Steel Plate Material Clarification

To make what?

What is LSS?

LSS mean here in this question name of company ( Latrobe Specially Steel company )

LSS mean Last Song Syndrome ( during talking about materials) may be

LSS mean Line sharing service ( during talking about commerial bids )

dear Anonymous poster #1

Greeting to you

N letter is used to mean Normalized.

Normalizing is heating at 920 °C approx. to full austenitizing the steel and then cooling in still air.

It is a mandatory requirement of the Code (Section II Part A in SA-516 heat treatment para. 5.1 page 938) that the plate SA-516 shall be normalized if thickness is over 40 mm otherwise it is an additional requirement for less than or equal to 40 mm.

The main differences between normalized material SA-516 and non- normalized

material SA-516 are :

A) Normalizing is not mandatory till 40 mm. It is a supplementary condition to be specified by Purchaser. When Normalizing is not specified for lower thicknesses , both SA 516 Gr70 & SA 516 Gr70N meet the specifications.

B) Having said that, there is a difference in Impact test requirements. Ref UCS-66. Normalized Grade 70 falls in Curve D where as Not - Normalized Grade falls in Curve B. For Impact test exemption, see also UG-20(f) - (up to 25 mm) & UCS-68(c) -up to 38 mm

C) Fabricator can normalize the plate - UG-85 & UCS-85 apply.

D) Code does not specify single temperature for Normalizing.
It is defined as "Heating above Upper Transformation Temperature and cooling in still air " Normalizing temperature varies with carbon content and is left for fabricator to decide.

AT the end according the conditions of your material SA-516 (thickness, impact test, heat treatment) you can decide if you can use the material as normalized or not.

CONCLUSION : in most case yes you can use the normalized 516N instead of non normalized material 516 even if the thickness 40 mm and less but it means high initial cost for this material