The Effect of Carbon Diffusion on Creep Behaviours for a Dissimilar Joint Between P91 and 12Cr1MoV Steels

2016 ◽  
Author(s):  
Yanping Zhao ◽  
Jianming Gong ◽  
Yong Jiang
Keyword(s):  
Power Law ◽  
Threshold Stress ◽  
Carbon Diffusion ◽  
Dissimilar Joint ◽  
Multiphase Model ◽  
High Alloy ◽  
Dissimilar Joints ◽  
Premature Failure ◽  
Creep Properties ◽  
Alloy Part

Dissimilar joints have been widely used in many applications, especially for steam piping in the superheater and reheater of power plants. However, these dissimilar metal welds tend to fail less than half of their design life, and carbon diffusion is the main cause of the premature failure. Dissimilar joints operated at high temperature or after post-weld heat treatment (PWHT) exhibit carbon-enriched zone (CEZ) in the high alloy part and carbon-depleted zone (CDZ) in the low alloy part, causing by the chemical potential gradients across the weld interface. The carbides dissolute in the low alloy part while precipitate in the high alloy part. At the same time, a consequent of strength gradients are generated between the CEZ and CDE. The CDZ results in a loss of creep strength due to the carbides dissolution while an increase of strength due to the carbides precipitation. In this work, welding consumable of GTR-2CM was used to join P91 and 12Cr1MoV metals together. The stable phases and carbon activities of these metals are calculated by THERMO-CALC software. Carbon diffusion between P91/GTR-2CM/12Cr1MoV dissimilar joint after aging at 550 °C for varying time are predicted by employing dispersed multiphase model in DICTRA software. Volume fractions of carbides varying with distance from both sides of the weld interfaces were also investigated, showing that the formation of CDZs and CEZs is related to the dissolution and precipitation of M23C6 and M7C3 carbides. The dissolution and coarsening of M7C3 and M23C6 particles in the CDZ and CEZ were also modelled by DICTRA software. The creep properties of base metals, weld metal and the dissimilar joint were investigated at 550 °C. The stress dependence of minimum creep rate and rupture life obeyed the Norton’s power law, and the stress exponents can be used to identify the creep mechanism. Monkman-Grant (MG) relations were also used to study the creep rupture data. The simulation results of carbon diffusion can be used to study the creep properties of CDZ and CEZ for the P91/GTR-2CM/12Cr1MoV dissimilar joint. The threshold stress concept can be incorporated into the analysis of creep power law. The magnitudes of threshold stress within CEZ and CDZ can be calculated according to the volume fraction and average diameter of carbides from carbon diffusion.

EASTERN STAINLESS TYPE 309S

Alloy Digest ◽  
1984 ◽  
Vol 33 (3) ◽  
Keyword(s):  
Stainless Steel ◽  
Heat Exchangers ◽  
Elevated Temperatures ◽  
Heat Treating ◽  
Scaling Up ◽  
Oil Refining ◽  
Steel Company ◽  
High Alloy ◽  
Creep Properties ◽  
Refining Equipment

Abstract EASTERN STAINLESS TYPE 309S is a heat-resisting grade of stainless steel. Because of its high alloy content, it resists scaling up to 2000 F. It also has good tensile and creep properties and elevated temperatures. Type 309S has good ductility and malleability; therefore, difficult shapes and structures can be fabricated easily and it can be machined readily. It can be welded easily and gives strong, ductile welds. Some of its many applications are annealing boxes, boiler baffles, dryers, furnace parts, heat exchangers and oil-refining equipment. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-441. Producer or source: Eastern Stainless Steel Company.

scholarly journals Temperature Resistance of Mo3Si: Phase Stability, Microhardness, and Creep Properties

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 564 ◽  
Author(s):  
Olha Kauss ◽  
Susanne Obert ◽  
Iurii Bogomol ◽  
Thomas Wablat ◽  
Nils Siemensmeyer ◽  
...  
Keyword(s):  
Power Law ◽  
Phase Stability ◽  
Gas Turbines ◽  
Constitutive Models ◽  
Creep Properties ◽  
Multi Scale ◽  
Scale Modeling ◽  
Significant Difference ◽  
Before And After ◽  
Multi Phase

Mo-Si-B alloys are one of the most promising candidates to substitute Ni based superalloys in gas turbines. The optimization of their composition can be achieved more effectively using multi-scale modeling of materials behavior and structural analysis of components for understanding, predicting, and screening properties of new alloys. Nevertheless, this approach is dependent on data on the properties of the single phases in these alloys. The focus of this investigation is Mo3Si, one of the phases in typical Mo-Si-B alloys. The effect of 100 h annealing at 1600 °C on phase stability and microhardness of its three near-stoichiometric compositions—Mo-23Si, Mo-24Si and Mo-25Si (at %)—is reported. While Mo-23Si specimen consist only of Mo3Si before and after annealing, Mo-24Si and Mo-25Si comprise Mo5Si3 and Mo3Si before annealing. The latter is then increased by the annealing. No significant difference in microhardness was detected between the different compositions as well as after annealing. The creep properties of Mo3Si are described at 1093 °C and 1300 °C at varying stress levels as well as at 300 MPa and temperatures between 1050 °C and 1350 °C. Three constitutive models were used for regression of experimental results—(i) power law with a constant creep exponent, (ii) stress range dependent law, and (iii) power law with a temperature-dependent creep exponent. It is confirmed that Mo3Si has a higher creep resistance than Moss and multi-phase Mo-Si-B alloys, but a lower creep strength as compared to Mo5SiB2.

scholarly journals Mechanical properties and microstructural characteristics of rotary friction welded dissimilar joints of rolled homogeneous armor steel and medium carbon steel

2021 ◽  
Vol 30 (1) ◽  
pp. 171-178
Author(s):  
K. Karthick ◽  
S. Malarvizhi ◽  
V. Balasubramanian
Keyword(s):  
Carbon Steel ◽  
Arc Welding ◽  
Medium Carbon Steel ◽  
Dissimilar Joint ◽  
Microstructural Characteristics ◽  
Dissimilar Joints ◽  
Medium Carbon ◽  
Metal Arc Welding ◽  
Armor Steel ◽  
Welding Processes

Abstract Distinct materials are used for the construction of battle tanks used in defense sectors. The hull and turret of the battle tanks are made up of rolled homogeneous armor steel (also known as armor steel). The inner portions like the driver cabin and control room are covered with medium carbon steel. Hence, the dissimilar joint between these materials is unavoidable in the battle tank construction. Conventional fusion welding processes like manual metal arc welding, gas metal arc welding, and gas tungsten arc welding are preferred to join the dissimilar metals. However, the high heat input nature of these processes will create hydrogen induced cracking, high residual tensile strain, and HAZ softening, etc. To minimize these issues, solid state welding processes were adopted. In the present study, mechanical properties and microstructural characteristics of rotary friction welded dissimilar joint of armor steel and medium carbon steel was analyzed. The ultimate tensile strength of the dissimilar joint is around 775 MPa and the failure occurred at the medium carbon steel side. The impact toughness value of dissimilar joints is higher than medium carbon steel and lower than armor steel. The microstructure across the dissimilar joint has distinct features and a complex pattern was observed at the weld interface.

Decisive impact of Filler-free joining processes on the Microstructural evolution, tensile and impact properties of 9Cr-1Mo-V-Nb to 316 L(N) dissimilar joints

2021 ◽  
pp. 095440622110293
Author(s):  
A Venkatakrishna ◽  
AK Lakshminarayanan ◽  
P Vasantharaja ◽  
M Vasudevan
Keyword(s):  
Weld Metal ◽  
Laser Beam Welding ◽  
Carbon Diffusion ◽  
Comparative Investigation ◽  
Impact Testing ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Dissimilar Weld ◽  
Transverse Tensile ◽  
Welding Processes

Filler-free (FF) welding processes namely, Activated Tungsten Inert Gas welding (ATIG), Laser Beam Welding (LBW), and Friction Stir Welding (FSW) were utilized for joining the nuclear grade 9Cr-1Mo-V-Nb ferritic-martensitic steel and 316 L(N) austenitic stainless steel. A comparative investigation was made by assessing the weld geometries, metallurgical features, material mixing proportions, carbon diffusion behaviour, and mechanical properties of the post-weld heat-treated (PWHT) dissimilar weld joints. Geometries of the weld zones were observed with the transverse and longitudinal macrographs. Metallurgical features were examined by optical microscopy (OM) and Scanning electron microscopy (SEM). Three-phase microstructures were identified in the dissimilar weld zones (DWZ). The elemental distributions were identified by Energy-dispersive X-ray spectroscopy (EDAX). The mixing proportions of the dissimilar alloys and the formation of δ-ferrite in the dissimilar heat-affected zones (HAZ) and DWZ were analytically quantified. Moreover, the diffusion activity of carbides/interstitial carbon atoms was examined by Secondary ion mass spectroscopy (SIMS). In the FSW joints, the intermingled microstructures are recorded with high and stabilized hardness values as compared to the DWZ of the ATIG and LBW joints. In the transverse tensile test, all FF joints were failed at the 316 L(N) base metal (BM) region. Tensile and impact testing of all weld metal indicated that, the weld metal region of the LBW joint exhibited higher strength and lower toughness as compared to the ATIG and FSW joints. The presence of untransformed, recrystallized fine equiaxed austenite along and refined martensitic structure arranged in an alternate layers within the weld metal region of FSW joint caused the higher toughness property than the ATIG and LBW joints.

Creep Deformation of Dispersion Strengthened NiAl and TiAl Intermetallics

1990 ◽  
Vol 213 ◽  
Author(s):  
K. Sadananda ◽  
H. Jones ◽  
C.R. Feng ◽  
A.K. Vasudevan
Keyword(s):  
Melting Point ◽  
Power Law ◽  
Creep Deformation ◽  
Tensile Creep ◽  
High Melting ◽  
High Melting Point ◽  
Initial Value ◽  
Creep Properties ◽  
Specific Strength ◽  
Power Law Creep

ABSTRACTIn this study, the creep properties of two intermetallics; NiAl and TiAl have been evaluated. The former was selected based on its relatively high melting point, and the latter was based on its specific strength and high melting point. Tensile creep deformation rates in range of 760 to 930°C were determined as a function of stress for both monolithic NiAl, NiAl reinforced with HfC dispersoids and TiAl reinforced with TiB2 dispersoid. Microstructure and dislocation structures were examined both beore and after creep in both alloys to identify the creep mechanisms. In both systems, deformation occurs by power-law creep with diffusion controlling creep rate. Power-law breakdown regimes have been identified for both systems. In addition, TiAl undergoes dynamic recrystallization during creep resulting in smaller grain sizes than the initial value.

Microstructure and Mechanical Properties of Dissimilar Joints of AZ31 MG Alloy to Aluminium Alloys

2010 ◽  
Vol 638-642 ◽  
pp. 214-219 ◽  
Author(s):  
Woong Seong Chang ◽  
Heung Ju Kim ◽  
Sung Wook Kim
Keyword(s):  
Tensile Strength ◽  
Base Metal ◽  
Travel Speed ◽  
Mg Alloy ◽  
Dissimilar Joint ◽  
Al Alloy ◽  
Magnetic Pulse ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Az31 Mg Alloy

In attempts to improve the performance of dissimilar joints between AZ31 Mg alloy and different Al alloys, solid state joining processes such as Magnetic Pulse Welding (MPW) and Friction Stir Welding (FSW) were applied for minimizing the formation of brittle intermetallic phases. MPW process has been concentrated mainly on round section tube to tube and tube to bar welds. Mg alloy AZ31 has been successfully welded to pure Al A1070 as well as to Al alloy A3003. Tensile test clearly showed the MPW welds were stronger than the weaker of the base metal so failure occurred in aluminum base metal. While FSW process for the dissimilar joint between AZ31B/A6061 alloys with a thickness of 2mm revealed optimum weldability under the conditions of travel speed of 0.8mm/sec and tool rotation speed of 850rpm. For the sound dissimilar joint, the maximum tensile strength of 179 MPa, which was about 80 % of the Mg base metal tensile strength, has been obtained.

scholarly journals The effect of material position of multi-pass friction stir processing on friction stir welded AA1050/AA6082 dissimilar joints

2021 ◽  
Vol 309 ◽  
pp. 01001
Author(s):  
Oritonda Muribwathoho ◽  
Velaphi Msomi ◽  
Ali Merdji ◽  
Sipokazi Mabuwa
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Friction Stir Welding ◽  
Friction Stir Processing ◽  
Vickers Microhardness ◽  
Microstructural Analysis ◽  
Dissimilar Joint ◽  
Dissimilar Joints ◽  
Friction Stir ◽  
Number Of Passes

The AA1050 and AA6082 plates were used in producing dissimilar joint through friction stir welding (FSW) technique. The developed dissimilar joint was then subjected to multi-pass friction stir processing (FSP) technique. Various tests for the AA1050/AA6082 (AA1050 on the advancing side) and AA6082/AA1050 (AA6082 on the advancing side) joints were conducted on joints subjected to 1pass (1P) and 4pass (4P). The microstructural analysis showed that the increase in number of FSP passes resulted in a reduced grain size regardless of the of material position. The Vickers microhardness for AA1050/AA6082 FSPed joints increased towards AA6082 side while the microhardness for AA6082/AA1050 FSPed joints decreased towards the AA 1050 side regardless the number of the passes. The ultimate tensile strength (UTS) of AA1050/AA6082 joint increased with an increase in the number of passes while AA6082/AA1050 fluctuated between the specimens sampled from different locations of the FSPed joints.

Sign in / Sign up

Export Citation Format

Share Document