Effect of heat treatment on structure and mechanical properties of 12Cr-3Co steel with low N and high B contents

Published on Nov 19, 2019
· DOI :10.1063/1.5132109
Ivan Nikitin2
Estimated H-index: 2
,
Alexandra Fedoseeva10
Estimated H-index: 10
+ 1 AuthorsRustam Kaibyshev58
Estimated H-index: 58
Source
Abstract
The effect of heat treatment on the microstructure and mechanical properties of Febal-0.1 wt.%C-12Cr-3Co-2.5W-1Cu-VNbTaBN steel was investigated. After normalization in the range of 1050-1150°C, the martensitic structure was dominant; δ-ferrite content was about 10%. When the temperature of normalizing increased from 1050°C to 1150°C, the average size of prior austenite grains increased from 44 to 68 µm. After tempering at 750, 770 and 800°C, tempered martensitic lath structure with a high dislocation density within martensitic laths contained nanosized M23C6 carbides along the boundaries of prior austenite grains and laths and (Ta,Nb)X carbonitrides randomly distributed in the ferritic matrix. The average sizes of M23C6 carbides and (Ta,Nb)X carbonitrides were about 50 nm and 40 nm, respectively, regardless of tempering temperature. The M6C carbide particles were also observed along the boundaries of prior austenite grains and pockets as well as along the boundaries between δ-ferrite and martensite; their amount was negligible. When tempering temperature increased from 750 to 800°C, the particle density on the boundaries between δ- ferrite/martensite decreased from 3.8 to 0.2 µm-1. A relationship between the lath size (h) and the density of free dislocations (ρ) can be described as h = (5.41/√ρ) - 0.07. Increasing the tempering temperature to 800°C led to a decrease in the hardness up to ∼220 HB, yield stress and ultimate tensile stress up to 520 and 700 MPa, respectively.The effect of heat treatment on the microstructure and mechanical properties of Febal-0.1 wt.%C-12Cr-3Co-2.5W-1Cu-VNbTaBN steel was investigated. After normalization in the range of 1050-1150°C, the martensitic structure was dominant; δ-ferrite content was about 10%. When the temperature of normalizing increased from 1050°C to 1150°C, the average size of prior austenite grains increased from 44 to 68 µm. After tempering at 750, 770 and 800°C, tempered martensitic lath structure with a high dislocation density within martensitic laths contained nanosized M23C6 carbides along the boundaries of prior austenite grains and laths and (Ta,Nb)X carbonitrides randomly distributed in the ferritic matrix. The average sizes of M23C6 carbides and (Ta,Nb)X carbonitrides were about 50 nm and 40 nm, respectively, regardless of tempering temperature. The M6C carbide particles were also observed along the boundaries of prior austenite grains and pockets as well as along the boundaries between δ-ferrite and martensite; thei...
📖 Papers frequently viewed together
3 Citations
11 Citations
References8
Newest
#1Alexandra FedoseevaH-Index: 10
#2Nadezhda DudovaH-Index: 13
Last. Andrey BelyakovH-Index: 41
view all 4 authors...
The effect of increasing tungsten content from 2 to 3 wt % on the creep rupture strength of a 3 wt % Co-modified P92-type steel was studied. Creep tests were carried out at a temperature of 650 °C under applied stresses ranging from 100 to 220 MPa with a step of 20 MPa. It was found that an increase in W content from 2 to 3 wt % resulted in a +15% and +14% increase in the creep rupture strength in the short-term region (up to 103 h) and long-term one (up to 104 h), respectively. On the other han...
17 CitationsSource
#1Valeriy Dudko (Belgorod State University)H-Index: 9
#2Alexandra Fedoseeva (Belgorod State University)H-Index: 10
Last. Rustam Kaibyshev (Belgorod State University)H-Index: 58
view all 3 authors...
Abstract The mechanical behavior of a P92-type steel was studied by tension and Charpy impact tests in the temperature range of 77–293 K. The yield stress (YS) and uniform elongation increase concurrently with decreasing temperature because the steel exhibits work-hardening behavior. Transgranular dimpled fracturing remains the primary fracture mechanism under tension down to 193 K. Brittle fracture takes place at lower temperatures. At 77 K, the steel exhibits a well-defined yield plateau. Impa...
11 CitationsSource
#1Hilmar Kjartansson Danielsen (DTU: Technical University of Denmark)H-Index: 18
For high temperature applications, 9–12 wt-%Cr steels in fossil fired power plants rely upon precipitate strengthening from (V,Nb)N MX nitrides for long term creep strength. During prolonged exposure at service temperature, another nitride precipitates: Cr(V,Nb)N Z phase. The Z phases lowly replace MX, eventually causing a breakdown in creep strength. The present paper reviews the Z phase and its behaviour in 9–12 wt-%Cr steels including thermodynamic modelling, crystal structure, nucleation pro...
34 CitationsSource
#1Valeriy Dudko (Belgorod State University)H-Index: 9
#2Alexandra Fedoseeva (Belgorod State University)H-Index: 10
Last. Rustam Kaibyshev (Belgorod State University)H-Index: 58
view all 4 authors...
The deformation behavior and the microstructure evolution under the creep of 10Kh9V2MFBR steel (Russian analog of the P92 steel) (in wt %, Fe–8.9% Cr–0.05% Si–0.2% Mn–1.9% W–0.5% Mo–0.25% V–0.07Nb–0.08% N–0.01% B) with the standard (0.1%) and lowered (0.018%) carbon contents have been investigated. After the heat treatment, which included normalizing at 1050°C and tempering at 720–750°C, carbides M 23 C 6 and carbonitrides M(C,N) are formed in the 10Kh9V2MFBR steel, while in the 02Kh9V2MFBR stee...
14 CitationsSource
#1Paul D. JablonskiH-Index: 16
Last. Philip J. Maziasz (ORNL: Oak Ridge National Laboratory)H-Index: 47
view all 4 authors...
The high-temperature components within conventional supercritical coal-fired power plants are manufactured from ferritic/martensitic steels. To reduce greenhouse-gas emissions, the efficiency of pulverized coal steam power plants must be increased to as high a temperature and pressure as feasible. The proposed steam temperature in the DOE/NETL Advanced Ultra Supercritical power plant is high enough (760°C) that ferritic/martensitic steels will not work for the majority of high-temperature compon...
53 CitationsSource
Abstract The effect of boron on creep deformation behavior and microstructure evolution during creep has been investigated for a tempered martensitic 9Cr-3W-3Co-VNb steel containing boron up to 140 ppm at 650°C (923 K) with the emphasis on long term behavior. Creep tests were carried out at 650°C for up to about 70 000 h. The base steel without boron exhibits degradation in creep rupture strength after times above about 1000 h. The addition of boron retards the onset of tertiary or acceleration ...
29 CitationsSource
#1Fujio AbeH-Index: 52
#2Torsten-Ulf KernH-Index: 1
Last. Ramaswamy ViswanathanH-Index: 4
view all 3 authors...
Part 1 General: Introduction The development of creep-resistant steels Specifications for creep-resistant steels: Europe Specifications for creep-resistant steels Production of creep-resistant steels for turbines. Part 2 Behaviour of creep-resistant steels: Physical and elastic behaviour of creep-resistant steels Diffusion behaviour of creep-resistant steels Fundamental aspects of creep deformation and deformation mechanism map Strengthening mechanisms in steel for creep and creep rupture Precip...
191 CitationsSource
#1Toshiaki Horiuchi (National Institute for Materials Science)H-Index: 7
#2Masaaki Igarashi (Sumitomo Metal Industries)H-Index: 16
Last. Fujio Abe (National Institute for Materials Science)H-Index: 52
view all 3 authors...
For the construction of ultra super critical (USC) power plant, 9Cr-3W base ferritic heat-resistant steels with relatively high B and no N have been investigated. Authors have been revealed in the previous report that the addition of 139ppm B significantly improves creep strength of the steels, whereas most of added B forms unidentified borides, which are deemed almost ineffective to creep strength. The effect of improved heat treatment on creep strength and distribution of B in precipitates is ...
96 CitationsSource
Cited By0
Newest