Heat treating 01 tool steel knife

It was the main tool steel used other than simple carbon steel for about 25 years. Prior to the work of Taylor and White in the development of high speed steel, there was some evolution of alloying, particularly with testing different combinations of Mn, Cr, and W.

In the decade , experiments in France were being conducted on chromium-alloyed steels. And by there were some studies on low alloyed steels with a combination of chromium and tungsten.

By there is record of a steel with a somewhat similar composition to O1 produced by Brooklyn Chrome Steel Works. Therefore O1 looks more like those earlier era steels which were not being explored specifically for high speed applications.

The earliest reported composition I found for O1 is from [7], it is hard to say how much it might have changed between and There is a potential alternate evolution to O1.

The Mn was then later partially replaced by 0. However, I cannot find a composition for Ketos that shows it as anything other than as O1 not O2, so it would have changed pretty early on. But if the account is accurate then John A. Mathews developed both of the common oil hardening steel types: O1 and O2. Because Ketos was very popular most of the major steel manufacturers developed their own versions by at least These versions ranged between O1- and O2-like compositions.

Therefore it is probable that Mathews, or at least Crucible, developed both of the major types O1 and O2 though O2 came later.

He preferred the O1-type composition, particularly when it had the vanadium addition for grain pinning. Gill liked vanadium additions in general and he worked for the Vanadium Alloys Steel Company. The resistance to cracking and the lower sensitivity to hardening temperature of the O1 composition may have been what led to the modification from the original O2.

O1 gets its oil hardening properties from the combination of Mn and Cr, both elements that contribute to hardenability. The tungsten also helps with fine grain and wear resistance though the amount is small enough that its contribution to those properties is relatively small. The main benefit of O1 compared with simple carbon steel like is that it can be hardened in oil and better avoid cracking, distortion, and size changes. Tool and Die companies were very excited about Ketos steel, such as found in a report in American Machinist by C.

Heiby and George Coles of the H. Mueller Manufacturing Company [10]. Because O1 became a very popular tool steel, it is relatively difficult to determine who used it in knives first. It has been popular with both forging bladesmiths and stock removal knifemakers due to its wide availability in a range of sizes, and ease in forging and heat treating. One knifemaker known for his use of O1 was W.

I contacted Randall Made Knives and they confirmed to me that their understanding is that the steel used did not change. An article on Randall knives by Jim Williamson identifies the steel as being produced by Uddeholm [14]. Uddeholm sold a version of O1 under the name UHB at that time [15].

So while it is hard to say that Randall was the first to use O1 he was an influential user of it in the very early period of American-made custom knives. I am not sure why he used Uddeholm steel. Perhaps it was available in a better size, cost, or he felt the steel was higher quality. Below I have a micrograph of O1 that I took.

You can compare it against other knife steels by reading this article. The carbides are relatively small and well distributed. Fine carbides generally mean good toughness and edge stability. A cold treatment can be added after the quench for a small increase in hardness as well as a corresponding decrease in toughness not tested here.

Despite the fine carbide structure of O1, its toughness is not particularly high when compared with other steels. For example, A2 is probably the closest counterpart to O1 in terms of use in die steels but is air hardening instead of oil hardening. However, A2 has both better toughness and wear resistance than O1, despite the fine carbide structure of O1. The relatively poor toughness of O1 seems to be a consistent finding whether in toughness testing of Knife Steel Nerds, Crucible, or Carpenter.

Here is a comparison between Knife Steel Nerds and Crucible toughness numbers showing that they correlate very well and that the results for O1 are also similar note the scales are different due to different sample geometries :. O1 is not known for high wear resistance, it has significantly lower abrasion resistance than D2, for example [17]. And generic ratings from steel manufacturers typically show O1 having lower wear resistance than the majority of their other die steels.

O1 was tested at a very high hardness 64 Rc but its edge retention was clearly lower than the other steels:. This is easy to understand through knowledge of the effects of carbides on edge retention which you can read about here. Low alloy steels in general , , O1, W2, etc. The biggest benefit of O1 over the years has been its availability nearly everywhere and relatively low cost. It is also relatively easy to heat treat due to its austenitizing requriements being similar to other low alloy steels with the benefit of being easy to quench for full hardness, even with slow oil because of its high hardenability.

The downside is it is more difficult to anneal due to its high hardenability. Learn about annealing here: Part 1 and Part 2. O1 is also easy to finish and sharpen because of its low wear resistance.

The forgeability of O1 is also very good. Halcomb Steel was purchased by Crucible only a few years later but continued to sell the steel as Halcomb Ketos for many years, and Crucible continues to sell O1 as Ketos steel.

Oil hardening steel was very popular with tool and die companies due to the very small amount of warping, distortion, and size changes the steel would see due to oil hardening. The other major tool steel companies made their own oil hardening steels which were all versions of O1 and O2. O1 has a fine microstructure of cementite.

Its edge retention is relatively low due to the small amount of soft iron carbides cementite. O1 has been common in knives for decades. Famously O1 has been used by Randall Knives starting in or so and continuing to today. I haven't tried this so can't comment as to their effectiveness. The anti-scale not only makes your life easier in removing the scale, it is also meant to prevent carbon migration from the steel. Steel box section or pipe. This is to equalise as well as lower the temperature in the forge.

I welded one up. Some scrap to put on the box to help regulate and lower the temp. Thermocouple thermometer to accurately measure the temperature in your forge.

Method of correcting any warps. I use a vice and also a big chunk of straight steel that I clamp the knife to when tempering. Trace the design onto steel of suitable thickness mine is 2mm thick, this is thin but appropriate for the knife my wife wanted. Drill the holes for the handle pins. If you leave this until after hardening you and your drill bits will regret it. Coat the blank in anti-scale. You can dip it or paint it on. Make sure you have a good coating.

The first coat may have trouble sticking, but subsequent coats should go on okay. You can use a hairdryer to dry it between coats. Make adjustments until you can hold the temp between c. Put the large heated scrap steel mine is one inch square bar in the quench oil and take the temp. Once you are happy you can achieve the temperatures, put your oven on at c, ready for the tempering.

The scrap steel is hot and ready to heat the oil. The blank is coated with anti scale. Your oven is on. Your method of correcting warps is to hand.

Put the blank in the tube. Being thin steel it will heat quickly. It will be non magnetic, but trust your thermocouple more than this. The hardness of the handle is not important, so if some of the blank won't heat up properly make sure this is the handle part. You can see in the photo that the blade part is red, the tang of the handle isn't. This is the best I can do with my kit and is good enough.

Keep it there for at least 10 minutes this is called 'soaking'. Meanwhile bring your oil up to temp. Oil holds heat pretty well. When your 10 mins are up get your tongs and immediately plunge it into the oil. Hopefully you will have the fun and drama of flames. This is my favourite part of knife making. I usually hold it in the quench for about 20 seconds. It needs to cool, but not so much that you can't straighten any warps.

If the blade is warped act quickly and straighten it while it is still hot. One of my three knifes had a warp, so I immediately straightened it in the vice and clamped it to some heavy steel. File test it to make sure it has hardened.

The file should skate and not bite. If it hasn't hardened you need to repeat. Get it straight into the oven and temper it for 2 hours. If you are using clamps in the oven make sure yours doesn't have a plastic quick release button or it will melt like mine has.

It just now needs sanding, polishing, sharpening and the handle to be glued and pinned on and sanded to shape. By LaurenceB23 Follow. More by the author:. In short: Coat the knife with anti-scale ATP in my case.