Re: frame sheared :(

[jtaylor]

"Paul - ***" <[email protected]> wrote in message
news:[email protected]...
> Matthew Vernon came up with the following;:
>
> > Is a repair likely to be a good solution, or does the fact that one
> > bit of the frame's failed mean the rest may give up in short order?
>
> That's the bit that'd worry me, especially in the areas that took the
strain
> when the down tube fractured. A decent frame specialist would advise on
> this likelihood though.
>
> I get the impression from the picture that this wasn't a sudden fracture,
> there appears to be rust down part of the crack, did you get any warning
> this was happening? If it was a steady deterioration and you kept riding,
> I'd have to think about the extra loads and flexing that the weakness
> created in the rest of the frame. I'm not sure I could absolutely trust
it
> again.
>

[ note r.b.t. added to newsgroup header ]

This is a classic heat-affected-zone fracture.

Good frame building technique can reduce the likelyhood of this happening
again, in the joints that are repaired - but other original joints may well
have a greater than acceptable chance of the same fracture. You should
consider these factors:

a) a new frame may have the same problem, especially if it is the same or
similar model from the same manufacturer
b) steel frames, such as yours, fail in graceful rather than catastrophic
modes in the main; and if you check every now and then you will see any
other before they are an immediate danger.

 

[mb]

In article <%[email protected]>,
[email protected] says...
>
> "Paul - ***" <[email protected]> wrote in message
> news:[email protected]...
> > Matthew Vernon came up with the following;:
> >
> > > Is a repair likely to be a good solution, or does the fact that one
> > > bit of the frame's failed mean the rest may give up in short order?
> >
> > That's the bit that'd worry me, especially in the areas that took the
> strain
> > when the down tube fractured. A decent frame specialist would advise on
> > this likelihood though.
> >
> > I get the impression from the picture that this wasn't a sudden fracture,
> > there appears to be rust down part of the crack, did you get any warning
> > this was happening? If it was a steady deterioration and you kept riding,
> > I'd have to think about the extra loads and flexing that the weakness
> > created in the rest of the frame. I'm not sure I could absolutely trust
> it
> > again.
> >
>
> [ note r.b.t. added to newsgroup header ]
>
> This is a classic heat-affected-zone fracture.
>

Er, no.
I wouldn't have thought a brazed frame would have much in the way of
heat affected zones. HAZ usually refers to a welded joint.

It looks like it started at the stress raiser on the underside of the
tube, where the lug meets the tube.

[snip]

--
Mike

 

[Simon Brooke]

in message <%[email protected]>, jtaylor
('[email protected]') wrote:

>
> "Paul - ***" <[email protected]> wrote in message
> news:[email protected]...
>> Matthew Vernon came up with the following;:
>>
>> > Is a repair likely to be a good solution, or does the fact that one
>> > bit of the frame's failed mean the rest may give up in short order?
>>
>> That's the bit that'd worry me, especially in the areas that took the
> strain
>> when the down tube fractured. A decent frame specialist would advise
>> on this likelihood though.
>
> [ note r.b.t. added to newsgroup header ]
>
> This is a classic heat-affected-zone fracture.
>
> Good frame building technique can reduce the likelyhood of this
> happening again, in the joints that are repaired - but other original
> joints may well
> have a greater than acceptable chance of the same fracture. You
> should consider these factors:
>
> a) a new frame may have the same problem, especially if it is the same
> or similar model from the same manufacturer

It won't be, those frames haven't been made for at least fifteen years
and Raleigh no longer make any frames.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

 

[James Thomson]

"Simon Brooke" <[email protected]> wrote:

[snip]

> those frames haven't been made for at least fifteen years

[snip]

Those frames were still made in 2000, prior to the closure of Raleigh
Special Products. Mine, bought in 2000, was built in '98 or '99.

James Thomson

 

[jtaylor]

"mb" <[email protected]> wrote in message
news:[email protected]...
> >
> > This is a classic heat-affected-zone fracture.
> >
>
> Er, no.
> I wouldn't have thought a brazed frame would have much in the way of
> heat affected zones. HAZ usually refers to a welded joint.
>

Think again.

Brazing is hot enough (850 centigrade or more) to anneal steel. There _is_
a heat-affected-zone.

Some (the most common) methods of brazing generate a _larger_ HAZ than some
forms of welding.

 

[mb]

In article <[email protected]>,
[email protected] says...
>
> "mb" <[email protected]> wrote in message
> news:[email protected]...
> > >
> > > This is a classic heat-affected-zone fracture.
> > >
> >
> > Er, no.
> > I wouldn't have thought a brazed frame would have much in the way of
> > heat affected zones. HAZ usually refers to a welded joint.
> >
>
> Think again.
>
> Brazing is hot enough (850 centigrade or more) to anneal steel. There _is_
> a heat-affected-zone.

What on earth is your definition of "anneal"?
Yes, there is a heat affected zone of sorts, but not one which has
significant changes in grain structure. Not enough to cause "classic
heat affected zone cracking".

>
> Some (the most common) methods of brazing generate a _larger_ HAZ than some
> forms of welding.
>

You don't know what a heat affected zone is, do you?

--
Mike

 

[jtaylor]

"mb" <[email protected]> wrote in message
news:[email protected]...
> In article <[email protected]>,
> [email protected] says...
> >
> > "mb" <[email protected]> wrote in message
> > news:[email protected]...
> > > >
> > > > This is a classic heat-affected-zone fracture.
> > > >
> > >
> > > Er, no.
> > > I wouldn't have thought a brazed frame would have much in the way of
> > > heat affected zones. HAZ usually refers to a welded joint.
> > >
> >
> > Think again.
> >
> > Brazing is hot enough (850 centigrade or more) to anneal steel. There
_is_
> > a heat-affected-zone.
>
> What on earth is your definition of "anneal"?

50 degrees above the Austentic temperature. For the range of carbon steel
commonly used in bicycle manufacture, that's around 800 centigrade - and the
850 I quoted above is on the low range for brazing temps.

> Yes, there is a heat affected zone of sorts, but not one which has
> significant changes in grain structure. Not enough to cause "classic
> heat affected zone cracking".
>
> >
> > Some (the most common) methods of brazing generate a _larger_ HAZ than
some
> > forms of welding.
> >
>
> You don't know what a heat affected zone is, do you?

Think again (again...)

 

[mb]

In article <[email protected]>,
[email protected] says...
>
> "mb" <[email protected]> wrote in message
> news:[email protected]...
8<
> >
> > What on earth is your definition of "anneal"?
>
> 50 degrees above the Austentic temperature.


"Austentic"?
Austenite? Austenitic? What has this to do with heat affected zone
cracking?

Annealing = heating then cooling slowly.
This would improve the mechanical properties of the steel and help
prevent HAZ cracking.


> For the range of carbon steel
> commonly used in bicycle manufacture, that's around 800 centigrade - and the
> 850 I quoted above is on the low range for brazing temps.
>
> > Yes, there is a heat affected zone of sorts, but not one which has
> > significant changes in grain structure. Not enough to cause "classic
> > heat affected zone cracking".
> >
> > >
> > > Some (the most common) methods of brazing generate a _larger_ HAZ than
> > > some forms of welding.
> > >
> >
> > You don't know what a heat affected zone is, do you?
>
> Think again (again...)
>

Whatever you think it is, you're not going to get "classic heat affected
zone" cracking.
And that sheared frame wasn't caused by it.

--
Mike

 

[Simon Brooke]

in message <[email protected]>, mb
('[email protected]') wrote:

> In article <[email protected]>,
> [email protected] says...
>>
>> "mb" <[email protected]> wrote in message
>> news:[email protected]...
>> > You don't know what a heat affected zone is, do you?
>>
>> Think again (again...)
>
> Whatever you think it is, you're not going to get "classic heat
> affected zone" cracking.
> And that sheared frame wasn't caused by it.

Guys, heat and light, please. I don't know which of you is right but
just saying 'tis/'tisn't doesn't get anywhere and doesn't inform those
of us who don't understand about these things at all. If you're going
to carry on this sort of argument on a public forum please can you
explain in clear terms why (each of) you think what you do.

--
[email protected] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; killing [afghan|iraqi] civilians is not 'justice'

 

[mb]

In article <[email protected]>,
[email protected] says...
> in message <[email protected]>, mb
> ('[email protected]') wrote:
>
> > In article <[email protected]>,
> > [email protected] says...
> >>
> >> "mb" <[email protected]> wrote in message
> >> news:[email protected]...
> >> > You don't know what a heat affected zone is, do you?
> >>
> >> Think again (again...)
> >
> > Whatever you think it is, you're not going to get "classic heat
> > affected zone" cracking.
> > And that sheared frame wasn't caused by it.
>
> Guys, heat and light, please. I don't know which of you is right but
> just saying 'tis/'tisn't doesn't get anywhere and doesn't inform those
> of us who don't understand about these things at all. If you're going
> to carry on this sort of argument on a public forum please can you
> explain in clear terms why (each of) you think what you do.
>
>

It's a bit irritating to try and argue with a guy who can only say
"think again (again)", etc. It makes him look like a fool.

Heat affected zone (HAZ) cracking only occurs with fusion welding
processes and can be caused by;
1. Hydrogen. Hydrogen comes from the "consumable", the filler material
and/or it's flux. The hydrogen doesn't form any compounds in the weld
and sits there all by itself and can cause cracking by escaping from the
HAZ.
Prevented by using low hydrogen electrodes and/or use of preheat before
welding.
2. Excessive hardness in the HAZ. Usually only with high carbon steels,
again prevented by using low hydrogen electrodes and preheat. Controlled
cooling will also help (cover with heatproof blanket, bury in sand,
etc).

A crack in a brazed joint would probably be caused by;
1. Fatigue. Probably starting at some sort of stress raiser, like the
change in section where the lug meets the tube, as I stated a long time
ago.
2. Base metal erosion. Caused by the filler forming an alloy with the
base metal and dissolving the base metal.

TWI (The Welding Institute) don't mention any HAZ cracking when talking
about likely defects in brazing. I wonder why...

--
Mike

 

[[email protected]]

Dear JT & list:

I build frames, quite a few of them actually. I see quite a few
failures, too, though not of the frames I build. I tracked down the
failure photo on the UK bicycle list where it was originally posted.
It looks like a classic shear failure - I've seen that on high-end TIG
welded steel frames as well, and even frames that were well-made but
were ridden beyond the limits of their design.

The bike looks well-used. Perhaps the rider (Matthew) is on the heavy
side and rides cobbles a lot? Even so, a well-made lugged road frame
should have lasted him 20 years or more.

The shearing started at a lug point and took some time to develop.
What may have happened is the joint was overheated. This is usually
not a problem in a silver-brazed frame, but it does happen with bronze
brazing, especially in a mass-production setting. Chrome moly is
especially vulnerable. You cook a joint and the bronze invades the
crystal structure of the steel. Typically you'll hear a sizzle, there
will be a puff of greenish smoke, now you've done it. When you clean
up the joint the steel will often show a few cracks, filled with tiny
lines of bronze. The right thing to do is toss the frame, or at least
clean out the bad tube completely from its lugs and put in a new one.

In this case, a localized area that got cooked, like a lug point, could
have been the starting point for this failure, which, once started then
progressed. It would be good to actually inspect the frame, but it
looks to me like Raleigh should do the right thing.

There are scores of frame builders in the US and abroad who could build
a frame that would make Matthew (the original owner) forget all about
the Raleigh. You could troll the list:
[email protected]
The dollar is weak, good time to order.

good luck

jn

AKA "Thursday"

 

[Matthew Vernon]

[email protected] writes:

> The bike looks well-used. Perhaps the rider (Matthew) is on the heavy
> side and rides cobbles a lot? Even so, a well-made lugged road frame
> should have lasted him 20 years or more.

I wouldn't consider myself on the heavy side, no, and nor was the only
previous owner (who is a friend of mine). I do ride over cobbles
occasionally, but not all that much.

> There are scores of frame builders in the US and abroad who could build
> a frame that would make Matthew (the original owner) forget all about
> the Raleigh. You could troll the list:
> [email protected]
> The dollar is weak, good time to order.

Maybe so, but am I really likely to get a better frame than my
(up-to-now) trusty Raleigh for less than the cost of getting a repair
in the UK (about 300UKP plus strip+rebuild cost)?

Thanks,

Matthew

--
`O'-----0 `O'---. `O'---. `O'---.
\___| | \___|0-/ \___|/ \___|
| | /\ | | \ | |\ | |
The Dangers of modern veterinary life

 

[Dan]

"jtaylor" <[email protected]> wrote in message
news:%[email protected]...
>
> "Paul - ***" <[email protected]> wrote in message
> news:[email protected]...
> > Matthew Vernon came up with the following;:
> >
> > > Is a repair likely to be a good solution, or does the fact that one
> > > bit of the frame's failed mean the rest may give up in short order?
> >
> > That's the bit that'd worry me, especially in the areas that took the
> strain
> > when the down tube fractured. A decent frame specialist would advise on
> > this likelihood though.
> >
> > I get the impression from the picture that this wasn't a sudden
fracture,
> > there appears to be rust down part of the crack, did you get any warning
> > this was happening? If it was a steady deterioration and you kept
riding,
> > I'd have to think about the extra loads and flexing that the weakness
> > created in the rest of the frame. I'm not sure I could absolutely trust
> it
> > again.
> >
>
> [ note r.b.t. added to newsgroup header ]
>
> This is a classic heat-affected-zone fracture.
>
> Good frame building technique can reduce the likelyhood of this happening
> again, in the joints that are repaired - but other original joints may
well
> have a greater than acceptable chance of the same fracture. You should
> consider these factors:
>
> a) a new frame may have the same problem, especially if it is the same or
> similar model from the same manufacturer
> b) steel frames, such as yours, fail in graceful rather than catastrophic
> modes in the main; and if you check every now and then you will see any
> other before they are an immediate danger.
>
>

The photo is here:
http://www.pick.ucam.org/ucgi/~matthew/gallery/misc/misc?display=mcvbike.jpg
The photo shows a crack that is rusty (old) at the bottom and shiny (new) at
the top. It seems to have propagated from the tip of lug on the bottom side
of the down tube. There is also a dent and a rusty scrape where the brake
caliper has hit the down tube. It looks like the bike has been in a crash at
some time in the past. This may be the origin of the initial crack.