YST 5 for hot rolling winder【Steel casting】

Special Material YST 5★ Durability against high-temperature brittleness
If it could be used under winding condition of being heated bellow 750℃, the excellent
toughness characteristics of YST5 will be kept. When it is exposed for a long time from the tempering
temperature to 780℃(or more), toughness characteristics will be decreased, but because the surface crack
growth is very slow, it does not cause sudden breakages of segments.
★ Durability against Low-temperature brittleness
Even if it is exposed to the embrittlement temperature range of 450 to 500℃ for a long time,embrittlement as observed in high Cr steel does not occur in YST5.
★ Good abrasion resisting property
Even in the condition of high temperature, it has good abrasion resisting property.
★ Good machinability
Good machinability can be confirmed when machining the surface for reusing the segments.
★ High performance and Cost beneficial
Despite its high performance, YST5 has cost beneficial feature because alloy components isfewer than the 12Cr based material(ex.GX22CrMoV12-1).
★ Comparison with GX22CrMoV12-1
Thanks to its excellent heat resistance, abrasion and corrosion resistance, GX22CrMoV12-1
is widely adopted in heavy industrial market such as turbine material of power generation field (Hydraulic,Gas＆Steam turbine, etc) However, Hot-rolled mandrel equipment requires special materials that can beused under conditions of repetitive heating and cooling in many times. Under such harsh conditions forlong time, many heat cracks will occur on the surface. Therefore, in order to avoid breakages and crack
growth on the surface of segments, the material of the segment must be given top priority with sufficient
fracture toughness properties which makes the occurrences and the progress of cracks delay. This point is
the most important property to eliminate the sudden stop of facilities, and YST5 is the most suitablematerial.
The comparison of the mechanical properties and evaluation of YST 5 and GX22CrMoV12-1

Material

YST 5
GX22
CrMoV
12-1

Proofstress(N/mm2)

Tensilestrength(N/mm2)Elongation

560

Charpyabsorbed
energy(J)Temp.20℃

Hardness(%)

Reductionof area(%)

710227033115GOOD

GOOD

EXCELLENTEXCELLENTGOOD

EXCELLENT

60078518484025

EXCELLENTEXCELLENT

GOOD

GOOD

EXCELLENTNO GOOD(HS)【 Reference photography 】 Example of cracks in GX22CrMoV12-1

DEEP HARMFUL CRACK
in GX22CrMoV12-1

★ YST 5 Winding surface status after use

After winding 1,200,000 tons!!

（still usable/stock for emergency）

As a feature of YST 5,
although a HONEYCOMB PATTERN appears on the surface,
it is very shallow and NEVER progresses to HARMFUL CRACKS.

【Not Re-machined】

After winding

1,500,000 tons
In some mills, the sameamount of coils are able tobe wound further byRe-machining the surface
after use.

Since 1904, our group has been dedicating to offer customer’s solutions manytimes. In steel and iron industry, we have approached improvement of our materials to bedurable for sever conditions with considering cost. Through the business we have been
earned great reputation in Japan. Now, based on the experiences in Japan, we are proud ofexpanding our business to the US market and really would like you to feel high-end quality. It
must be the most extraordinal solutions for you.
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