[Snakeoil]

Today I dropped off my shattered center stand with my friend the welder. Some of you may remember my boneheaded experience of heating my '66 centerstand and quenching to restore hardness after straightening it out. The left leg broke off when I tried to put the bike up on it. Broke like glass. Should have tempered the metal. Never thought there it was that high a grade of steel.

When I dropped it off, my friend was rather amazed at what he saw. He's second generation in the biz and in his early 50's. Does nothing but weld and straighten metal for a living. Truck chassis are his specialty. When I told him about heating it with an oxy-acetylene tourch he said that was a mistake. Said that there is a lot of carbon imparted into the steel when you use acetylene. Said you need to use oxy-propane for that kind of work.

I never would have considered that point. Thought I'd pass it along.
regards,
Rob

 

[terdah2]

Today I dropped off my shattered center stand with my friend the welder. Some of you may remember my boneheaded experience of heating my '66 centerstand and quenching to restore hardness after straightening it out. The left leg broke off when I tried to put the bike up on it. Broke like glass. Should have tempered the metal. Never thought there it was that high a grade of steel.

When I dropped it off, my friend was rather amazed at what he saw. He's second generation in the biz and in his early 50's. Does nothing but weld and straighten metal for a living. Truck chassis are his specialty. When I told him about heating it with an oxy-acetylene tourch he said that was a mistake. Said that there is a lot of carbon imparted into the steel when you use acetylene. Said you need to use oxy-propane for that kind of work.

I never would have considered that point. Thought I'd pass it along.
regards,
Rob

When You have welded a part like this, it is a good advice to use a large acytelen/oxygen welder and heat the part to red and let it cool slowly. (What You use to heat it with is not so important) This will take ut the tension and hard areas in the metal. Never cool in water! When You do this You will get cracks at once, and it will crack like glass. Allways do this after welding when You dont know what steel You are dealing with! The carbon from a to rich acetylene tourch will onely give You a hard surface of some 1/1000mm and this is not dangerous as long as You have a normal core.

 

[Snakeoil]

Your suggestion is what I've always thought to be the proper process. Heating to red and allowing to slowly cool is supposed to maintain the original properties and remove any residual stresses from the metal. What I found after straightening and welding my sidestand was it had gone soft. So I decided to harden it by heating and quenching. I think it would have been fine if I had gone back and tempered it after hardening it.

What probably happened the first time around was my repeated heating and straighten make have resulted inadavertently softening the metal. I was letting it air cool each time, but it was kinda cold out so it may have chilled must faster than it should have.

Your comments about the carbon infusing into the metal makes good sense to me. I was suspect about what my friend the welder told me, but was willing to bow to experience in his case. I know there is more carbon in Acetylene that there is in Propane so I thought that might be a contributor. Carbon to Hydrogen ration is 1:1 in Acetylene and about 3:8 in Propane. But I believe if you have a neutral flame, you are not leaving any carbon behind in the steel. It all becomes CO2.
Thanks for the input. I'm not sure we'll be able to save this stand.
regards,
Rob

 

[panda]

I just wonder if maybe you straightened it when it was just not quite hot enough, thereby work hardening the steel ??