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1

Evaluation of resistance of duplex steels to sulfide stress cracking at various load modes

Jonsta P., Sojka J., Matocha K., Jonsta Z., Konecna K.

Hutnik, Wiadomości Hutnicze

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2012

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Vol. 79, nr 9

708--713

EN

The paper deals with influence of various load modes and microstructural characteristics on evaluation of resistance of duplex steels 22Cr05Ni to sulfide stress cracking (SSC). Two heats of duplex steel were used. Each of these heats was evaluated both in as-supplied state after rolling and after homogenisation annealing, and also in the state after laboratory annealing by the mode 800 oC/5h/air. Microstructure of steel in the as-supplied state was ferritic-austenitic, in the state after annealing it was ferritic-austenitic with occurrence of the phase σ at the majority phases interface. Testing of resistance of duplex steels was performed in accordance with the standard NACE TM 0177 by tensile test and by four-point bending test. The obtained results have confirmed influence of the used metallurgy of testing on final evaluation of resistance of duplex steels to SSC, as well as influence of microstructural characteristics, which manifested themselves namely by scope of corrosion attack of the samples and by different manner of crack propagation in the matrix.

PL

Artykuł dotyczy wpływu różnych rodzajów obciążeń i zmian mikrostrukturalnych na ocenę odporności stali duplex 22Cr05Ni na siarczkową korozję naprężeniową (SSC). Użyto stali duplex z dwóch wytopów. Każdy z wytopów był oceniany zarówno w stanie bezpośrednio po procesie walcowania i wyżarzania ujednorodniającego, jak i wyżarzonych w warunkach laboratoryjnych (800 oC/5h/powietrze). Mikrostruktura stali w stanie wyjściowym była ferrytyczno-austenityczna, natomiast po wyżarzaniu ferrytyczno-austenityczna z obecnością fazy σ na powierzchni rozdziału faz. Badanie odporności stali duplex przeprowadzono zgodnie z normą NACE TM 0177 wykonując próbę rozciągania oraz próbę zginania 4-punktowego. Uzyskane wyniki potwierdziły zarówno wpływ zastosowanej metody wytwarzania badanego materiału na końcową ocenę odporności stali duplex na siarczkową korozję naprężeniową (SSC), jak również wpływ zmian strukturalnych, co przejawiało się w zasięgu oddziaływań korodujących w badanych próbkach oraz odmiennym sposobie propagacji pęknięć w osnowie.

2

The evaluation of materials properties of inservice components by small punch tests

Matocha K.

Journal of KONES

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2009

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Vol. 16, No. 4

315-321

EN

Residual lifetimes and/or structural integrity assessments of critical components of mechanical plants and/or steel structures reąuire the knowledge of actual mechanical properties of the components' materials, because the material properties could be reduced throughout a service life by ageing. the use of standardised mechanical test techniques for determination of actual mechanical properties of the components under operation can cause its considerable damage due to size of necessary testing material and following repairs by welding. The need of a large amount of testing material can be eliminated by new advanced testing method based on „ non destructive " sampling of a small amount of testing material from the component surface. the mechanical characteristics are then determined by Small Punch) Tests (SPT). This paper describes the use of this advanced test technique for determination of tensile properties and fracture characteristics (FATT, J IC) of materials. The small punch test technique provides at present time a vehicle for determination of actual tensile and fracture properties necessary for optimisation of operating procedures and inspection intervals as well as for repairs strategies and residual lifetime assessment.

3

Determination of actual tensile and fracture properties of steam turbine rotor by small punch tests

Matocha K., Purmensky J., Mišcicki M.

Advances in Materials Science

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2007

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Vol. 7, nr 2(12)

32-39

EN

The paper summarizes the determination of tensile properties (Yield Stress, Tensile Strength) and fracture characteristics (FATT, fracture toughness JIC) by Small Punch (SP) tests of material samples taken from regulation stage No1 and regula-tion stage Nol9 of steam turbine rotor of 13UCK60 w Ec IV turbine in Łodž Power Plant by Rolls-Royce SSamTM-2 scoop sampling machine.

4

Vliv velikostí zkušebního tělesa na hodnotu vrubové houževnatosti

Matucha P., Matocha K., Strnadel B.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2004

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z. 78

109-112

5

The influence of water environment on fatigue crack growth behaviour of high strength low alloy steel.

Matocha K.

Inżynieria Materiałowa

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2001

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R. XXII, nr 5

617-619

EN

The effect of loading frequency (0,1-10 Hz) and temperature (4-75 degrees centigrade) on fatigue crack growth behaviour in water environment were studied on low alloy high strength steel of grade 38MnSiCr2Ni2Mo. Fatigue crack growth rates in distilled water increased significantly compared with these in air for loading frequency lower or equal than 1 Hz. Besides the loading frequency the kinetics of fatigue crack growth in studied steel is strongly influenced by delta K and water temperature.