S35VN Properties and How to Heat Treat

[Larrin]

New article about S35VN looking at its design, edge retention, toughness, corrosion resistance, etc. And a series of experiments on heat treating it including final hardness and toughness. https://knifesteelnerds.com/2020/01/13/s35vn-steel-properties-and-how-to-heat-treat/

 

[Willie71]

Thanks! I always used to heat treat s35vn to Rc60/61, as the advice at that time suggested it would get too chippy higher than that. This is why testing is so important. I have two bars of thin s35vn left, 0.060”, for kitchen knives. I will be using 2025f, and tempering to Rc63. This should improve the fine edge stability with the higher hardness, my only real complaint with this steel. Is the carbide refinement in z-wear/cru-wear/V4e similar, causing the same flat toughness/hardness distribution?

Larrin, based on your testing, is s45vn a better or worse choice for fine slicing knives?

 

[Larrin]

Is the carbide refinement in z-wear/cru-wear/V4e similar, causing the same flat toughness/hardness distribution?

Almost all of the heat treatments used with Z-Wear were 1950°F austenitize so I don't think the flat behavior can be ascribed to the same behavior. The lower hardness values tested with Z-Wear were from the 1000°F temper which were found to be lower in toughness for a given hardness. That led to the flat behavior. With V4E we also have a relatively flat line but the line is connecting one value at 64 Rc to another at 57 Rc so it's hard to draw many conclusions from that.

Larrin, based on your testing, is s45vn a better or worse choice for fine slicing knives?

That's a good question. The toughness was measured to be higher with S35VN though we did a wider range of heat treatments to try to dial it in. The S45VN was found to have a finer carbide structure which would be expected to improve a fine edge. However, I think there is more safety in relying on actual mechanical tests rather than extrapolating from microstructure so I would probably recommend S35VN unless higher edge retention or corrosion resistance was preferred.

 

[Willie71]

Almost all of the heat treatments used with Z-Wear were 1950°F austenitize so I don't think the flat behavior can be ascribed to the same behavior. The lower hardness values tested with Z-Wear were from the 1000°F temper which were found to be lower in toughness for a given hardness. That led to the flat behavior. With V4E we also have a relatively flat line but the line is connecting one value at 64 Rc to another at 57 Rc so it's hard to draw many conclusions from that.

That's a good question. The toughness was measured to be higher with S35VN though we did a wider range of heat treatments to try to dial it in. The S45VN was found to have a finer carbide structure which would be expected to improve a fine edge. However, I think there is more safety in relying on actual mechanical tests rather than extrapolating from microstructure so I would probably recommend S35VN unless higher edge retention or corrosion resistance was preferred.

Right, z-wear has a few more coupons awaiting grinding. I think I went up to 2050f, iirc. I’d have to double check.

I like s35vn, so no need to bring in another steel yet.