A brokeback Robeson

RaptureRaptor

RaptureRaptor

Joined
Jun 2, 2013
Messages
306
A while back I purchased a Robeson redbone from a fellow BF member, when it arrived it was a little lighter than I expected, so I gave it the tea treatment. Unfortunately I forgot about it and three days later I pulled it out to find the back spring snapped clean. I made a gross error and a beautiful knife suffered, leave not your slipjoints open!
 
Leaving a slipjoint open should not break the spring!!
There must be more to the story!!
 
Leaving a slipjoint open should not break the spring!!
There must be more to the story!!
 
waynorth said:
Leaving a slipjoint open should not break the spring!!
There must be more to the story!!
Click to expand...

Leaving the spring open whilst soaking in an acidic solution. the end.
 
I was fairly sure the tea wouldn't be acidic enough for this to happen. The Robeson was 440C stainless, and there was no obvious pitting or the like. I believe I've heard of this happening before somewhere, perhaps the coffee thread. I realise it was dumb, I hadn't intended on leaving it in there that long.
 
I've heard of springs breaking for no reason at all while the knife sits closed. I'd guess the tea was a coincidence.
 
I'm actually a bit surprised. Is this the second story about soaking and a spring breaking that we've had? I do not think that it being open or closed would have had much impact. IF it's really due to the soaking, it would be intergranular stress corrosion cracking or similar mechanism. Basically, in your stainless steels and the type, the "metal" between the grains of stainless are depleted allowing for the cracking. I imagine knives don't get the "best" quality of steel and some of those boundaries may be less protected through the processes required from making the knife.

I am still surprised that a little Tea caused it. A knife is going to spend a whole bunch of time in sweaty acidic pockets and hands.

This is all speculation.
 
Woodrow F Call said:
I'm actually a bit surprised. Is this the second story about soaking and a spring breaking that we've had? I do not think that it being open or closed would have had much impact. IF it's really due to the soaking, it would be intergranular stress corrosion cracking or similar mechanism. Basically, in your stainless steels and the type, the "metal" between the grains of stainless are depleted allowing for the cracking. I imagine knives don't get the "best" quality of steel and some of those boundaries may be less protected through the processes required from making the knife.

I am still surprised that a little Tea caused it. A knife is going to spend a whole bunch of time in sweaty acidic pockets and hands.

This is all speculation.
Click to expand...

Stainless blades doesn't always mean stainless springs, and there is a pretty big difference between being exposed to sweat and being totally immersed in it for days. The most vulnerable part of the spring is generally at the center pin swell on the inside of the handle. A single corrosion pit there can easily weaken the spring enough to cause a failure.
 
yablanowitz said:
Stainless blades doesn't always mean stainless springs, and there is a pretty big difference between being exposed to sweat and being totally immersed in it for days. The most vulnerable part of the spring is generally at the center pin swell on the inside of the handle. A single corrosion pit there can easily weaken the spring enough to cause a failure.
Click to expand...

I agree. I'm just used to seeing stainless springs like Case uses today. Even with the CV blades. If it were a carbon spring, I don't think you would see the break as you need more generalized and substantial corrosion to take place. With the IGSCC in stainless, a lot less metal needs to be affected as you are affecting what's between the grains..... that just seems to make sense in my mind based on my vague memories of school.
 
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