Cross Rolled Plates 3

[bmoorthy]

Hello all

what is a cross rolled plate?

What are its applications (Under what circumstance one specifies cross rolled plates)?

Is there an ASTM/BS/ BSEN standard that deals with such plates?

Can a SA 516 Gr 60 plate be a cross rolled plate?

 

[SMF1964]

Someone correct me if I'm wrong (it's been a few years), but I believe cross-rolling is an attempt to avoid the directional variation of mechanical properties that you get with rolled plate. That is, the tensile strength of a test sample cut parallel to the rolling direction is significantly different than the strength of a sample cut from the same plate but perpendicular to the rolling direction.

There's nothing in the ASME spec to my knowledge that prohibits this fabrication practice. As long as it meets the chemistry, mechanical, microstructural and finish requirements of the spec, how it gets there is not specified.

 

[metengr]

A cross rolled plate is a plate that is rolled in two different directions. Cross rolling is done with hot or warm to reduce directionality effects on mechanical properties. This can be applied to plates prior to improve forming operations for shells or heads.

Yes, SA 516 Grade 60 can be specified cross rolled provided you state this requirement for the mill.

 

[arunmrao]

I can generally say that cross rolling is done to negate the effect of grain orientation. The aim is to make the properties equal in longitudinal and lateral directions. The elongated grain structure is broken and you get more or less round grains.

One ready exaple though not so simple is the high silicon sheets used in electrical transformer. They are what is commonly called as non grain oriented . This property minimises the eddy current losses.

 

[bmoorthy]

If a plate is normalized after rolling (Say a 2" SA 516 gr 60)then does it really matter what the rolling direction was since theoretically the plates grains get reorganized?

Is there a specific application where one comes across the requirement to use cross rolled plate.

 

[RPstress]

Most Ti alloy plate in airframe is cross rolled. The properties come out very close in the two directions.

 

[metengr]

Perhaps the best way to evaluate cross rolled plates is to decide on what you need for application;

1. Cross rolling can be used to increase the width of the plate for certain forming applications.

2. Repeated cross rolling where the plate is turned transverse to the previous rolling direction can be used to reduce directionality or spread in mechanical properties related to the direction of forming - mechanical properties in the longitudinal direction versus transverse direction. A normalization heat treatment (rapid cool or quench) will provide a finer grain structure with increased mechanical properties thru thickness. However, the directionality of the mechanical properties still remains between the longitudinal (rolling) and transverse directions in the rolled plate versus cross rolled plate.

3. Cross rolling increases cost

So, you have to decide if either benefits in 1 and 2 mentioned above offset the increase in cost.

 

[EdStainless]

Cross rolling is common in Ti (and some other alloys) because they develop much more severe anisotropy than alloys with a cubic structure (Fe based).

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[zirconium]

If it is because of material texture, sometimes we need to do cross rolling to break the strong texture of the material.
Texture correspond to orientation of grains in polycrystal material.
Simple example, in strongly textured Al sheet (for ex. 80% of grains are oriented with their (100) axis parallel to normal of sheet plane), there will be earing defect after deep drawing.
Cross rolling can correspond to 90° orientation change at each rolling pass, or 45° if necessary.
You can always see this website about earing problem:

http://neon.mems.cmu.edu/rollett/27750/Beer_Cans_1Feb05.ppt