Microstructure and properties of Co3W2 heat-resistant steel by vacuum electron beam welding

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040058
Author(s):  
Youyi Zhang ◽  
Guoqing Gou
Keyword(s):  
Tensile Strength ◽  
Electron Beam ◽  
High Temperature ◽  
Weld Metal ◽  
Base Metal ◽  
Electron Beam Welding ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
The Impact

12Cr10Co3W2MoNiVNbNB (Co3W2) is a new type of martensitic heat-resistant steel, which is mainly used in high-temperature dynamic, static blades, high-temperature bolts and other components of ultra-supercritical steam turbines. The Co3W2 steel was joined by vacuum electron beam welding, and the microstructures of the joints were analyzed. The hardness, tensile strength and impact toughness of the joints were investigated. The results show that the joints mainly consist of weld metal, fusion-line, heat-affected zone (HAZ) and base metal, the microstructure of the weld metal is a coarse martensite. The hardness of the weld metal is about 326 HV higher than that of the base metal, and the tensile strength of the joints is 939 MPa, which can reach 98.63% of base metal. The impact absorbed energy of weld metal is such that the weakest part of the welded joints during the impact process is about 18.5 J.

Rupture Behavior of Multi-Pass Welded Joints of Heat Resistant Steel Subjected to Creep Loading

2007 ◽  
Author(s):  
Masayoshi Yamazaki ◽  
Hiromichi Hongo ◽  
Takashi Watanabe
Keyword(s):  
Weld Metal ◽  
Base Metal ◽  
Welded Joints ◽  
Stress Condition ◽  
Welded Joint ◽  
Creep Rupture ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Type Iv

By Conducting long-term creep rupture tests for ferritic (2.25Cr-1Mo and 9Cr-1Mo-VNb) and austenitic (18Cr-8Ni and 16Cr-12Ni-2Mo-0.01C-0.07N) heat resistant steel multi-pass welded joints, creep rupture behavior and microstructures were examined. Constant-load creep rupture tests were conducted at 550 and 600 °C up to about 30,000h. Viewpoint in this study was centered on the influence of microstructure on the fracture location of welded joints in heat resistant steels. The results obtained are as follows; 1. The rupture location of the welded joint in austenitic heat resistant steel was found to shift from the base metal at the higher stress condition to the weld metal at lower stress condition at 550 and 600 °C. 2. In the welded joint of austenitic heat resistant steels, the last layer of weld metal showed considerably lager creep strain than the central layers of weld metal. 3. The rupture location of the welded joint in ferritic heat resistant steel was found to shift from the base metal or weld metal at the higher stress condition to the fine-grained HAZ adjacent to the base metal at lower stress condition at 550 and 600 °C. 4. Type IV creep crack initiation occurred in the fine grained HAZ region adjacent to the base metal for the weld metal pass overlap regions of multi-pass large welded joints specimen in 2.25Cr-1Mo steel. 5. Type IV creep crack of the 9Cr-1Mo-V-Nb welded joint nucleated in the curved part of the groove angle and propagated to the top part of the V-groove. It was found that the voids and cracks were initiated inside the plate thickness.

scholarly journals Microstructure and Mechanical Properties of an Austenitic Heat-Resistant Steel after Service at 570 °C and 25.4 MPa for 18 Years

2021 ◽  
Author(s):  
Xu Yang ◽  
Chengwei Yu ◽  
Xisheng Yang ◽  
Kai Yan ◽  
Gong Qian ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Power Plant ◽  
Impact Toughness ◽  
Grain Boundary ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Microstructure And Mechanical Properties ◽  
The Impact

AbstractMicrostructure and mechanical properties of an austenitic heat-resistant steel (12Cr18Ni12Ti) serviced in a supercritical power plant at 570 °C/25.4 MPa for 160,000 h were investigated. The results show that the hardness and the tensile strength did not decrease; however, the impact toughness was remarkably reduced. The TiC precipitate shows excellent thermostability; for example, it hardly grew up, and no big M23C6 carbides were found. However, large Fe, Cr-rich σ-phase was doomed to precipitate along grain boundary, which should be responsible for the reduced toughness. The growth of σ-phase was observed to have an interaction with the preexisted carbides.

Study on the High Temperature Creep Behavior of 30Cr25Ni20 Heat-Resistant Steel

2019 ◽  
Vol 814 ◽  
pp. 157-162
Author(s):  
You Yang ◽  
Xiao Dong Wang ◽  
Wei Feng Tang
Keyword(s):  
High Temperature ◽  
Internal Structure ◽  
Creep Strain ◽  
High Temperature Creep ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Creep Fracture ◽  
Heat Resistant ◽  
Temperature Creep ◽  
Before And After

The high temperature creep test of heat-resisting steel 30Cr25Ni20 for automobile exhaust manifolds was carried out, and the creep strain-time curves at 650°C and 700°C in the different loads were obtained. The effects of different creep temperature and stress on creep life of materials were studied. The microstructure of the fracture after creep was observed by scanning electron microscopy. Microstructures before and after creep at different temperatures were compared by optical microscopy. The results show that the creep fracture life of heat-resistant steel decreases with the increase of stress at the same temperature. The creep fracture life decreases with the increase of temperature at the same stress, too. The fracture of heat-resistant steel shows good high temperature plasticity and a ductile fracture after creep. The fracture dimples become deeper with the increase of stress. At 650°Cand 700°C, the stress exponent is 8.6 and 6, respectively. When the sample was subjected to high temperature creep at 700°C, the precipitates increase obviously and the reticular structure became very large. At this point, the internal structure of the material is destroyed, and the matrix structure becomes unevenly distributed. The failure of the internal structure leads to the dramatic increase of the creep strain, and the failure of the internal structure will be more serious with the deformation of the sample.

scholarly journals PM-08Microstructure analysis of MX precipitates in weld metal for heat resistant steel

Microscopy ◽  
2018 ◽  
Vol 67 (suppl_2) ◽  
pp. i39-i39
Author(s):  
Hiroya Yasui ◽  
Kouichi Shida ◽  
Shinji Takahashi ◽  
Toshiaki Okabe ◽  
Hiroyuki Takeda ◽  
...  
Keyword(s):  
Weld Metal ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Heat Resistant

Experiment Study on Cutter Disrepair Principle and Optimization for Machining Heat-Resistant Steel

2012 ◽  
Vol 500 ◽  
pp. 58-64
Author(s):  
Yao Nan Cheng ◽  
Xian Li Liu ◽  
Fu Gang Yan ◽  
Zhen Jia Li ◽  
Xian Zhou Wang
Keyword(s):  
Mathematic Model ◽  
Resistant Steel ◽  
Experiment Study ◽  
Premature Failure ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
Design Production ◽  
Milling Temperature ◽  
The Difference ◽  
The Impact

In order to find out the cutter disrepair principle and provide a valuable reference for the design, production and use of the heavy-duty hard alloy cutter, have experiment study on machining the heat-resistant steel-the 3Cr-1Mo-1/4Vsteel. First, have impact disrepair experiments with several types of different grooves milling inserts, and find out the difference of the impact disrepair invalidation types among them, and build the impact disrepair life cumulating distribution function mathematic model. Second, based on the adhering disrepair experiments, find out the difference of the adhering disrepair invalidation types, build the quantitative mathematic relation between milling temperature and maximal adhering disrepair depth on rake face of the cutter, and analyze the rule that the milling temperature affects the adhering disrepair. And then, on the basis of the scene machining, have analysis on cutter disrepair phenomenon and mechanism under the joint action of force and heat, so to provide a theoretical basis on how to avoid premature failure of the tool for the actual production process.

High-Temperature Oxidation Behaviors of 30Cr25Ni20Si Heat-Resistant Steel in Air

2020 ◽  
Vol 861 ◽  
pp. 83-88
Author(s):  
You Yang ◽  
Xiao Dong Wang
Keyword(s):  
High Temperature ◽  
Oxide Film ◽  
High Temperature Oxidation ◽  
Film Growth ◽  
Surface Oxidation ◽  
Mass Gain ◽  
Resistant Steel ◽  
Temperature Oxidation ◽  
Heat Resistant Steel ◽  
Heat Resistant

High temperature oxidation dynamic behaviors and mechanisms for 30Cr25Ni20Si heat-resistant steel were investigated at 800, 900 and 1000°C. The oxide layers were characterized by scanning electron microscopy (SEM-EDS), X-ray diffractometer (XRD). The results showed that the oxidation rate of test alloys is increased with increasing the oxidation time. The oxidation dynamic curves at 800 and 900°C follow from liner to parabolic oxidation law. The transition point is 10 h. At 1000°C, the steel exhibits a catastrophic oxidation, and the oxidation mass gain value at 50 h is 0.77 mg/cm2. This suggests that the steel at 900°C has formed a dense protective surface oxidation film, effectively preventing the diffusion of the oxygen atoms and other corrosive gas into the alloy. Therefore, at the first stage of oxidation, chemical adsorption and reaction determine the oxide film composition and formation process. At the oxide film growth stage, oxidation is controlled by migration of ions or electrons across the oxide film. When the spinel scale forms, it acts as a compact barrier for O element and improving the oxidation resistance.

scholarly journals Properties of High Temperature Oxidation of Heat-resistant Steel with Aluminium and Copper

2019 ◽  
Vol 25 (4) ◽  
pp. 394-400
Author(s):  
Hong LI ◽  
Chengzhi ZHAO ◽  
Tao YAN ◽  
Chao DING ◽  
Hexin ZHANG ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxide Films ◽  
Main Element ◽  
Resistant Steel ◽  
Temperature Oxidation ◽  
Heat Resistant Steel ◽  
X Ray ◽  
Heat Resistant ◽  
Test Steel

The research is focused on a novel aluminum and copper-containing heat-resistant steel. The steel was designed by the material performance simulation software JmatPro, performed high-temperature oxidation tests at 650 °C and 700 °C atmospheric conditions, and analyzed the high-temperature oxidation processes and its mechanisms.The phase transtions and surface morphology of the oxide films were studied using X-ray diffraction (XRD), electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The results showed that the equilibrium phase of the test steel is composed of γ phase and δ phase at 1050 °C and tranforms to tempered martensite and δ-Fe mixed structure after heat treatment. The preferential oxidation of Fe and Cr and the internal oxidation of Al occurred during the high temperature oxidation of the test steel. The oxide films were formed with various shape and weak bonding properties after high-temperature oxidation at 650℃. To the contrary, the oxide films more regular and evenly distributed, and has a certain protective effect after high-temperature oxidation at 700 ℃. The oxide films were divided into two layers, Fe2O3 is main element in the outer layer, the inner layer is mainly consisting the oxide of Cr. However, the addition of Cu element can promote the diffusion of Al and Si elements, which is beneficial to the formation of Al2O3 and SiO2 protective oxide films and excellent in high temperature oxidation resistance.

Quench Brittleness of 12%Cr Martensitic Heat-Resistant Steel

2011 ◽  
Vol 479 ◽  
pp. 8-12 ◽  
Author(s):  
Gang Yang ◽  
Zheng Dong Liu ◽  
Shi Chang Cheng ◽  
Mu Xin Yang
Keyword(s):  
Impact Toughness ◽  
Cooling Rate ◽  
Microstructural Characterization ◽  
Temper Brittleness ◽  
Resistant Steel ◽  
Slow Cooling ◽  
Continuous Precipitation ◽  
Heat Resistant Steel ◽  
Heat Resistant ◽  
The Impact

The mechanism of brittleness due to slow cooling during quenching was experimentally investigated in 12% Cr martensitic heat resistant steel. The mechanical property tests and microstructural characterization by SEM、TEM and XRD were conducted. The results showed the impact toughness would decrease with the slowing of cooling rate during quenching, and the low cooling rate within the temperature range from 820 to 660 °C played a significant effect on the impact toughness . Different from the mechanism of temper brittleness, the main causes of embrittlement due to the slow cooling upon quenching were both the continuous precipitation of M23C6 along prior austenite grain boundaries during the process of slow cooling and that of M2C along prior residual austenite film during tempering, and this kind of quench brittleness was nonreversal.

Sign in / Sign up

Export Citation Format

Share Document