Forming Crack-free head 1

[SaeidNorouzi]

Hello All,
We are going to form a head for a presser vessel. Its diameter is about 3000mm.
And it is made of A516Grade70 (Thk. is 32mm). Unfortunately, while forming we have cracks on the material (mostly on the smal diameter region) which cause rejection of the
head.
How can we form a crack-free head? Do we have to do the forming in several steps? Do we need heat treatment before forming and between forming steps?
Thank you,
Saied

 

[metengr]

Hot form the plate at 1600 deg F, slow cool and re-heat treat to establish the required mechanical properties. Most likely, you have reached the forming limit of this material when forming cold.

 

[MikeMet]

Since you may not be able to hot form at 1600F you can always do the forming in stages with very small amounts of deformation and stress relieve at 1150F in between stages. You can also fully normalize the finalized heat to get back a homogeneous fine grain structure and homogeneous properties.