Natlek]

OK , I m ready for second one .This time 416 with 1.2519 ............... Inside fit copy of Falkniven F1 , I have extra about 4mm steel all around . This one will be for my son ...I hope

I was thinking about that cracks that show on first one ....Guys , every blank I HT and temper have raised edges.I mean when I start to hand sand blank to clean it after HT I notice that edges all around blank is raised and sandpaper catch only there ..........that mean that steel expand more on edge ? I m 100 % sure about raised edges after HT .I try in this drawing to explain how blank looks after HT .Red line is expanded steel on edges.... So I was thinking ,is it possible that crack start just because that , because edges expand more then rest of steel ?
I was thinking to grind blank before I HT like on picture , on right side on drawing .Maybe that will help to avoid delamination in middle of core , edges are free to expand ? After first one , I m afraid that i can end up with two blanks .....with two mono-mai
What do you think about this ?

 

[A.McPherson]

Why are you profiling first?

I think you'd get better results with just rectangles... Easier to arc weld before you start forge welding.

 

[Ken H>]

Natlek, I know you like to do things YOUR way, but from all the reading I've done, and is confirmed with the few San Mai billets I've made, both low carbon cladding and 416 cladding it's pretty common to have delams and bad welds in the first 1/4" (5mm?) around the edges. For that reason I've always made rectangle billets large enough to have at least 1/4" to remove all the way around if needed to clean up the billet.

Also, you mentioned HT'ing the core to 64 Rc before welding up in billet - why?

 

[Natlek]

Why are you profiling first?

I think you'd get better results with just rectangles... Easier to arc weld before you start forge welding.

I must keep dimension small as I can because opening in my tube furnace is only 40 millimeters .....Plus , more compact less chance to screw it up with hammer I m almost done with another one tube furnace with 65 millimeters inner Dia. I like how fast they heat steel inside and because temperature don t drop at all with open door ... perfect for job like this one .

 

[Natlek]

Natlek, I know you like to do things YOUR way, but from all the reading I've done, and is confirmed with the few San Mai billets I've made, both low carbon cladding and 416 cladding it's pretty common to have delams and bad welds in the first 1/4" (5mm?) around the edges. For that reason I've always made rectangle billets large enough to have at least 1/4" to remove all the way around if needed to clean up the billet.

Also, you mentioned HT'ing the core to 64 Rc before welding up in billet - why?

Ken, I don t HT the core , it is blade from tobacco industry already HT ....I don t see problem with that it is HT-ed...This 2.2mm core is annealed steel .
Ken , I m not afraid of delams and bad welds.............I m afraid of crack right in middle of carbon steel ? I have crack right in middle of core , luckily very shallow this time .Look this picture from net ......nightmare

I m not sure why is this happening ? Core is free to expand between that two layer of stainless ? Maybe carbon migration have some role in that ? Technically we have core with different carbon content inside ? More carbon in middle lover carbon on sides ??
I notice on first one that I have about 1-2mm HARD stainless ,just right up the dividing line ? 304 stainless need lot of carbon to do that ?

 

[chumaman]

Sorry mate I couldn't resist, this song instantly popped into my head

And the name of that music genre is Nu Metal

 

[Ken H>]

OK, now I understand the 64 Rc, that's the way you received the metal, NOT that you HT'd it to get 64 Rc. Makes sense now.

I have seen that exact split in a couple of threads in past. Seems like the cause was something to do with the core alloy having too much different expansion rate than the cladding metal. It created quite a thread at the time. That last photo is really impressive the way it split.

 

[Natlek]

OK, now I understand the 64 Rc, that's the way you received the metal, NOT that you HT'd it to get 64 Rc. Makes sense now.

I have seen that exact split in a couple of threads in past. Seems like the cause was something to do with the core alloy having too much different expansion rate than the cladding metal. It created quite a thread at the time. That last photo is really impressive the way it split.

There must be the safe way to overcome this problem .Lot of work and preparation ...and to end up with TWO blade is not good for my health I don t think that Japanese cross fingers when they make san mai ?