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What will happen when you quench steel in liquid nitrogen is that the LN2 will immediately turn to vapor and you will get a very persistent vapor phase - it is a very slow quench. Only vigerous agitation will break up the vapor phase. Another thing to concern yourself with is that all the LN2 will also turn to gas and create a suffocation hazard. This was well documented about 30 years ago when several people died when a manufacturer tried it.

Canola will get faster if there is water present. It will not separate as canola or vegetable oil is hydrophillic (likes water). Oil that contains more than 1000 ppm of water can be a serious fire hazard as the water turns to steam and pushes the oil out. Often the oil ignites from the hot part. Then you have a real mess with flaming oil over everything

Why not nitride the blade edge of the stainless?

Wind turbines are really a favorite of mine. They have to be forged, machined, heat treated and then assembled. Good solid manufacturing work. It is really cool when they are quenched and knowing that you had a part in it when you see them erected.

Download Timken Practical Guide for Metallurgists - lots of good data there and free. There is a new edition out there - just go to the Timken site and download it. Timken Practical Data for Metallurgist.pdf

No - you are not missing anything. I misread it - I was thinking that you had a laminate of low carbon steel with a high carbon steel. I goofed. Thank you for calling it to my attention. The Ms temperature that you determined empirically is about right. Because the section size is small and the thermal mass of the salt is high, I would use a much shorter time at the martempering temperature.

That certainly makes sense. What you could have also done is created bainite in the 1070 - making it nicely tough, but still had martensite in the lower hardenability stuff. For grins - try a 1070 blade with only 1070 and austemper it, i.e., hold at Bs (°F) ~ 1526 - 486 x C - 162 x Mn - 126 x Cr - 67 x Ni - 149 x Mo for a period of time - then quench. You will end up with a baiitic structure - hard and tough. Maybe not real hard - maybe 53+ HRC but it will be real tough.

Ms temperature for 1065 is 525 and Ms for 1090 is 420F - so what you found empirically is about right. I have not found the Ms temperature for 15n20 but it is very high - much higher than 525F. I found the data on p 79 of "Practical Guide for Metallurgists" - very practical little booklet that is a freebie. As an approximation: Ms (°F) ~ 930 - 600 x C - 60 x Mn - 20 x Si - 50 x Cr - 30 x Ni - 20 x Mo - 20 x W from E. S. Rowland and S. R. Lyle, Trans. ASM, 37, 1946, p 27. I agree that you probably have a slight decarb.

There is always a "pucker" factor - Hopefully whenever I do a fill like that I have looked at all the mitigating factors like quench rate, part alloy, thickness, agitation, quenchant used - and how to control the concentration (if polymer). Luckily I have only had one failure and that was because of agitation issues. I thought it was stronger than it was - after we corrected it, it worked like a champ. Regardless of what you are doing - there is always a risk - that is why they pay me the big bucks - to minimize risk to the company; the customer, and to the part. One I get to the actual load - it is more of excitement and celebration than anything else. BTW, I am trying to put together some additional pictures. But to give you an idea of the size of the wind turbines - here are some small blades for 1.5MW turbines: Now each of these blades has a yaw and pitch bearing - that means numerous parts from rolled rings that bust be heat treated (typically either 52100 or carburized 9310). The rings, races and bearings (the balls) must be heat treated.

Thank you - I appreciate it. BTW, I am not a chemist but a simple metallurgist. I have chemist's for lunch.

Just call our customer service at 610-666-4000 (ask for customer service).

I would say that it would behave in a very similar manner

Depends on what you want (see - you can never get a straight answer from a metallurgist ) If you are looking to get the O1/O2 hard I would suggest using Houghto-Quench 100. The steel that you just cited has a very high hardenability because of the Cr and V. The V and W (Tungsten) will make nice carbides and help retain a nice edge. However, if you ever want to do lower hardenability alloys you will have a problem getting the lower hardenability parts hard. You may want to consider Houghto-Quench G - this is a medium speed oil that will get the high hardenability parts hard and should get your low hardenability parts hard too.

I wouldn't use diesel fuel - the flash point is way too low. I also wouldnt use motor oil either because of the additives and stuff that is in the oil for lubrication. A straight mineral with low viscosity will get you the speed you want a lot safer.

An 11-sec quench oil refers to the GM Quenchometer test. It is a pretty cool test - essentially it measures the time it takes to cool a nickel ball that is 0.5 inches in diameter, from 1600F to the curie point. There is a lot of variability in the test, but it has been used in the US for years it is hard moving people to a better test like a cooling curve. This would compare directly to Houghto-Quench G. And yes I do know