Influence of Microstructure and Heat-Treatment on Impact and Creep Properties of a Low Alloy CrMoV Turbine Steel

1967 ◽  
Vol 89 (2) ◽  
pp. 238-246 ◽  
Author(s):  
K. Relander ◽  
T. Geiger
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Lower Bainite ◽  
Mechanical Tests ◽  
Creep Ductility ◽  
Creep Properties ◽  
Microstructural Effects ◽  
Turbine Steel ◽  
Vanadium Carbides ◽  
The Impact

This investigation concerns the strongly scattering mechanical properties of a 17 MoV 84 creep resistant steel. Emphasis is laid on the effect on microstructure of heat-treatment. The mechanical tests made after various austenitizing treatments, cooling rates, and tempering temperatures revealed that a complex relationship existed between the mechanical properties and microstructure in the steel precipitation hardened by vanadium carbides. In spite of constant tensile strength, the impact and creep properties in the steel therefore differ widely, due to relatively small microstructural effects. The study shows that the microstructural constituents, i.e., martensite, lower bainite, upper bainite in aciculare and globulare forms, as well as pre-eutectoid ferrite, all influence the room temperature ductility in a similar way to the creep ductility. However, in the case of creep strength, similar microstructural constituents have almost the reverse effect. As a result of these contrasting effects, it is not possible to obtain good ductility and creep properties at the same time. Any heat-treatments recommended can therefore only be a compromise between the properties desired.

The Effect of Aging Heat Treatment on the Microstructure and Mechanical Properties of 10Cr20Ni25Mo1.5NbN Austenitic Steel

2016 ◽  
Vol 35 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Zhiyuan Liang ◽  
Wanhua Sha ◽  
Qinxin Zhao ◽  
Chongbin Wang ◽  
Jianyong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Heat Treatment ◽  
Austenitic Steel ◽  
Treatment Time ◽  
Aging Treatment ◽  
Secondary Phases ◽  
Aging Heat Treatment ◽  
Microstructure And Mechanical Properties ◽  
The Impact

AbstractThe effect of aging heat treatment on the microstructure and mechanical properties of 10Cr20Ni25Mo1.5NbN austenitic steel was investigated in this article. The microstructure was characterized by scanning electron microscopy, energy dispersive spectrometry and transmission electron microscopy. Results show that the microstructure of 10Cr20Ni25Mo1.5NbN austenitic is composed of austenite. This steel was strengthened by precipitates of secondary phases that were mainly M23C6 carbides and NbCrN nitrides. As aging treatment time increased, the tensile strength first rose (0–3,000 h) and then fell (3,000–5,000 h) due to the decrease of high density of dislocations. The impact absorbed energy decreased sharply, causing the sulfides to precipitate at the grain boundary. Therefore, the content of sulfur should be strictly controlled in the steelmaking process.

Application of Tailored Heat Treated Blanks under Quasi Series Conditions

2007 ◽  
Vol 344 ◽  
pp. 383-390 ◽  
Author(s):  
Marion Merklein ◽  
Uwe Vogt
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Local Heat ◽  
Strength Distribution ◽  
Process Window ◽  
Short Term ◽  
Forming Process ◽  
Heat Treated ◽  
Set Up ◽  
The Impact

Tailored Heat Treated Blanks (THTB) are blanks that exhibit locally different strength specifically optimized for the succeeding forming process. The strength distribution is set by a local, short-term heat treatment modifying the mechanical properties of the material. Hence, THTB allow enhancing forming limits significantly leading to shorter and more robust manufacture process chains. In order to qualify the use of THTB under quasi series conditions, the interdependencies of the blank’s local heat treatment and the entire process chain of the car body manufacture have to be analyzed. In this respect, the impact of a short-term heat treatment on the mechanical properties of AA6181PX, a commonly used aluminum alloy in today’s car bodies, was studied. Also the influence of a short-term heat treatment on the coil lubricant, usually already applied by the material supplier, was given a closer look. Based on these experiments process restrictions for the application of THTB in an industrial automotive environment were derived and a process window for the THTB design was set up. In conclusion, strategies were defined how to enhance the found process boundaries leading to a more robust process window.

Study of Cu Addition on Precipitation Behaviors and Mechanical Properties in AA6082 Al-Mg-Si Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 825-828 ◽  
Author(s):  
Man Jin ◽  
Jing Li ◽  
Guang Jie Shao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Thermal Stability ◽  
Treatment Process ◽  
Mechanical Tests ◽  
Age Hardening ◽  
Heat Treatment Process ◽  
Softening Process

The precipitation behaviors and microstructures of nano-precipitates in AA6082 Al-Mg-Si alloy with and without Cu additions during heat treatment process were studied using hardness measurements, TEM, mechanical tests and 3DAP. Meanwhile, the softening process of 6082 alloys with Cu and without Cu, isothermally conditioned at 250°C, has also been investigated. It was found that the rate of age hardening, mechanical properties and thermal stability are higher for the Cu-containing alloy. The TEM and 3DAP observations showed that Q’ precipitates were existed after aged at 170°C for 8h in the alloy with Cu addition. Comparing the hardness, mechanical properties and thermal stability curves, it was concluded that the Q’ precipitates play a major role in improving the age hardening kinetics and properties of 6082 alloy with Cu addition.

Research on the Flow Characteristics of Polymer Injection Molding under Ultrasonic Vibration and Plastics’ Mechanical Strength

2010 ◽  
Vol 37-38 ◽  
pp. 1092-1100
Author(s):  
Ji Bin Li ◽  
Ke Ke Xu ◽  
Xin Bo Lin ◽  
Xiao Yu Wu ◽  
Guo Li Gao
Keyword(s):  
Mechanical Properties ◽  
Injection Molding ◽  
Ultrasonic Vibration ◽  
Flow Characteristics ◽  
Mechanical Tests ◽  
Impact Testing ◽  
Melt Flow Rate ◽  
Polymer Injection ◽  
Molding Method ◽  
The Impact

In this paper, ultrasonic vibration is adopted and exerted on injection molding in order to improve plastics’ forming ability, and the impact testing is used to analyze different injection parts’ mechanical properties. On the one hand, experiments prove that ultrasonic vibration can increase polymer’s melt flow rate, decrease melt viscosity, and improve injection flowing in mould cavity. On the other hand, the mechanical tests prove that the ultrasonic vibration can improve plastics’ tensile strength, elastic modulus and other mechanical properties. As a result, a weldless ultrasound-assisted injection molding method is recommended.

Influence of the conditions of casting and heat treatment on the structure and mechanical properties of the AlMg10 alloy

2017 ◽  
Vol 1 (83) ◽  
pp. 26-32
Author(s):  
P. Kordas
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Liquid State ◽  
Precipitation Hardening ◽  
Solidification Rate ◽  
Dendritic Structure ◽  
Grain Structure ◽  
Alloy Castings ◽  
Die Castings ◽  
The Impact

Purpose: Assessment of the possibilities of shaping the structure and improvement of mechanical properties of casting from AlMg10 alloy through a selection of casting technology and precipitation hardening. Design/methodology/approach: the work evaluated the impact of casting and heat treatment technology on the mechanical properties and structure of AlMg10 alloy castings. The tests were performed on 200 mm × 100 mm × 25 mm plate castings produced by gravity casting methods for sand and metal moulds and by a liquid state press moulding technology. Castings made with these technologies solidify in substantially different heat- evaporation conditions and exhibit varying degrees of primary structure fragmentation. Metallographic and strength tests were performed on raw castings and after heat treatment. Findings: The changes in the morphology and size of primary crystals and the dispersion of the reinforcing phase according to the casting solidification rate and the precipitation hardening treatment were analyzed. Solidifying castings in the form of sand show a globular structure, whereas in die and press castings, a typically dendritic structure occurs, with the dendritic crystals in pressed castings being much smaller in size than the die castings. In castings which were not heat-treated, the reinforcing phase of Al3Mg2 occurs in interdendritic spaces, and its dispersion increases with the rate of cooling. After supersaturation and ageing treatments, the phase α has a grain structure in all samples. The largest dispersion of reinforcing molecules is characterized by press castings. In a raw state, the highest mechanical properties are shown by castings made in the form of sand and the method of pressing in a liquid state. Heat treatment of AlMg10 alloy castings significantly influences the increase of mechanical indexes in all castings investigated. The highest features of Rm are approx. 330 MPa and A5 above 10% is obtained in castings made by the press method. Research limitations/implications: Particular attention should be paid to the avoidance of the effects of slag inclusion, shrinkage and magnesium oxidation during casting of AlMg10 alloys. In die castings of a plate type, due to own stresses, a significant decrease in mechanical properties occurs. Practical implications: The most advantageous mechanical properties of AlMg10 alloy castings are obtained by using liquid-state pressing technology. In addition, this technology makes it possible to produce thin-walled castings of high dimensional accuracy, high air- tightness, fine grain structure, lack of surface defects and low roughness. Originality/value: The paper presents the possibility of improving the mechanical properties of AlMg10 castings by applying heat treatment. It has been proven that the casting method has a significant effect on the mechanical properties of the castings.

Effect of Heat Treatment Hardness of Al-Cu-Mg-Li-Zr, Al-Mg-Si and and Al-Mg-Zn Alloys-Experimental Correlation Using Factorial DOE and ANOVA Methods

2014 ◽  
Vol 881-883 ◽  
pp. 1317-1329 ◽  
Author(s):  
Mahmoud M. Tash ◽  
Saleh Alkahtani
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cold Work ◽  
Solution Treatment ◽  
Statistical Design ◽  
Aging Treatment ◽  
Fractional Factorial ◽  
Statistical Design Of Experiments ◽  
The Impact ◽  
Zn Alloys

The present study was conducted to investigate the effect of heat treatment on the aging and mechanical behavior of Al-Cu-Mg-Li-Zr , Al-Mg-Si and and Al-Mg-Zn alloys (8090 , 6082 and 7075). The effect of cold work after solution treatment, aging parameters (time and temperature) on the microstructure and mechanical properties were studied. Attempts are made to determine the combined effect of cold work and aging treatment on the hardness, UTS and microstructure for these alloys. By study the impact of different heat treatments for Al-Mg-Si alloys (6082), Al-Cu-Mg-Li-Zr (8090) and Al-Mg-Zn (7075) aluminum alloys on the hardness and mechanical properties, it is possible to determine conditions necessary to achieve better mechanical properties and the maximum levels of hardness and values corresponding to those considered suitable for commercial applications of these alloys.Design of Experiment (DOE) method in Minitab is used to measure the impact of various factors and how they relate. Correlation between the hardness and different metallurgical factors for these alloys at both quantitative and qualitative are investigated and analysed. A statistical design of experiments (DOE) approach using fractional factorial design was applied to determine the influence of controlling variables of cold work and heat treatment parameters and any interactions between them on the hardness of the above alloys. A mathematical model is developed to relate the alloy hardness with the different metallurgical parameters to acquire an understanding of the effects of these variables and their interactions on the hardness of wrought Al-alloys. It is noticed that cold work, following solution treatment, accelerates the precipitation rate leading to a rise in strength

Towards improved understanding of PEG-impregnated waterlogged archaeological wood: A model study on recent oak

Holzforschung ◽  
2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Ingela Bjurhager ◽  
Jonas Ljungdahl ◽  
Lennart Wallström ◽  
E. Kristofer Gamstedt ◽  
Lars A. Berglund
Keyword(s):  
Mechanical Properties ◽  
Microfibril Angle ◽  
Mechanical Tests ◽  
Chemical Degradation ◽  
Cellulose Microfibrils ◽  
Radial Compression ◽  
Biological Degradation ◽  
Archaeological Wood ◽  
Waterlogged Archaeological Wood ◽  
The Impact

Abstract To prevent deformation and cracking of waterlogged archaeological wood, polyethylene glycol (PEG) as a bulk impregnation agent is commonly applied. PEG maintains the wood in a swollen state during drying. However, swelling of wood can reduce its mechanical properties. In this study, the cellular structure of oak and cell wall swelling was characterized by scanning electron microscopy (SEM) of transverse cross-sections, and the microfibril angle of oak fibers was determined by wide angle X-ray scattering (WAXS). Samples of recent European oak (Quercus robur L) impregnated with PEG (molecular weight of 600) were tested in axial tension and radial compression. Mechanical tests showed that axial tensile modulus and strength were only slightly affected by PEG, whereas radial compressive modulus and yield strength were reduced by up to 50%. This behavior can be explained by the microstructure and deformation mechanisms of the material. Microfibril angles in tensile test samples were close to zero. This implies tensile loading of cellulose microfibrils within the fiber cell walls without almost any shear in the adjacent amorphous matrix. These results are important because they can help separate the impact of PEG on mechanical properties from that of chemical degradation in archaeological artifacts, which display only small to moderate biological degradation.

The Influence of Boron on Structure and Mechanical Properties of Bainite Ductile Iron in the Step Austempering in Room Temperature Machine Oil

2010 ◽  
Vol 139-141 ◽  
pp. 235-238
Author(s):  
De Qiang Wei
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Cast Iron ◽  
Impact Strength ◽  
Ductile Iron ◽  
Room Temperature ◽  
Solute Drag ◽  
Ductile Cast Iron ◽  
Treatment Technique ◽  
The Impact

In this paper, the low alloy bainite ductile cast iron has been obtained by a new heat treatment technique of the step austempering in room-temperature machine oil. The effects of element boron, manganese and copper on structure and mechanical properties of the bainite ductile cast Iron in above-mentioned process are investigated. The phenomenon, hardness lag of the alloyed bainite ductile cast Iron, has been discussed. It shows that after the step austempering in room-temperature machine oil, the hardness will increases with the time. It is found that boron and manganese can increase the hardness and reduce the impact strength while copper can increase the impact strength. The results show that reasonable alloyed elements can improve mechanical properties of the bainite ductile cast Iron. Essentially, hardness lag of the alloyed bainite ductile cast Iron is resulted from solute drag-like effect.

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