What are the components of the San Mai?

What is the core and what is the jacket?

At few questions in order to give you a decent answer...

1. The exact steel types you're using

2. The laminate process you're using (IE: what steel type is the core, and what steel type is the laminate?)

3. How are you prepping the steels prior to stacking them for welding?

4. Are you trying to forge weld "wet" (with flux), or "dry" (no flux)

Without that information, I can only offer an educated guess..... first, there is a good reason that most of who build this type of steel use "simple" steels.....it's about the expansion/contraction rates of the materials once welded.....if the expansion/contraction rates are not at least somewhat similar, then when the steel is heated or cooled (quenched), one shrinks significantly more then the other.....in other words, it tries to tear itself apart.....obviously, if you have two different steels in a forge welded situation that have dramatically different expansion/contraction properties, and you quench it.....and one steel contracts significantly more then the other, the best you can hope for is severe warping, in the worst case the materials tear themselves apart.

Assuming that you are attempting to use two steels with widely different expansion/contraction characteristics, then even drawing them out is creating issues....one steel doesn't want to "move" under the hammer as much as the other....and you're just inducing more stress by drawing it. You can get away with some drawing, but that tends to be slightly different as to how much you can get away with for each person who makes this type of material.

I soak in hydrochloric to remove scale

I can't say for sure, but I suspect this might be a contributing factor to your issues.....the decarb area(s) of the welds are very likely being eaten away at least somewhat. It would be safer for the billet to grind the scale off. (I do it with an angle grinder)

cold forge hammer marks out

Not something I would do, or recommend doing with laminate steel.

Those are my "best guess" answers based on the information you included in your post..... if you post up the exact steel types you're using, and how they are being stacked/used, along with the other questions I posed, I might be able to help more.

Hi Ed thankyou for helping me and taking the time.The steel I am using is hitachi white number1 and 420 stainless this is from hitachi I haven't welded them myself

Hi Karl thanks for taking time to help I am using Hitachi white number1 and 420 stainless from hitachi I did not weld it they did

OK....so you're working with a steel that somebody else welded.... that makes things difficult, simply because there's no way to know just how good of a job somebody else's welding is. I know 420SS will work, because I've done it, just not with that high of a carbon content in the core steel. I can only give you some ideas on your problems.

If this is a material that is commercially available, and has been used by others successfully, then we have to look at your techniques/methods.

First, I suspect that if you are taking this material and forging it, that is problems #1. When I produce this type of material, I've learned to keep the amount of forging I do on it to a minimum...otherwise bad things tend to happen. For the most part I build/forge weld the laminate billets, using my hydraulic press only (no hammer), and then anneal, and stock remove the remainder of the blade. Experience has taught me that the more you forge this type of material, the more you get multiple, small separations in the weld(s).... I suspect you might be forging it more then the material will tolerate.

Second, This type of material doesn't anneal well in vermiculite. The early billets I made, I tried to anneal in vermiculite, and every single one of them tore themselves apart in the quench. I found that the only way I can get it truly annealed is to put it in a heat treat oven, set it to 1350F for a two hour soak, then allow it to cool down in the oven (generally takes overnight or longer). Once I started annealing in that manner, it ended my problems with blades tearing themselves apart in the quench.

Third, IF the blade are not fully annealed, and you're hammering on them cold, you're likely causing some stress cracking in the welds that isn't visible, and only manifests itself when you quench and the laminates come apart.

Next, I suspect there is a HUGE expansion/contraction difference between the two materials in the quench. Mostly due to the massive differences in the two materials. That means you probably need to back off on the temp you allow the blades to reach when quenching. With as much carbon as Hitachi white #1 contains, you should only have to be in the 1450-1475F range in order to quench....taking it beyond the lower end of it's austinizing range just means that it expands more, and also that it will contract more when quenched...likely causing the blades tearing themselves apart.

OK, all that being said, I strongly suspect that the folks at Hitachi never bothered to do any testing on the material in connection with forging it....it's more then likely that they only did some stock removal type work/testing, and never considered that anybody would forge it. My overall advice would be to stick with stock removing the material, then use their recommended heat treating information as a STARTING POINT to figure out how you can make it work the way you want it to. It's going to take some time, effort and some wrecked blades. But, that's how it has to be done in order to find out what works, and what doesn't with any given steel(s).

This type of material is one of the more fragile combinations (carbon steel with SS laminates) that a person can forge.....and in most cases, the less forging you do it after it's welded, the better.

Karl might know some things about it that I don't....and hopefully he responds, but those are my insights/recommendations.

Hi Edd thankyou so much for your advice it really has been a nightmare I'll try out your advice and see I'll let you know how it goes I can't thankyou enough.

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What are the components of the San Mai?

What is the core and what is the jacket?

Hi Karl I posted earlier but I don't know if you got it first of all thanks for replying my steel is from japan the hitachi factory I have hitachi white number1 with 420 stainless.It is jus tearing apart every quench

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Hi Karl I posted earlier but I don't know if you got it first of all thanks for replying my steel is from japan the hitachi factory I have hitachi white number1 with 420 stainless.It is jus tearing apart every quench

Yes - I saw your reply.

You can tell by Ed's questions and comments that San Mai - especially stainless San Mai - is a highly complex creature.

Doing my own forge welding of my stainless San Mai, I know exactly what to expect. I have no problem forging my ricassos and tangs to shape, but so as to keep my center core in the center on the blade, I saw-cut my blade 'proper' to keep things even from side to side. This I do for appearance purposes more than anything else.

I've many times stated that if you don't trust your stainless San Mai welds enough to forge them down on edge, then you probably should not be selling them to anyone.

Like Ed so accurately stated, your biggest problems are not knowing EXACTLY the quality of the welds, since someone else did them, and you have a huge problem with the expansion/contraction differential of the tool steel core and the stainless jacket. He goes into good detail on this.

It's for this reason that I austenize my San Mai blades in my forge and not my oven. I do not want my full-thick areas up into austentie when I quench.

And I quench in oil.

I have had blades split in two from doing things just not exactly correctly.

Do not think that Ed and I have NOT had many failures. We have.

It's how we learned in our own shops with our own equipment and materials.

Welcome to the world of San Mai.

Thanks Kal and Edd thanks for you time and experience I am going to take on board your very well received advice and will let you know how it goes thanks again

are the welds popping or is it the core splitting, I have had both happen.

For the core splitting is due to the core turning to martensite and the outer layers not as martensite is larger it expands the outer can not and the tension goes into puling the core apart. couple of things that help with that are extra normalizing, interrupting the quench at around 500deg and going into temper Immediately like don't even get to room temp, get it in as soon as it turns over to martensite.

MP

Thank you Mathew it tearing the core apart grain structure looks perfect. Thanks for helping i will experiment and get back.Thanks for taking the time to answer it's much appreciated.

i have not done any stainless san mai, however I have made 1 successful san mai using i think it was a problay 1/8th inch piece of w-1(it may have been O-1 as i had both in stock at the time) bar i made from hammering down a piece of round stock, and low carbon angle iron from the hardware store. like you i only hand hammers to set the weld as i do not have a power hammer or press...yet. however i also have several types of them from a 3 pound engineer hammer to a small 4 ounce ball peen hammer. i think i use my 2 pound Stanley "black smiths" hammer to set the welds. as setting a weld is not about power but insted about just working the 3 pieces together and from a few videos and experience making a san mai from scratch, hitting something to hard when forge welding will just cause the weld to give out every time. you need to be gentle like you would be with a new born baby well setting a weld, then once its properly set, you can smash that piece of steel like the hulk did to loki in avengers. (i was going to go in a diffrent direction but it just sounded too dirty to put up on a semi public form like this.) to check to see if the weld is propperly set cut off a small section of one end of the piece to see if they look like one piece of steel

However, i have also failed 2 times using 52100. what i have learned so far is its tricky to fit a low alloy steel like Hitachi white with a high chromium steel like the 400 series stainless. however, i also think your just not getting it set properly as even though its a prefab material it's weld may not be fully set. I would get it nice and white hot a few times and hammer on it to better set the ingot( i dont really like the sound of the word billet for some reason) and getting it white hot and setting it's weld better is not a bad thing. like with hammering a edge you want to do the same thing you did on one side to the other. also i would dip a end in a echent long enough for you to be able to see just how thick the 440 lairs are to the Hitachi as this will allow you to tell how thick each component is, which will allow you to better judge were high carbon core is in that piece of steel once you star forging.

also i would grind off the forge scale cause as long as you have some of the 'jacket' on the steel it should function properly and it will give the blade a very cool pattern once the blade has been etched. in my humble opinion a san mai line is even cooler then that of a hamon line do to the simple fact that (i think) it really can never be reproduced like with a hamon as the moving of the steel can not be duplicated exactly do suttle differences caused when setting your weld.

However i am also just an apprentice myself so i am not a expert out there when it comes to forge welding.