materials-science and technological background for developing advanced thermal power equipment

ISSN 0040�6015, Thermal Engineering, 2012, Vol. 59, No. 4, pp. 266–273. © Pleiades Publishing, Inc., 2012.Original Russian Text © A.V. Dub, V.N. Skorobogatykh, 2012, published in Teploenergetika.

266

Along with improvement of gas and combined�cycle technologies, construction of modern large�capacity power units firing coal and operating at ultra�supercritical steam conditions, which comply with themodern requirements for economic efficiency, envi�ronmental effects, reliability, and service life, andmastering operation of these units is the main line inwhich thermal power engineering is being developedin industrially advanced countries.

Use of increased parameters of steam in thermalpower engineering makes it possible to solve a fewmost important problems, all in a comprehensivemanner:

(i) achieving better efficiency of thermal power sta�tions (TPSs);

(ii) producing smaller amounts of polluting emis�sions in the form of nitrogen oxides, sulfurous com�pounds, and carbon dioxide;

(iii) achieving active involvement of solid, i.e., leastnoble fuel in power engineering, the reserves of which,unlike those of gaseous fuel, will last for hundreds ofyears.

Figure 1 shows the structure characterizing theactual consumption of different kinds of fuel by Rus�sian power stations in 2005 and 2008, as well as theirsupposed consumption according to the Energy Strat�egy of Russia for the Period of up to 2030. The con�sumption of coal fuel at TPSs must increase from77 million t in 2005 to 100 million t in 2013–2015, to137 million t by 2022, and to 185 million t by 2030.

The fraction of coal in the fuel balance of TPSs willincrease from 27% in 2005 to 40% in the period up to2030. Solving of matters concerned with its efficientand environmentally clean use is of primary impor�tance for Russia, also in view of the need to furtherincrease the export of natural gas.

At present, more than 40 coal�fired power units forultrasupercritical (USC) steam conditions (with a

temperature of higher than 580°С and pressure ofhigher than 25 MPa) are in operation in Europeancountries, Japan, the United States, and China. Thereare plans according to which more than 50 coal�firedthermal power units with capacities of 500–110 MWare supposed to be commissioned in these regions inthe period up to 2015.

Increasing the parameters of steam (serving asworking fluid), the achieved levels of which are as highas 600–610°С and 30 MPa in modern USC coal�firedpower units and 620°С and 35 MPa in new types ofpower units makes it possible to obtain the electricalefficiency equal to 45–47% as compared with 32–40% achieved in Russian power installations for highand supercritical pressure operating at pressures rang�ing from 9 to 25 MPa and live steam temperaturesequal to 545–560°С.

The problem of constructing USC power units andincreasing the operating parameters for other thermalpower installations cannot be solved without having adomestic materials�science and technological back�ground for their production. First of all, production ofa new class of heat�resistant materials must be devel�oped and mastered, in particular, materials for suchimportant high�temperature and heavily loadedequipment components as rotors of steam turbines,steam lines, steam superheaters, and headers of boilerequipment.

Structural materials for these elements must meetthe following requirements:

(i) They must have the required long�term strengthfor a service life of 200000 h at a working temperatureof 600°С or higher.

(ii) They must have high long�term plasticity.(iii) They must have the optimal critical brittleness

temperature.(iv) The material must retain high levels of plastic�

ity and toughness for the entire service life.

Materials�Science and Technological Background for Developing Advanced Thermal Power Equipment

A. V. Dub and V. N. SkorobogatykhOAO NPO TsNIITMash, ul. Sharikopodshipnikovskaya 4, Moscow, 115088 Russia

Abstract—Results from a study of heat�resistant chromium steels intended for making high�temperaturecomponents of prospective thermal power equipment are presented. It is shown that the developments of newmaterials that have been implemented in the Russian industry create the necessary background for construct�ing thermal power units for a temperature of up to 620°C.

DOI: 10.1134/S0040601512040039

THERMAL ENGINEERING Vol. 59 No. 4 2012

MATERIALS�SCIENCE AND TECHNOLOGICAL BACKGROUND FOR DEVELOPING 267

(v) The material must have satisfactory resistanceto corrosion effect of high�temperature steam mediumand fuel combustion products (for heating surfaces).

(vi) The material must be well amenable to techno�logical processes used in the course of its metallurgicalproduction and manufacture of equipment (during itsmelting, forging, hot deformation, welding, and ther�mal treatment).

The results of comprehensive research and designworks carried out in Russia and abroad [1–3] made itpossible to unambiguously determine the most suit�able and economically efficient class of materials formaking heavily loaded elements of thermal powerunits for ultrasupercitical parameters: these are mar�tensitic and martensitic–ferritic chromium heat�resistant steels with the optimized polycomponentdoping, which are able to meet the existing and pro�spective technical requirements provided that furtherimprovements are made in the quality of their produc�tion.

In development of new materials, the method ofmulticomponent doping showed itself as the most pro�spective one, the use of which makes it possible toobtain high heat�resistant properties with the minimalcontent of doping elements, which are frequentlyexpensive and scarce. A number of foreign and Rus�sian steels used for making the equipment of USCpower units have been developed using this method,including such steel grades as X10CrMoVNb (R�91),10Kh9MFB (DI82), X11CrMoWVNb (E�911),X10CrMoWNbN (R�92).

Heat�resistant chromium steels differ from austen�itic steels that are traditionally used in the range oftemperatures above 600°C in having smaller coeffi�cients of linear expansion and heat conductance (by afactor of 1.3–1.5). With the commensurable levels ofservice and technological characteristics, this makes itpossible to obtain essentially smaller temperaturestresses, which helps to prevent development of flawsin the metal due to local changes of shape, thermalfatigue, and creep. A relatively low cost of metallurgi�cal semifinished products fabricated of heat�resistantchromium steels is another unquestionable advantageof them.

Obtaining high�quality forgings of rotors weightingfrom 10 to 120 t (for USC power units with capacitiesof 200–1000 MW) made of comprehensively dopedhigh�purity chromium steel, with the required anduniform level of service properties over the forging sec�tion and length, including its viscoplastic characteris�tics, long�term strength, and resistance to brittle frac�ture, is the key problem that has to be solved for sup�porting the production of equipment for thermalpower units with the necessary billets and semifinishedproducts.

The modern highly heat�resistant chromium steelsof the martensite (martensite–ferrite) class madeusing special technologies of melting, deformation,and thermal treatment that have been developed andare being put in use in foreign and domestic industriesmust make it possible to meet the following level ofrequirements imposed on the rotor material:

(i) The long�term strength must be no less than70–100 MPa for 100000 h of operation at a tempera�ture of 600–620°С.

(ii) The long�term plasticity must be no less than10%.

(iii) The fracture toughness must be no less than70 MPa m0.5.

(iv) The critical brittleness temperature must be nohigher than 20–40°С.

Starting in 2005, specialists of NPO TsNIITmashbegan to develop and master commercial productionof Grade 12Kh10M1V1FBR heat�resistant chromiumsteel. Its composition was developed, laboratory meltswere studied, pilot industrial forgings of rotors made ofnew steel were obtained, and programs of qualificationtests aimed at determining the necessary set of techno�logical and service properties were implemented to aconsiderable degree. Concurrently, the problem ofbringing the developed composition to under theinternational standards applied to similar rotor mate�rials, namely, Grade X12CrMoWVN6N10�1�1(Europe) and HR 1100 (Japan) steels was solved.

The chemical compositions of these materials werebrought sufficiently close to each other (Table 1), butthe composition of Grade 12Kh10M1V1FBR steelwas optimized in the direction that guarantees obtain�ing the required level of characteristics and propertiesof the metal of forgings as applied to the existing tech�nological process of metallurgical production used atRussian enterprises, first of all, OOO OMZ�Spetsstal’.

300

200

100

02020�2013�20082005 2030

2015 2022

Years

Fuel oilCoalGas

Con

sum

ptio

n o

f fue

l in

th

e th

erm

alpo

wer

indu

stry

, mln

/yr

Fig. 1. Structure of the consumption of different kinds offuel by Russian thermal power stations.

268


DUB, SKOROBOGATYKH

A pilot commercial forging of a high�pressure rotormade of high�chromium steel was produced at OMZ�Spetsstal’ in 2007 (Fig. 2). A special sample 700�mmlong and 700�mm in diameter was organized in theforging zone, which was intended for optimizing tech�nological parameters, primarily the thermal treatmentconditions.

The forging manufacture technology included thefollowing stages [4]:

(i) melting in a 50�ton electric arc furnace;

(ii) off�furnace treatment in a ladle–furnace instal�lation;

(iii) pouring in a vacuum chamber (the 1st version);

(iv) electroslag remelting (the 2nd version);

(v) forging the rotor billet from an ingot;

(vi) preliminary thermal treatment;

(vii) final thermal treatment;

(viii) mechanical processing;

(ix) examining the quality of metal; and

(x) carrying out qualification tests.

An analysis of the chemical composition of theforging metal showed that the metal had traces of car�bon liquation processes (the content of which variedwithin the range 0.11–0.15%). The maximal changeswere revealed in the distribution of Mo and were equalto 0.1% (0.9–1.0%). The content of other doping ele�ments was in line with the requirements listed in Table 1,and no essential deviations of this content wererevealed in different parts of the forging.

Contamination of metal with nonmetallic inclu�sions was estimated, and it was found from that esti�mation that that the forging metal had satisfactorypurity except with a local zone in the rotor’s lowerjournal (which corresponds to the ingot’s bottomzone), which contained stringer�type oxides and brit�tle silicates up to 15 µm in size.

The microstructure of all studied samples corre�sponded to tempered martensite with a uniformly dis�tributed carbide phase. No structurally free delta fer�rite was found in the forging metal.

The sample was subjected to thermal treatment inaccordance with the following schedule: oil quenchingfrom a temperature of 1050°С, intermediate temperingat 570°С, and final tempering at 690–700°С for 25 h.

Test results showed (Table 2) that the yield strengthof the sample metal varied from 590 to 640 MPa, itsimpact toughness was at a level of 84–175 J/cm2, andthe transitive brittleness temperature ranged fromminus 12°С in the axial zone to plus 4–8°С in the sur�face volumes. It is important to note that in the rangeof working temperatures from 550 to 620°С, Grade12Kh10M1V1FBR steel has high strength character�istics (at 600°С σ0.2 = 355–385 MPa and σt = 380–

Table 1. Chemical composition of foreign and Russian grades of high�chromium heat�resistant steel for high�temperaturerotors of steam turbines

Steel grade (country) C Si Mn S P Cr Ni

X12CrMoWVN6N10�1�1 (Europe)* 0.12 ≤0.1 0.50 ≤0.01 ≤0.01 10.0 ≤0.80

HR 1100 (Japan)* 0.14 ≤0.15 0.50 ≤0.01 ≤0.01 10.0 ≤0.60

12Kh10M1V1FBR (Russia) 0.10–0.14 <0.1 0.20–0.40 ≤0.01 ≤0.01 9–10.5 0.3–0.5

Steel grade (country) Mo W V Nb B N

X12CrMoWVN6N10�1�1 (Europe)* 1.0 1.0 0.20 0.05 – 0.05

HR 1100 (Japan)* 1.2 0.8 0.20 0.05 – 0.05

12Kh10M1V1FBR (Russia) 0.9–1.1 0.9–1.1 0.18–0.25 0.04–0.06 0.003–0.005 0.03–0.05

* Average values or limitations for the content of elements are given.

Trial billet

5570 ±60

±30

±16

±18

±60

±20

620 1105 1765 455±30

1200 425

SampleSample

∅71

5

∅84

5

∅11

35

∅76

0

±18

±18

∅54

5

∅53

5

(а)

(b)

Fig. 2. Pilot industrial forging of a high�pressure rotor ofGrade 12Kh10M1V1FBR steel. (a) Forging sizes and (b)external appearance of the forging.



415 MPa) and a weak temperature dependence, whichtestifies that this steel has high thermal stability.

The properties of a sample of the experimentalrotor forging were analyzed, and it was shown fromthat analysis that with the selected schedule of thermaltreatment, the strength category KP�60 and high char�acteristics of impact toughness were obtained (by afactor of 2–3 higher than those stipulated by the regu�latory requirements). However, such strength levelcorresponds only to the lower level of regulatoryrequirements; therefore, the schedule for thermaltreatment of the forging was modified so that the finaltempering was carried out at a lower temperature equalto 680–690°С for 20 h.

On finishing the thermal treatment in accordancewith the modified schedule, the forging and the pilotcommercial rotor forging were cut into billets of sam�ples for carrying out preliminary acceptance tests andthen qualification tests. The results obtained frominvestigations of mechanical properties showed thatthe strength category increased to KP 70 (Table 2).The yield strength increased by 100–150 MPa, theultimate strength increased by approximately100 MPa, and the relative elongation slightlydecreased to 14.5–18.5%. The above�mentionedimprovement in strength characteristics is accompa�nied by a considerable drop of impact toughness andincrease of transitive brittleness temperature to thelimiting values. It should be pointed out that the marginavailable for improving viscous�plastic properties can berealized through achieving still better purity of metal andits structure, primarily by incorporating electroslag

remelting of ingot into the technological process, whichis supposed to be done at the next stage of work.

Long�term strength tests of the rotor forging metalwere carried out in the range 600–700°С on the metalof the surface zone, central part, and zone lying at adistance equal to 0.25 of the forging body radius. Themaximal duration of the tests exceeded 15000 h, andthe overall base of tests was equal to 200000 h. Thegeneralized long�term strength characteristics ofGrade 12Kh10M1V1FBR steel are shown in Fig. 3,which includes data both on laboratory melts and onthe pilot commercial forging. A comparison betweenthe obtained data and the data for Grade

Table 2. Mechanical properties of the material of a rotor forging made of Grade 12Kh10M1V1FBR steel

Requirements for material and sub�

jects of study

Cutout direction

Conventional yield strength,

N/mm2

Tensile strength, N/mm2

Relative elongation, %

Impact toughness,

J/cm2

Critical brittle�ness tempera�

ture, °C, no higher than

No less than

Design require�ments

Longitudinal 540 735 11 39 40

Tangential 590600

735750 13 39 40

Experimental billet of a high�pressure rotor (sample No. 2)

Longitudinal 590610

710750

1920

84121

+8

Tangential 590600

730750

18.519.5

164175

–12

Rotor forging Longitudinal 700760

820880

18.517

51.040.5 +39

Tangential 700790

820810

16.516 710 +26

60

400

1000600

200

100

403130292827 32

Parameter P = t(30 + logτ) × 10–3

σ58

010

5

σ60

010

5

σ62

010

5

I

II

σ63

010

5

123

456

Str

ess σ

, М

Pа

Fig. 3. Results from long�term strength tests of the materialof a pilot industrial forging made of Grade12Kh10M1V1FBR steel. (I) Mean line for Grade12Kh10M1V1FBR steel, (II) mean guaranteed line forGrade E 911 (X11CrMoWVNb9�1�1) steel; (1) laboratorymelting, rods; (2) rotor: the outer surface of ring no. 1; (3)rotor: the outer surface of ring no. 2; (4) rotor: the centralpart (0.25 radius from the center); (5) rotor: the centralpart (immediately after ring no. 2); and (6) experimentalrotor forging.

270


DUB, SKOROBOGATYKH

X11CrMoWVNb10�1�1 steel shows that the metal ofthe studied forging made of Grade 12Kh10M1V1FBRsteel outperforms the former by 15–25% in long�termstrength characteristics; this difference grows as thetemperature increases from 600 to 650°С. The calcu�lated long�term strength limit equal to 100 MPa for100000 h corresponds to a temperature of 620°С anddetermines this temperature by this criterion as themaximal one for using the above�mentioned composi�tion of heat�resistant steel.

The level of properties that was recorded in studiesof forging metal on tangential samples taken from theforging body surface was close to the lower permissibleboundary both in terms of impact toughness and tem�perature of brittle–ductile transition (+39°С). Figure 4shows data obtained from determination of the condi�tional values of fracture toughness and critical brittle�ness temperature according to the master curvemethod on Type ST�1T samples. The brittleness tem�perature obtained according to this method was found

to be 21°С, which is consistent with the data obtainedon the impact toughness of the forging metal.

Thus, the developed composition of Grade12Kh10M1V1FBR steel brought to a common stan�dard with Grade E�911 steel, which is its basic foreignanalog, corresponds to the design level of mainmechanical properties, long�term strength, and resis�tance to brittle fracture. The technology for manufac�turing rotor forgings with the use of open melting andtreatment on a VRV installation, which has beendeveloped and implemented at OMZ�Spetsstal’,makes it possible to obtain rotor billets made of heat�resistant chromium steel, which are sufficiently uni�form in chemical composition and in the main char�acteristics of metal, including two extreme strengthcategories of this material. The long�term strength ofthe metal of the pilot commercial forging made ofGrade 12Kh10M1V1FBR steel, which is the mainassessment indicator, exceeds the standardized levelfor Grade E�911 steel, which its foreign analog, by15–30%.

As far as manufacture of rotor forgings made ofheat�resistant chromium steel is concerned, Russianmetallurgical works are in the stage of transition to itsindustry�scale production. As regards the manufactureof pipes, similar process took place in the period fromthe late 1990s to early 2000s.

In the late 1980s, Grade 10Kh9MFB heat�resistantchromium steel was developed, after which its com�mercial production was mastered [5]; GradeX10CrMoVNb (P�91) steel, which is widely used formaking thermal power equipment, is an analog of theformer. By now, manufacture of Grade 10Kh9MFBsteel has been mastered at a few Russian metallurgicaland pipe works (Table 3). The overall amount of thissteel manufactured since the time its production wasmastered totals more than 2000 t. Commercial use ofpipes and forgings made of this steel for headers, steamsuperheaters, and steam lines was tried out at OAOZiO�Podolsk, OAO TKZ Krasnyi Kotel’shchik, OAOBelenergomash, OAO LMZ, and other works, also inmaking the boiler for the 300�MW power unit at theWang�Bee thermal power station in Vietnam. Atpresent, a set of pipelines and a set of pipe elementswith external diameters of up to 530 mm made of thissteel have been prepared at Belenergomash for thesteam line of the 225�MW power unit at the Kharan�orsk district power station with the working steamparameters 565°С and 15 MPa.

We consider the problem of mastering the produc�tion of long (21–25 m) tubes of small standard sizesmade of Grade 10Kh9MFB steel for manufacturing thefinned heating surfaces used in the high�pressure part ofheat�recovery boilers of combined�cycle power plants(CCPs). Specialists of the Sinarsk and Pervouralsk PipeWorks are busy with solving this problem.

200

150

100

50504020100 30

Test temperature, °C

Fra

ctur

e to

ugh

nes

s, M

Pa

m0.

5 ST�1T5% curve

95% curvecurve

Fig. 4. Fracture toughness and critical brittleness temper�ature according to the method of master curve for themetal of forging made of Grade 12Kh10M1V1FBR steel.

Table 3. Main producers and amount of production of tubebillets, forgings, and pipes made of Grade 10Kh9MFB steel

Kind of semifin�ished product Manufacturer Amount

of production, t

Tube billet Zlatoust Metallurgical Works

600

Ural’skaya Kuznitsa 230

Krasnyi Oktyabr’ 530

Forgings OMZ Spetsstal’ 120

Boiler tubes Pervouralsk New Tube Works

680

Steam line tubes Chelyabinsk Tube Rolling Works

200



A set of regulatory documents is available for pipesand forgings made of Grade 10Kh9MFB steel [6],which contains the necessary data for carrying outstrength calculations, as well as guidelines for the con�ditions and technology of using them for boiler andsteam line equipment. More than 30 melts of Grade10Kh9MFB steel had been studied by 2010; long�termservice life tests had been carried out for the time basisequal to 30000 h of direct tests with the total time oftests equal to around 106 h on the metal of pilot indus�trial (Fig. 5) and industrial melts (Fig. 6). The stan�dard requirements for the resistance to long�term frac�ture and other normative characteristics are at the levelof similar requirements for Grade X10CrMoVNb (P�91)steel, which is an analog of Grade 10Kh9MFB steel,including welded connections. In accordance with therelevant standards, temperature equal to 600°C is thelimiting one for using this steel grade for steam linesystems and pipelines within the boiler boundaries and620°C for tubes used in heating surfaces and steamsuperheaters of steam boilers. Thus, with the materi�als�science and technological background availablefor this material, the problem of manufacturing pipeelements for USC power units (to a steam temperatureof 590–600°C) at Russian metallurgical enterprisescan be considered to have been solved.

The next necessary step consists in making a shiftfor using heat�resistant materials with which the work�ing temperature of boiler and steam�line equipmentcan be raised to a level of 620°C. Such level of workingtemperatures is in fact achieved at the modern stage ofthe development of USC power units. The most effi�cient method for achieving higher heat resistance ofchromium steels is to replace doping with molybde�num and tungsten by doping with respect to the totalcontent of these elements: 0.5 W + Mo ≤ 1.5%. Theheat resistance of chromium steel vs. the total content

of W and Mo is shown in Fig. 7. Naturally, such shiftmust involve additional activities in the field of mate�rials science, as well as in metallurgical, and othertechnological aspects. The foreign steelX10CrWMoVNbN (P�92) was developed and has nowbeen produced on a wide scale on the basis of thisapproach. Based on the available experience, special�ists of NPO TsNIITmash developed Grade10Kh9B2FBR steel, the manufacturing technology ofwhich has been brought to a level of commercial pro�duction. The totality of the results obtained from thetests for a base of up to 15 000 h (Fig. 8) in the temper�ature range 600–700°С that were carried out at NPOTsNIITmash, NPO Central Boiler–Turbine Institute,and OAO All�Russia Thermal Engineering Instituteallow a judgment to be made that this material can beapplied in terms of the long�term strength criterion ata level of 620°С, which corresponds to the temperaturelevel at which Grade P�92 steel can be used. Grade10Kh9B2FBR steel has successfully passed the stageof laboratory tests, and manufacture of this steel in theform of tube billets has been brought to a level of com�mercial�grade production at OAO Zlatoust Metallur�gical Works according to the following scheme: elec�tric arc furnace–electroslag remelting. Specialists ofOAO Chelyabinsk Tube Rolling Works fabricated pilotindustrial steam line pipes of sizes ∅377 × 50 and 465 ×75 mm from the obtained ingots and subjected these

60

400

1000

600

200

100

403130292825

Parameter P = t(30 + logτk) × 10–3

σ60

010

5

I

IIStr

ess σ

, М

Pа

2726

σ60

02

× 10

5

Fig. 5. Results from long�term strength tests of a pilotindustrial batch of Grade 10Kh9MFB�Sh steel. (I) Para�metric long�term strength curve for Grade 10Kh9MFB�Sh steel made as per TU (Technical Specifications) 14�3R�55�2001 and (II) permissible deviation by 20% as per TU14�3R�55–2001 (the results from tests of the metal of ninepilot commercial melts carried out at TsNIITmash, TsKTI,and VNIIAM in the 1990s at temperatures of 500, 550,575, 600, and 650°C with the total duration of 650 000 h,with the test base equal to 29 335 h; the tests have not beencompleted.

1000

100

3130292825

Parameter P = t(30 + logτk) × 10–3

I

II

123

456

Str

ess σ

, М

Pа

σ60

010

5

σ60

02

× 10

5

26 27

7

Fig. 6. Results of long�term strength tests of regularbatches of Grade 10Kh9MFB and 10Kh9MFB�Sh steels.(I) Parametric long�term strength curve for Grade10Kh9MFB steel made as per TU 14�3R�55�2001 and (II)permissible deviation by 20% as per TU 14�3R�55–2001.(1) Pipe with a size of 325 × 34 mm made of Grade10Kh9MFB steel produced by OAO Niko Tube (theUkraine) (According to the TsNIITmash data), (2) pipewith a size of 45 × 3 mm made of Grade 10Kh9MFB�Shsteel produced by PNTZ (according to the TsNIITmashdata), (3) pipe billet made of Grade 10Kh9MFB steel pro�duced by OAO ZMS (according to the TsNIITmash data),(4) pipe billet made of Grade 10Kh9MFB steel producedby ZMZ (according to the VTI data), (5) pipe with a sizeof 42 × 6 mm made of Grade 10Kh9MFB steel produced byPNTZ (according to the data of TsNIITmash and TKZ), (6)pipe with a size of 325 × 34 mm made of Grade 10Kh9MFB�Sh steel produced by YUTZ (according to the data of TsNI�ITmash and Belenergomash), and (7) bend of a pipe with asize of 325 × 34 mm made of Grade 10Kh9MFB�Sh steelproduced by Belenergomash (according to the data of TsNI�ITmash and Belenergomash).

272


DUB, SKOROBOGATYKH

pipes to a full cycle of quality control in accordancewith the technical requirements applicable to steam�line and boiler pipes for high� and supercritical�pres�sure equipment.

At present, the metal of pipes (including weldedconnections and bends) manufactured at OAO Ener�gomash is passing qualification tests, including long�term strength tests, the direct�test base of which hadreached a level of 20000 h by January 1, 2011. The fullcycle of studies will be completed in the first half of2012. The final set of regulatory documents will becompiled and approved by the same time, which willmake it possible to use this material for tube elementsof USC power units and other prospective equipmentoperating at temperatures of up to 620°С.

CONCLUSIONS

(1) Three grades of heat�resistant chromiumsteel—10Kh9MFB, 12Kh10B1M1FBR, and10Kh9B2MFBR—for high�temperature elements ofboiler, steam line, and turbine equipment of prospec�tive thermal power units have been developed, andtheir manufacturing technology has been brought tothe level of commercial production.

(2) The problem of producing rotor forgings madeof Grade 12Kh10V1M1FBR heat�resistant chromiumsteel for power units with ultrasupercritical steam con�ditions has been solved. A model rotor has been man�ufactured, and its metal has passed qualification testsfor confirming its quality and determining the level ofits properties with respect to two extreme strength cat�egories KP 60 and KP 70.

(3) Grade 12Kh10V1M1FBR steel has beenbrought to a common standard with Grade E 941 andX12CrMoWVNbN 10�10�1 steels, which are its foreignanalogs, and meets the characteristics of plasticity andresistance to brittle fracture that are declared for them,while having a higher level of long�term plasticity.

(4) The manufacture of tube billets, pipes, andforgings of Grade 10Kh9MFB steel for making boilerand steam�line equipment operating in the tempera�ture range up to 600°С has been mastered. A set of reg�ulatory documents for this steel has been developed,including documents for application conditions, sup�port of design calculations, and guidelines for con�ducting technological processes. The statisticallymeaningful long�term strength characteristics ofGrade 10Kh9MFB steel have been determined in anormative manner based on the results of testsobtained from more than 30 melts on the time basis ofdirect tests up to 30000 h and the total time basis equalto 106 h. The database for this steel on permissiblestresses should be supplemented for the service lifebase equal to 200000 h over the entire range of temper�atures.

(5) Grade 10Kh9V2FBR steel for making pipe sys�tems of prospective power units with a working tem�perature of up to 620°С has been developed, and itsmanufacture has been brought to the industry�gradelevel. By the end of 2011, the cycle of pilot industrialtests should be completed, and the necessary back�ground should be set up for creating a set of normativedocuments for using this steel in making steam�lineelements of USC power units and other prospectiveequipment.

(6) The developments of new heat�resistant steelsimplemented in the Russian industry form the materi�als�science and technological background for creatingprospective USC thermal power units with a steamtemperature of 600–620°С.

(7) Further practical steps that have to be taken inshifting the Russian machinery construction industryand power industry for wide use of heat�resistant chro�mium steels should involve development of technolog�ical solutions aimed at production of equipment for

160

120

80

40

0

Lon

g�te

rm u

ltim

ate

82

102117

Mo = 1.0 – 1.5%(10Kh9MFB)

str

engt

h σ

600

105,

МP

а

W = 1.0%Mo = 1.0%

(12Kh10M1V1FBR)

W = 2.0%Mo = 0.6%

(10Kh9V2MFBR)

Fig. 7. Long�term strength of 9% chromium steel in con�nection with the level of doping with Mo and W.

1000

100

3837363532

Parameter P = t(30 + logτ) × 10–3

I

II

1234

56

Str

ess σ

, М

Pа

33 34

7600400

200

6040

8

σ55

010

5

σ58

010

5

σ60

010

5

σ62

010

5

σ65

010

5

Fig. 8. Results from long�term strength tests of pilot com�mercial batches of Grade 10Kh9V2MFBR steel. (I) Meanline and (II) permissible deviation by 20%; (1) Ttest =600°C, laboratory melting, rods; (2) Ttest = 650°C, labora�tory melting, rods; (3) Ttest = 600°C, the metal of a steamline pipe with a size of 377 × 50 mm; (4) Ttest = 650°C, themetal of a steam line pipe with a size of 377 × 50 mm; (5)Ttest = 670°C, the metal of a steam line pipe with a size of465 × 75 mm; (6) straight portion of a bend; (7) tensile por�tion of a bend, and (8) uniform welded connections.



modern power units, with setting up a set of computa�tion methods compatible with foreign standards anddocuments for operational checks.

REFERENCES

1. C. Betger and R. W. Vanstone, “Development of 9–12% Cr steels for rotor forgings. A Collaborative Euro�pean Effort in Cost 501/II,” in Proceedings of Interna�tional Conference on Materials for Combined Cycle PowerPlants, Sheffield, UK, June 1991, pp. 119–136.

2. W. T. Bakker and B. Nath, “Development and Testingof Ferritic Steels for Advanced Power Plants: ProgramOverview,” in Proceedings of the 3rd Conference onAdvances in Materials Technology for Fossil Power PlantsEPR. Report 100/462, Institute of Materials, London,2001, pp. 3–7.

3. Ja. Waheshima and M. Mikami, “Manufacturing ofTrial Rotor Forgings of Cost E Steel(X12CrMoWVNbN10�1�1),” in Proceedings of the 16thInternational Forgemasters Meeting IFM 2006), Shef�field, UK, October 2006, pp. 164–178.

4. V. S. Dub, A. V. Dub, V. N. Skorobogatykh, et al.,“New Steels and Their Melting Technologies for PowerInstallations with Ultrasupercritical Parameters,”Tyazh. Mashinostr., No. 12, 13–17 (2009).

5. V. P. Borisov, I. A. Shchenkova, R. M. Zhuchkova, andE. R. Kabanova, “High�Chromium Steels in Construc�tion of Boilers,” Teploenergetica No. 2, 48–52 (1990)[Therm. Eng., No. 2 (1990)].

6. V. N. Skorobogatykh, V. P. Borisov, and I. A. Shchenk�ova, “Prospects for Improving the Tube Products Usedin Manufacturing the Boilers and Steam Lines at High�and Supercritical Pressures,” Teploenergetica No. 4,60–61 (2001) [Therm. Eng., No. 4, 320 (2001)].

materials-science and technological background for developing advanced thermal power equipment

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