material with high phosphorus. That is why I've often seen a project
specification says about maximum content of phosphorus. To avoid micro
cracking, it was suggested to pick up material with good elongation.
Rgds
2011/12/12, james gerald <gerry_tup@yahoo.com>:
> Hot cracking is a cracking mechanism that occurs at high temperature during
> the last solidification phase.
>
> Hot cracking can occur because of
>
> 1. Low melting eutectic like Sulphur,Arsenic,lead which forms low melting
> compounds with iron
> 2. Wide gap between the liquidus and solidus curve.
>
> The above associated with the welding stress.
>
> What happens in the weld is that, the weld metal tends to solidify from the
> corners of the base metal to which it is joined. As the solidification
> proceeds the low melting eutectics are concentrated in the centre and
> remains liquid which is torn apart by the stress associated with the welding
> resulting in centreline crack.
>
> The presence of delta ferrite about 5-10% solves this hot carcking problems.
> Since delatferrite is the first phase that forms from the liquid phase and
> which has a higher solubility limits for the low melting eutectics(impourity
> Atoms), there will not be any low melting eutectics during the last phase of
> solidification and hence no hot carcking.
>
> The gap between liquidus and solidus curve can be controlled by limiting the
> interpass temperature below 150degC which promotes fast cooling and hence no
> hot cracks.
>
> Thanks & Reagrds
>
> J.Gerald Jayakumar
> 00968-93281596
>
>
> ________________________________
> From: Ary Agung Prasetyo <ary_mt05@yahoo.com>
> To: "materials-welding@googlegroups.com"
> <materials-welding@googlegroups.com>
> Sent: Sunday, December 11, 2011 8:49 PM
> Subject: [MW:13192] Hot cracking mechanism in stainless steel
>
>
> Dear experts,
>
> can expert explain to me how hot cracking mechanism in stainless steel?
> many reference shows delta ferrite is a cause of hot cracking in SS, but i'm
> still confuse about the mechanism.
> Thanks
>
>
> Salam,
>
>
> Ary
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