On 12月13日, 下午12时14分, Fitria Rahman <t.chint...@gmail.com> wrote:
> In addition to what Jayakumar said, hot cracking is common in base
> 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_...@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_m...@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,
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