This past week I did a quiz on my site to get a feel for the level of knowledge of my readership (or at least the ones that take quizzes) and of course for fun: Take the Quiz Here.

At the time of writing there are more than 900 responses to the quiz (update: 1000!), which I think is a success. I have performed some analysis of the results of the quiz and so I will go over some of the questions that tripped people up and how I might adjust what I write about on this site based on the responses.

Question 1: Which company developed S30V?

I included this question because it would be relatively easy for knife fans that know about a few steels but don’t necessarily know much about metallurgy. For a metallurgist that doesn’t know knife steels, however, they probably wouldn’t know the answer to this one. With 73% of people getting it right, most of the readers of my website know about individual knife steels.

Question 2: What steel phase are knife steels primarily made up of?

I got a few complaints about this question that they didn’t know if I was referring to the microstructure of a finished knife or the steel as-delivered prior to working with it. I would argue that it is not a “knife steel” until it has been made into a knife, but I understand that the question could be worded more clearly. Knives are generally heat treated to have high hardness which requires a martensitic microstructure. When delivered to a knifemaker the steel is soft for easy machining and is made up of a ferrite-carbide or pearlite microstructure. Sorbite is an outdated term that refers to heavily tempered martensite.

Question 3: At what hardness range is the steel in a typical knife?

Most people knew the answer to this question, which indicates that hardness values for knives are relatively well known. Or that this is a question that is easy to Google. The Rockwell C hardness is often advertised for knives, but more often with higher end knives rather than the run of the mill Walmart purchase.

Question 4: What is an air hardening steel?

Historically to form a hard martensitic microstructure a steel must be heated to high temperature and then quenched in water or oil. When enough manganese, chromium, nickel, molybdenum, etc. is added the steel can be cooled much more slowly, and when enough of those elements are added the steel will harden even when cooling in air. These steels are called “air hardening.” My alternative nitriding answer was convincing to some of the people that took the quiz, but most were not tricked into believing that steel itself can divide diatomic oxygen.

Question 5: What turns iron into steel?

The difference between iron and steel is the addition of a single element: carbon. Even this is perhaps an oversimplification as there are ultra low carbon steels, or steels that are hardened with other elements like nitrogen, but the textbook definition works best for a quiz like this. Rapid cooling, martensite, forging, etc. are not required by definition for iron to be steel.

Question 6: What makes steel stainless?

When sufficient chromium is added to steel, an extremely thin layer of chromium oxide is formed which protects from corrosion. Most people knew the answer to this one.

Question 7: What is secondary hardening?

Secondary hardening is the use of high tempering temperatures with certain types of steels, usually alloyed with high amounts of molybdenum and tungsten. At the high tempering temperatures very fine molybdenum or tungsten carbides are formed which harden the steel. Only 47% of people got this question right. Heating and quenching a second time was a relatively convincing alternative answer, while a few jokesters thought that secondary hardening really is an 80’s hair metal band.

Question 8: What is kinetics?

The most difficult part of writing this question was trying to figure out whether I should use the singular “is” or the plural “are” for kinetics, but I think I got it. This was another difficult question for many of the quiz takers. Kinetics is not a word often used by those writing about metallurgy for knifemakers or for knife enthusiasts. It is a relatively common term in science, however, also used in chemistry. This is confirmed by the fact that those who reported that they “like science” got this question right 67% of the time, while knifemakers and those that “like knives” both got it right 57% of the time.

Question 9: What is tempering?

I also got a few complaints about this one, since tempering of steel does not reduce its hardness in all cases, such as with secondary hardening. However, I checked a few textbook definitions of tempering while writing this question and all referred to softening of steel so I went with the simple definition. Sometimes the entire heat treating process is mistakenly referred to as “tempering” even though tempering is only one step of the process.

Question 10: Why are you interested in steel?

Unfortunately the results page generated by the quiz plugin I used only reported one of the correct answers for this and the final question even though all were correct except for “I’m not interested in steel.” The scoring was correct but some thought that they “missed” the question and missed out on one of their points toward being a real life “steel nerd.” Only one response was incorrect, however; after all, any reason for being interested in steel makes you a steel nerd. This question gave me some info about the people reading the website, and some understanding of what the different groups want from the website. I probably write to knifemakers primarily so I was somewhat surprised that so many knife “fans” responded to the quiz. That may change slightly the selection of writing topics in the future. Fortunately not very many people took the quiz that are not interested in steel.

Question 11: What would you like to learn about steel?

“Comparisons between different steels” was the winner for this category, with general metallurgy not too far behind. History was the loser here, even behind “I’m not interested in learning about steel.” That’s too bad because I’m still going to write some articles about the development of different steels and processing techniques. There were clear differences between the preferences of different groups, however, as knifemakers answered “How to best heat treat steel” 40% of the time, perhaps because they would like to improve their knives. Those that “like knives” answered “Comparisons between different steels” 37% of the time, I would guess because they want more information about what steel to look for in a knife. Those that “like science” answered “General metallurgy” 34% of the time, indicating that they like to learn about general science topics. And those that are “not interested in steel” answered “I’m not interested in learning about steel” 64% of the time, which is probably expected.

Final Scores

Overall scores were good, with a slim majority being classified as “steel nerds” according to the scoring system, and most of the rest being “almost nerds.” This is in part due to the steel knowledge of the people taking the quiz and in part due to the questions being relatively easy. The average score was 8.6, the minimum score was 2 and the standard deviation was 1.8. Knifemakers had the highest average score with 9.4, those that “like science” edged out those that “like knives” with scores of 8.7 vs 8.4. I am sure there is some overlap between the groups but the quiz only allowed one response. The worst scores were from those that were “not interested” in steel with an average score of 6.2.

Conclusions

Doing the quiz was a great success and very fun. Let me know in the comments if you think I should do more quizzes and what you would like the quiz to be about. Do you want a more difficult quiz? Do you want quizzes on specific steel-related topics?

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