Maraging Steel - SUS perspective for round-table discusions

Justin Greenhalgh for the Suspensions group

G050099-00-K

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Outline

Data sources Properties Treatment Unknowns

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Data sources Papers (mostly from VIRGO group) listed in T040083 Direct input

Mike Plissi talked to VIRGO see T040108; Riccardo at SUS meeting see SUS meeting notes

Simple test at RAL Specimens cut from “near surface” and “near middle” of

plate Standard dog-bone specimens failed to give E (T040116 gives the results but not the

realisation that they were flawed) gave strength ~1.9 Gpa

Test of drum-ended wire by Calum Only a single test so far, but 1.4 GPa failure load – did not fail at the junction with

the drum-end

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Properties C250 Maraging Modulus

Used 186 GPa and alpha = 1.36 for the CP (T040153) Deflections were off by a few % but not consistently, so these

values are about right for “generic” use Can now tailor for each blade size (modulo comments to be got

from Mike Plissi) Strength

Around 1.9 GPa yield for plate, ?? For rod/wire Creak resistance

Assumed OK if we keep the stress below 1 Gpa (55% of yield) and do “anti-creep” heat treatment (see below)

Damping Assume Q = 10^4

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Treatment

Detailed in T040108 Propose

Use C250 grade this is one that was used most by VIRGO and so is best

characterised Less difficult to obtain that other grades?

Consider buying a single batch for all AdLIGO blades Aged at 435 for 100 hours (cost implications – is this

necessary?) Anti-creak treatment under load at 100C for 1 week

But does that mean all the blade qualification measurements would have to be done again?

Bake-out should be OK following treatment above ?? E990022-A calls for 200C for SS and 120C for aluminium, so maybe

our anti-creak should be done warmer. And note more recent results from Riccardo and his student.

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Unknowns Creak susceptibility in blades is OK

In wire clamps (maraging?) issue? In blade clamps (maraging?) issue? Workarounds, eg maraging clamps or “smooth root”

blades – but need to know limits to allow cost optimisation.

Availability What’s the “best” grade to use?

Processing details Ground surfaces OK? (new understanding from RdS is

“YES”) 100 hour treatment may be expensive – is a shorter one

OK? Vacuum bakeout effects – Riccardo… Recent result on wires – why so much weaker? Why were some of the CP blades so different from the

others?

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Blade test summary results – 1

collected results

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

-20 -15 -10 -5 0 5 10

variant (mm)

sti

ffn

es

s (

%)

top CES

top VP

mid CES

mid VP

bot CES

bot VP

Top 480*95*4.3Mid 415*59*4.6Bot 635*49*4.2

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Blade test summary results - 2

stiffness-thickness

-0.1

-0.08

-0.06

-0.04

-0.02

0

0.02

0.04

-0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4

thickness error (%)

sti

ffn

es

s e

rro

r (%

) top CES

top VP

mid CES

mid VP

bot CES

bot VP