jPrichard10 

Hi all,

I'm curious what the metallurgical differences of NiCrMo and CrMo translate to in terms of frame building. Is 8630 stiffer? Stronger? More corrosion resistant? Different brazing temperatures? Kaisei draws both steels to the same wall thicknesses, so I'm wondering what this translates to on the bike/in the jig.

https://www.bikeschool.com/PDF_Files/KAISEIPoster.pdf

Andrew R Stewart 

I can't speak to the specifics of either material but here's some well agreed on generalizations.

Pretty much all steels have the same Young's Modulus (stiffness). Some stainless can vary from this but not by much. Steels used on a bicycle are a balance between strength and brittleness. Too much strength and the steel tends to have too little elongation. Elongation is a needed quality to a structure which sees many (hundreds of thousands) of cycles of stress/flexing and not fail. Corrosion resistance- coating with paint and periodic maintenance do a pretty good job already. Brazing temps- here there is a change which will effect the builder. What type of joining techniques are available to the builder and how these choices requires the builder to use certain joint set up methods is a real factor.

An example of this is well known with 753 Reynolds tubing which wasn't meant to be bronze brazed (due to the temp level changing the heat treatment). So to join tab type drop outs to stays/blades with silver a plug or some insert was needed to reduce the gaps to a size silver could work with.

Another example of a tube's having a lot of strength is the maintaining alignment during the brazing process. Heat distorts the frame members as we all know. The builder must take into consideration how much and where this distortion happens and set up the tubing to accommodate this as well as use a building sequence which minimizes this. After a frame is completed a too strong steel won't be able to be cold set. Aermet tubing had this issue.

I'll be interested in reading more from better informed posters. Andy.

Scooper

As Andy says, all steels from AISI 1010 plain carbon steel to the latest and greatest high strength stainless alloys like Carpenter Custom 455 (Reynolds 953) have virtually the same "stiffness" with an Elastic (Young's) Modulus of ~200 GPa.

AISI 4130 chromoly has a minimum ultimate tensile strength (UTS) of 560 MPa, while AISI 8630 has a minimum UTS of 620 MPa, so 8630 is a slightly stronger alloy, but these numbers can vary depending on heat treatment.

I can't answer your questions about corrosion resistance and brazing temperatures, but my assumption is that they would be very similar.

pwyg

As told by one of my predecessors who was taught to build by a Phd metallurgist said the steel alloy did not mean much in the overall strength, but said it was all in the heat treatment. The only way to preserve the heat treatment was to keep the joining temp. under 1350 degrees. As for the best range for strength, I had a long talk with Lon at Nova he told me about some independent testing they had done and the tubing that faired the best was in the 175,000 range.

jPrichard10 

Thanks all. I guess it doesn't matter since UBI doesn't carry Kaisei tubes any more. Anyone know where I can get them now?

Scooper

The Kaisei tubing plant is located in Fukushima which is only 80 km from Sendai, the epicenter of the earthquake that devastated much of Fukushima Prefecture in 2011.

Our thoughts are with the workers of Kaisei and all of Japan | UBI Blog

I don't have any additional information, but suspect production of Kaisei tubing may have been impacted by the quake and tsunami.

jPrichard10 

Yeah, I wondered about that. I know Nitto is nearby as well; Jan Heine's article from BQ makes it sound like they are faring well. Compass also started crying the Kaisei fork blades some time after the quake, so I figured they were recovering well.

Part of my interest in Kaisei (aside from excellent reports about their tubing) is in supporting those manufacturers hit hard in 2011.

cjroot2004

Hello!

I just had an extensive e-mail conversation with Japan about this. The folks at Kalavinka can ship Kaisei to the USA. The contact info is as follows:

Akio Tanabe

Kalavinka Cycles (Tsukoma Cycle Sports)

* Kalavinka * Tsukumo Cycle Sports

wkh0328@mb.infoweb.ne.jp

https://www.flickr.com/photos/sashae...7602637693990/

They could not quote prices or shipping/handling, but they did say that they offered the full selection of what you see online,


C R

KPacenti

The materials are quite similar.

https://www.makeitfrom.com/compare/C...Ni-Cr-Mo-Steel

duanedr 

It's an old thread but that's a great site for comparing materials! I recently had a question about 316 vs 304 vs 4130 suitability for rack and could have used this. Thanks!