Dishwasher ruining temper??

Codger_64

Codger_64

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I had never heard of this and it sounds dubious to me. I figured that if anyone here on BF would know about tempering, it would be you fellows. Feel free to move this if it is posted in the wrong forum.

Orpheous said:
Just what I'd read, I haven't put any of my kitchen knives in the dishwasher for years, I hate hearing them rattling around in there! Dishwashers run at up to 180 degrees f (about 82 degrees c), I wouldn't trust a razor edge with that temperature either...
quote from key-to-steel
(this information refers to tempering, also relevant to de-tempering)
"Changes during tempering
The principles underlying the tempering of quenched steels have a close similarity to those of precipitation hardening. The overlapping changes, which occur when high carbon martensite is tempered, are shown in Fig. 2 and as follows:​
Stage 1. 50-200°C. Martensite breaks down to a transition precipitate known as c-carbide (Fe2,4C) across twins and a low carbon martensite which results in slight dispersion hardening, decrease in volume and electrical resistance."

​
quote from cutlerscove
"Never use a dishwasher for cleaning your good knives (kitchen or other wise). Doing so could possibly remove the temper from the edge and render the blade soft so it will not hold an edge."

quote from chefsarmoury
"Never wash your knife in the dishwasher. The harsh chemicals and hot temperature will ruin the quality of the blade."
Click to expand...

Opinions? :confused:

I can't see how this temperature range would affect good tempered steel, but I am a user, not a maker.

Codger
 
Temperatures of even boiling water will not change the temper. The blades would have originally been tempered at 400 F or higher. The harsh detergents and heat may however damage some handle materials. It's somewhat of a moot point since it takes only a very few seconds to clean a knife !! ...what's a dishwashing machine ???
 
i see it as more of a banging around in the washer and the harsh chemicals "eating " at the edge

my stainless kitchen knives are tempered at 400F for 4 hours and my cpm3v blades 1000f for 6 hours i might be wrong but i cant see how the washer temperature would be hurting most steels
 
Timken has bearing that were made in the 1950's still operating that have experienced temperatures in those ranges for years without a signicant impact on the hardness of the steel. At about 200 degrees F., you might begin to see some metalurgical changes, but this would take quite a while to happen at that low of a temperature. We state in our literature that you can heat a bearing to 300 degrees F. for 4 hours without significantly impacting the heat treatment, 250 degrees F. for 8 hours and 200 degrees F. for 16 hours. This is for case carburized steels.

For 52100 steel we suggest a maximum temperature of 250 degrees F. for 4 hours, 225 degrees F. for 8 hours and 200 degrees F. for 16 hours. As you can see, 180 degrees F., no matter how long it is exposed to that temperature, isn't even a concern for us with any of these steels.

Just my .02 cents worth.
 
I dont personally see that the temperature alone could be an issue, particularly with regard to 'de-tempering a blade.

Chemicals used are not drastically harsh, but are apparently somewhat corrosive. As in most cases with chemicals, the application of heat at the same time can increase the corrosive activity almost exponentially, and the edge is particularly vulnerable to corrosion. Bear in mind that the exposure is a short period and it will probably take many washes to have a noticeable effect.

Having a handful of sharp knives (particulalry the edges) banging against each during the wash cycle is probably your biggest concern, and the issue most likelt to cause damage.

Lang
 
As far as I'm concerned, the blade will suffer no more harm in the dish asher than in the knife block. The handle and any glues used are another story. Of course, if the blade is carbon steel, the hot caustic water will affect the edge by corrosion, but not by detempering.

I always give a sheet of care instructions with kitchen knives. It says to hand wash and dry as soon as is practical after use.
Stacy
 
I agree that the dish washer is no place for a decent knife. A good wipe with a cloth and hot water is normally enough to clean a smooth blade if not a little soap ant then a hot rinse. A cloth with a bit of olive oil by the block for a finally wipe before storing would be a good touch.

on a side note. I made a kitchen knife of high carbon and gave it to the wife and said no dish washer. She leaves it lay around with all kinds of stuff on it often for hours or over night before wiping. I think I may put her in charge of my patina department. She has done a great job on it. LOL
 
ib2v4u said:
I agree that the dish washer is no place for a decent knife. A good wipe with a cloth and hot water is normally enough to clean a smooth blade if not a little soap ant then a hot rinse. A cloth with a bit of olive oil by the block for a finally wipe before storing would be a good touch.

on a side note. I made a kitchen knife of high carbon and gave it to the wife and said no dish washer. She leaves it lay around with all kinds of stuff on it often for hours or over night before wiping. I think I may put her in charge of my patina department. She has done a great job on it. LOL
Click to expand...

IB2v4U
I think we could start an entirely new subforum with all the "look what my wife did to the knife I made her" horror stories we all have.....:(
Matt
 
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