"Sounds like a heat treatment problem."

[Grey Mullet]

Whatever problem someone posts about having with a knife, a common response is "Sounds like a heat treatment problem." I know what heat treatment is, but I want to know if this is really a common problem with knifes from companies with good reputations.

 

[thombrogan]

It can be. Large batches of blades; hundreds or more at a time; going through a large furnace guarantees the blades will reach different temperatures during the heat-treatment process (heating/quenching/tempering/cryo/tempering). Some of the bigger outfits can minimize the variance, but it will still exist. Small shop outfits with in-house heat-treating will be able to do so with less variance, but at a higher cost.

 

[hardheart]

There can be many problems in heat treat. The piece needs to reach austenizing temp, soak for the appropriate time, be quenched rapidly enough for martensitic transformation, and tempered down to desired hardness. Not getting the time or temps right, or consistently across the blade, can cause problems. The steel can exhibit poor properties, or have fractures from the stresses. Lots of things can equal a 'bad heat treat', but I still think some of these blade failures have more to do with the profile/geometry of the knives. Relatively lousy edge holding would be something I'd put to HT.

I don't think any of it is all that common with the better thought of manufacturers.

 

[Esav Benyamin]

Not necessarily a common problem, but then, most problems aren't common, or those companies wouldn't have good reputations. Here on Bladeforums, we get to pick at a lot of what most people wouldn't even notice was wrong.

In any mass-produced line of items, certain samples will be lemons. For whatever reason. There are certain steps along the way that knives can go wrong, and heat treating is one of them.

But if it were common, a whole batch of knives one day, we would expect the company to catch that, even if it might miss a day when only one or two were bad.

 

[Quiet Storm]

One problem is that you can't immediately see whether a knife has received a proper HT or not, while most other blade steel faults you might encounter are either visible right away (such as inappropriate edge geometry for a given task), or they can be determined via simple tests (lack of rust resistance).
Also, as you may have noticed, some people have their favorite "wonder steel" and categorically deny that it might not be all it's cracked up to be. Or they're unwilling to admit that it's not the perfect choice for the type of knife in question; a machete obviously needs a tougher steel than a tiny gentleman folder, while the latter should have superior edge-holding capabilities.

That's why people tend to attribute steel problems they can't or don't want to explain to improper HT.
Of course there will always be "lemons" (as Esav mentioned) that happen to slip past quality control, and I guess that bad HT is one of the easiest things to miss for the QC department.

 

[tirod3]

There is a lot that goes into why one knife cuts better than another. Buck does darn well with 420H, where other makers barely get an edge on better steels. So sometimes it's just easier to blame heat treat, and sometimes it could be. Without a Rockwell test, it's just speculation. With a test, you at least have some data.

Knife sharpening technique, such as leaving a burr, wire edge, or just using too coarse a stone, will allow a knife to dull quickly. Edge angle has a pronounced affect, and what specific combination, for that steel. The user's impression of what they should be able to cut repeatedly before dulling is very subjective without years of experience with lots of other steels. What's under the materials getting cut - as in kitchen cutting boards of ceramic - can influence the issue considerably. So determining what the real problem is, through a question and answer process where both sides don't necessarily have the same definitions and understandings, will leave "heat treat" as the culprit. It's easy to blame, but hard to prove - few people have access to a Rockwell tester, a set of hardness files, or the desire to mark up their blades to find out. And it is a long established fact some makers have left their knife edges thicker and softer to cut down on warranty complaints from users who abuse them prying or tightening screws.