Weld failure on SAE-1045

Date 04-30-2010 21:35

SAE 1045 is a medium carbon steel (carbon content 0.45 %) and can not be welded like low carbon steel (carbon content 0.25 % max.). Preheat is mandatory. If it wasn't done, good chances are that the weld is unsatisfactory.
Giovanni S. Crisi
Sao Paulo - Brazil

By R McLead (**)

Date 05-01-2010 00:18

Giovanni,

My office is in Quality Control at the company’s main manufacturing plant and I suspect that at the manufacturing plant that these components were made the WPS was not followed. I was looking for opinions if this is a typical type of failure when preheat was not performed.

Thanks,
Rey

By MBSims

Date 05-01-2010 02:25

This type of fracture is consistent with fractures I have observed in welded 1045 soil anchors with A36 flutes. However, to confirm underbead cracking, you will need metallographic examination of cross sections of the weld. This should include microhardness traverse at 0.010" spacing across the weld and HAZ to the unaffected base metal. Scanning electron microscopy of the fracture surface is also helpful in differentiating intergranular features of underbead cracking from the dimpled appearance of ductile overload. Locate a good local metallurgical testing lab for these services.

Also, a 1/4" fillet seems a bit small considering the size of the shaft and hub.

By R McLead (**)

Date 05-02-2010 02:33

Thanks for the reply; unfortunately the company does not have what is needed to perform a metallographic examination and the microhardness test. I would have to find someone or a lab to do this and the fillet does seem to be a bit small

Rey

By DaveBoyer (*****)

Date 05-01-2010 02:13

I am not sure what I am looking at in these pictures.

Is that a blind hole in the flange? It LOOKS like a fractured section of the shaft in that hole, and the end of the shaft sort of looks that way too.

Was that shaft a press fit in the hole before welding?

Is that .25" fillet on 1 side of the flange, or both?

How much load is on this part in service?

I would expect a higher pre heat [BOTH PARTS] and possibly post weld heat treatment due to the carbon content of the shaft.

It looks like it ran quite a while after the weld fractured.

By R McLead (**)

Date 05-02-2010 02:51

Dave,
The shaft does have a turned section that is inserted thru the flange, so yes there is welds on the shaft on both sides of flange but it is not a pressed fit. There is a PDF drawing before the photos and I added an exploded view. The total amount of load I do not know, all I can say is it is an idler stub shaft on a conveyor. Also the shaft its self did break on the other side of flange at about even with that weld.

Thanks,
Rey

By DaveBoyer (*****)

Date 05-02-2010 04:47

I would use a shaft material that lends itself better to welding, and follow the appropriate weld procedure. Also, I would increase the fillet size to minimum 1/2 the flange thickness each side.

The HAZ from the weld is likely responsible for initiating the shaft fracture.

By bozaktwo1 (***)

Date 05-04-2010 17:10

Agree, and with the combination of such a small fillet and 70S-6 wire...IMO 80S would have been better here. Overengineered and underwelded. :)

By R McLead (**)

Date 05-05-2010 14:48

bozaktwo1,
The fillet weld size detailed is marginal and the 80S wire would be closer to the tensile strength of the base metal. I put an ECR in to change size of weld and preheat but the 80S change will probably be rejected.

Thanks,
Rey

By Blaster (***)

Date 05-01-2010 20:50

Looks like a preheat issue to me.

I don't see any failure in the weld except as you stated, it appears to have LOF to the flange at what is likely the weld start. If I am reading the pictures right, it looks like the ER70S-6 weld pulled base metal out of the 1045 shaft all the way around.

By R McLead (**)

Date 05-02-2010 02:56

Blaster,
That is correct there is base metal gone all away around also the shaft failed at about where the weld is on the other side of flange.

Thanks,
Rey