March 17, 2020
Sanyo Special Steel Co., Ltd.

News Release

Superior High-Temperature Strength and High-Temperature Corrosion Resistance

Successful Development of Heat-Resistant Steel for Use inNext Generation Recuperators-Contributing to reductions in fuel use and CO2 emissions through optimization of energy consumption in various types of industrial furnaces-

Sanyo Special Steel Co., Ltd. (Representative Director: Higuchi Shinya, Main Office: Himeji) has successfully
developed heat-resistant steel for use in next-generation recuperators, meant to help contribute to the optimization ofenergy consumption through reductions in fuel use and CO2 emissions at various industrial furnaces.
A recuperator is a device that collects wasted heat in order to optimize energy use in various industrial furnaces thatutilize fuels such as LNGs. Our company develops, manufactures, and sells the “SIC series” of high chromium ferritic
heat-resistant steels (SIC9, SIC10, SIC12) for use in the heat exchanger tubes of such recuperators, and we haveestablished a strong reputation over many years with our customers, particularly heat-recovery device manufacturers, but
the heat-resistant steel we recently developed is based off of the “SIC12,” which boasts the highest oxidation resistanceand high-temperature corrosion resistance of the SIC series, with the new steel exhibiting much higher high-temperaturestrength than the “SIC12.”
By using this heat-resistant steel in the heat exchanger tubes of recuperators, we can contribute to reductions in fueluse and CO2 emissions by increasing energy efficiency at all of the various industrial furnaces.

High-temperature strength(Creep rupture strength) GOOD

■Development History of Heat-Resistant Steel for Use in Next Generation Recuperators
Industrial furnaces such as melting furnaces, heating furnaces, andheat treatment furnaces, which are used in the ferrous metals,
non-ferrous metals, and ceramics industries, increase energy efficiency
by recycling the heat of gases emitted after combustion as preheating
Contributing to reductions infor combustion air through the use of waste heat recovery devices.
fuel use and CO2 emissions
Recuperators (heat-exchange types) are widely used in waste heatthrough optimization of energy consumption
recovery devices, and users expect greater energy efficiency from suchdevices in order to further reduce fuel use and CO2 emissions. As
Developedincreasing a recuperator’s ability to collect higher temperatures ofSteelwasted heat is an effective way to increase its energy efficiency, it isDrastic Increase in
essential to increase the heat resistance of heat exchanger tubes. The
High-Temperature Strength
SIC series, which has traditionally been our company’s response to theSIC12
need for heat-resistant steel in recuperators, ensures high-temperature
EN1.4762
SIC9SIC10
strength that can withstand current usage environments through solidEN1.4724
EN1.4742
solution strengthening of added alloying elements, but in order tofurther increase energy efficiency, development of heat-resistant steel
Oxidation resistance,
GOOD
high-temperature
with high-temperature strength capable of withstanding even greater
corrosion resistancetemperature of waste heat is necessary.
To that end, we focused on strengthening of material through the precipitation of intermetallic compounds, and by
optimizing precipitation state of intragranular and intergranular intermetallics under high-temperature environments throughour unique alloy design and structural control technologies based on developed experience and knowledge, we thereby
successfully developed heat-resistant steel that retains the high-temperature corrosion resistance of the SIC12 while vastly
expanding upon its high-temperature strength.
Note that high chromium ferritic heat-resistant steel isgenerally thought of as a difficult-to-work-with material
given its large amount of alloying elements like chromium,Developed Steel
SIC12silicon, and aluminum. Using the manufacturing technology
and experience we have built up in developing our SIC series,
we have established the technology to manufacture theseamless steel tubes appropriate for heat exchanger tubes inrecuperators, and are in the process of preparing to supply our20mm
20mm
customers en masse.

Application of this steel will allow recuperators to collect wasted heat at even higher temperatures, further increasing theenergy efficiency of each of the various industrial furnaces, thereby reducing both fuel use and CO 2 emissions.
By developing a new, specialized steel product through the use of our microstructural control technologies that realize
high-performance capabilities in materials, and our manufacturing technology for difficult-to-work-with materials, we willcontribute to the realization of a sustainable society and meet the varied and advanced technological needs of our customers.

EndFor inquiries: Sanyo Special Steel Co., Ltd. TEL: 079-235-6002

【Reference】■Explanation of Terms-Recuperator
Waste heat recovery devices are installed inside the fluesof various types of industrial furnaces that use fuels such as
LNGs, heavy oils, and cokes, and utilize the heat fromemitted gases to preheat the combustion air.
Many of these waste heat recovery devices utilize“recuperators” (heat-exchange types) that collect heat byconducting the heat of emitted gases into combustion air
through the use of heat exchanger tubes.
Heat exchanger tubes conduct the heat from emitted gases
into the combustion air, and as such are exposed tohigh-temperature corrosive environments through whichgases emitted after combustion travel; therefore, materials forsuch tube must possess high corrosion resistance against
high-temperature gases and combustion ash, which contain
substances such as sulfur and vanadium arising out ofhigh-temperature oxidation and fuel combustion, as well as
high-temperature strength that can withstand thermal
deformation caused by high temperatures.

[Structure of Recuperators]-SIC Series
High-temperature corrosion-resistant stainless steels developed by Sanyo Special Steel. This long-selling products
contain alloy elements such as silicon and aluminum in high chromium ferritic stainless steel for excellent
high-temperature oxidation resistance and enjoy extensive and wide-spread use as heat exchanger tube in recuperators.
The lineup includes variants incorporating different quantities of chromium for use in different usage environments(maximum temperatures): SIC9 (13% Cr), SIC10 (18% Cr), and SIC12 (24% Cr) which are compatible with EN1.4724,
1.4742, 1.4762, respectively.
-Solid solution strengthening
A mechanism for strengthening metallic materials. With steel, solid solution strengthening refers to the material’sresistance to changing shape caused by the strain, that can act as obstacles of atom movement, resulting from atom size
difference when an alloy element is melted into solid iron acting as a solvent element (called the solid solution).
-Precipitation of intermetallic compounds
Generally speaking, most materials grow weaker in high-temperature environments due to an increase in movement ofatoms within the material (the material is more likely to change shape), but by precipitation of fine intermetallic
compounds with ordered crystalline structures, a pinning effect arises that controls the movement of atoms, thereby
making it possible to strengthen materials.
-High chromium ferritic heat-resistant steel
A heat-resistant steel that has had its oxidation resistance enhanced by adding chromium (Cr) to ferritic stainless steel,of which Type 430 is a representative example. When compared to nickel-based alloys and austenitic heat-resistant steel,this material is cheap with high heat conductivity, and though the high-temperature strength is less robust, the smaller
thermal expansion makes it harder for oxidation scale separation to occur within high-temperature environments, giving itstrong oxidation resistance. Further, given the large amount of alloy elements contained, this material is classified as a
type of steel that is difficult to manufacture or process (difficult-to-work-with material).
-High-temperature strength (creep rupture strength)
Creep resistance of a material under high-temperature environments. Creep refers to a phenomenon where an objectchanges shape over time due to a constant load (stress) applied to the object while under a high-temperature environment,
and when creep sets in, the object’s shape changes slowly over time until it ultimately ruptures.
End