Microstructure and mechanical behavior of cast Ti-6Al-4V with addition of boron

2012 ◽  
Vol 2 (3) ◽  
Author(s):  
Robert Pederson ◽  
Raghuveer Gaddam ◽  
Marta-Lena Antti
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Compressive Yield Strength ◽  
Strain Rates ◽  
Beta Transus ◽  
Microstructural Refinement ◽  
Compression Properties ◽  
Transus Temperature ◽  
Cast Microstructure

AbstractThe effect of boron (between 0.06 and 0.11 wt%) on the microstructure, hardness and compression properties of cast Ti-6Al-4V was investigated. Compression properties were examined in the temperature range from room temperature to 1000°C. It was found that the addition of boron refines the as-cast microstructure in terms of prior beta grain size and alpha colony size. This microstructural refinement led to an increase in compressive yield strength from room temperature up to 700°C. Three different strain rates (0.001, 0.1 and 1 s−1) were evaluated during compression testing from which it was found that the compressive yield strength decreased with decreasing strain rate from 600°C up to the beta transus temperature.

Effect of Hydrogen Content on Structure and Properties of Sintering Body Utilizing TC21 Hydrogenated Powder

2012 ◽  
Vol 581-582 ◽  
pp. 777-781
Author(s):  
Ya Qiang Tian ◽  
Ying Li Wei ◽  
Hong Liang Hou ◽  
Xue Ping Ren
Keyword(s):  
Mechanical Property ◽  
Grain Size ◽  
Titanium Alloy ◽  
Yield Strength ◽  
Hydrogen Content ◽  
Room Temperature ◽  
Sintered Body ◽  
Compressive Yield Strength ◽  
Structure And Properties ◽  
Die Forming

The effect of hydrogenation on structure and properties of TC21 alloy by die forming and sintering using hydrogenated powder was researched by means of the room-temperature die forming and sintering in protection air to produce titanium alloy. The results show that the structure of TC21 titanium sintered body using hydrogenated powder with hydrogen content of 0.39 wt% by die forming and sintering is thinner and the density is higher than the others. The compression strength and compressive yield strength of TC21 sintered body with hydrogen content of 0.39 wt% are well. With hydrogen content increasing, the structure of TC21 production using hydrogenated powder by die forming and sintering gets well and the grain size becomes smaller. After annealing, the structure of TC21 titanium production gets more uniformity and refinement obviously, and the hydrogen content of TC21 alloy safety state is achieved. In the end, the density and mechanical property of TC21 titanium alloy sintered body with hydrogen content of 0.39wt % is the best.

Nanocrystalline FCC Thin Films Are More Prone to RT Creep Than What We Think

2009 ◽  
Author(s):  
Nikhil Karanjgaokar ◽  
Ioannis Chasiotis
Keyword(s):  
Thin Films ◽  
Grain Size ◽  
Steady State ◽  
Yield Strength ◽  
Time Scales ◽  
Room Temperature ◽  
Primary Creep ◽  
Steady State Creep ◽  
Strain Rates ◽  
Creep Response

Although nanocrystalline (Nc) metallic thin films are excellent candidate materials for Microelectromechanical Systems (MEMS) and microelectronics due to their outstanding yield strength, serious reliability concerns arise from their increased room temperature creep rates. A comprehensive experimental investigation was carried out to extract the strain-rate dependent mechanical behavior of Au (38 nm grain size) and Ni (20 nm grain size) micron-thin films conducted for the very first time at strain rates in the broad range of 10−6 – 10 /s which spans time scales from ms to hours. Nc-Au films demonstrated a clear bi-linear change in their inelastic properties, i.e. the elastic limit and its yield strength, while the Nc-Ni films showed a linear increase in their inelastic properties over the same loading rates. This unexpected trend for the Au films emphasized the significant contribution of room temperature (RT) creep at strain rates between 10−6 – 10−4 /s, at which rate, larger grain size materials are not prone to creep at RT. This realization prompted a series of novel microscale creep experiments, the first of their kind, at time scales of 104–105 s. An important finding was that the first stage of creep, primary creep, proceeds at a very fast rate, of the order of 10−7 /s, lasting for 5–6 hours after the application of a stress. Furthermore, multi-stage creep experiments revealed that the primary creep rate decreased with the order of creep cycle, while the steady state creep response remained the same in all creep cycles. This creep response of nanocrystalline FCC films was modeled via a non-linear viscoelastic creep model that captured the effect of applied stress on both primary and steady-state creep regimes.

Influence of Isothermal Forging Temperature on Microstructure and Tensile Properties of Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb-0.4Si-1.5Ta Near-α Titanium Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 153-157
Author(s):  
Tao Wang ◽  
Hong Zhen Guo ◽  
Jian Hua Zhang ◽  
Ze Kun Yao
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Titanium Alloy ◽  
Tensile Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Constant Strain Rate ◽  
Isothermal Forging ◽  
Α Phase ◽  
Transus Temperature

The microstructures and room temperature and 600°C tensile properties of Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb -0.4Si-1.5Ta alloy after isothermal forging have been studied. The forging temperature range was from 850°C to 1075°C, and the constant strain rate of 8×10-3/S-1 was adopted. With the increase of forging temperature, the volume fraction of primary α phase decreased and the lamellar α phase became thicker when the temperatures were in range of 850°C -1040°C; The grain size became uneven and the α phase had different forms when the forging temperature was 1040°C and 1075°C respectively; The tensile strength was not sensitive to the temperature and the most difference was within 20MPa. Tensile strength and yield strength attained to the maximum when temperature was 1020°C; the ductility decreased with the increase of forging temperature, and this trend became more obvious if forging temperature was above the β-transus temperature.

The Strength and Ductility of Intermetallic Compounds: Grain Size Effects

1986 ◽  
Vol 81 ◽  
Author(s):  
E.M. Schulson ◽  
I. Baker ◽  
H.J. Frost
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Intermetallic Compounds ◽  
Size Effects ◽  
Nickel Aluminide ◽  
Marked Reduction ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
The Relationship ◽  
Strength And Ductility

Since writing on this subject two years ago [1], a number of developments have occurred, particularly in relation to the mechanical properties of the L12 nickel aluminide Ni3Al. Some elucidate the nature of the yield strength and the extraordinarily beneficial effect of boron on low-temperature ductility. Some others expose, at least in part, the nature of the marked reduction in ductility at elevated temperatures. Another considers the mechanisms dominating creep deformation. Also during this period, contradictions have appeared: the relationship between the yield strength and the grain size, d, at room temperature has been contested, and opposing views of grain refinement on ductility have been reported.This paper reviews these developments. Although broadly directed at intermetallic compounds, the discussion is specific to Ni3Al. The hope is that the knowledge and understanding gained about this compound will benefit the class as a whole.

Grain Size Dependence of Tensile Properties in Cu-Sn Thin Foils (Experimental Study)

2015 ◽  
Vol 736 ◽  
pp. 19-23
Author(s):  
Taek Kyun Jung ◽  
Hyo Soo Lee ◽  
Hyouk Chon Kwon
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Experimental Study ◽  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Size Dependence ◽  
Yield Drop ◽  
Thin Foils ◽  
Vacuum Atmosphere

This study was carried out to investigate the effects of grain size on mechanical properties in Cu-Sn foil with a thickness of 30 um. The grain size was varied from approximately 7 um to 50 um using heat treatment at 773 K for 2 h to 24 h in a vacuum atmosphere. Tensile test was carried out at room temperature with strain rate of 1mm/min. Typical yield drop phenomenon was observed. Mechanical properties were found to be strongly affected by microstructural features including grain size. The yield strength and tensile strength gradually decreased with increasing the grain size. The strain to fracture also decreased by grain growth. These results could be explained by not only the grain size dependence of yield strength but also the ratio of thickness to grain size dependence of yield strength.

scholarly journals Tensile Strength and Creep Resistance in Nanocrystalline Cu, Pd and Ag

1990 ◽  
Vol 206 ◽  
Author(s):  
G. W. Nieman ◽  
J. R. Weertman ◽  
R. W. Siegel
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Yield Strength ◽  
Creep Resistance ◽  
Room Temperature ◽  
True Strain ◽  
Constant Load ◽  
Creep Tests ◽  
Grain Sizes

ABSTRACTMeasurements of tensile strength and creep resistance have been made on bulk samples of nanocrystalline Cu, Pd and Ag consolidated from powders by cold compaction. Samples of Cu-Cu2O have also been tested. Yield strength for samples with mean grain sizes of 5–80 nm and bulk densities on the order of 95% of theoretical density are increased 2–5 times over that measured in pure, annealed samples of the same composition with micrometer grain sizes. Ductility in the nanocrystalline Cu has exceeded 6% true strain, however, nanocrystalline Pd samples were much less ductile. Constant load creep tests performed at room temperature at stresses of >100 MPa indicate logarithmic creep. The mechanical properties results are interpreted to be due to grain size-related strengthening and processing flaw-related weakening.

Effect of RE Addition on Microstructure and Properties of As-Cast Mg-6Zn-Zr Alloy

2013 ◽  
Vol 711 ◽  
pp. 110-114
Author(s):  
Seung Jin Lee ◽  
Joon Sik Park ◽  
Jeong Min Kim ◽  
Ki Tae Kim
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Tensile Strength ◽  
Corrosion Resistance ◽  
Room Temperature ◽  
Filling Ability ◽  
High Microhardness ◽  
Cast Microstructure ◽  
Zr Alloy ◽  
Zr Alloys

Typical as-cast microstructure of the MgZnRE-Zr alloys consists primarily of Mg matrix, MgZn and MgRE phases. Although the electrical conductivity was a slightly reduced by Ce-rich RE addition, the conductivity was remained high. Microhardness at room temperature and tensile strength at 200°C were clearly enhanced by the addition. Fluidity as mold filling ability was observed to increase significantly with the RE addition partly due to reduced grain size and solidification range, however the corrosion resistance predicted from polarization curves was little decreased.

scholarly journals Achieving High Yield Strength and Ductility in As-Extruded Mg-0.5Sr Alloy by High Mn–Alloying

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4176
Author(s):  
Shibo Zhou ◽  
Xiongjiangchuan He ◽  
Peng Peng ◽  
Tingting Liu ◽  
Guangmin Sheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Tensile Yield Strength ◽  
High Yield ◽  
Compressive Yield Strength ◽  
High Yield Strength ◽  
Pinning Effect ◽  
Small Grains ◽  
Strength And Ductility

The effect of Mn on the microstructure and mechanical properties of as-extruded Mg-0.5Sr alloy were discussed in this work. The results showed that high Mn alloying (2 wt.%) could significantly improve the mechanical properties of the alloys, namely, the tensile and compressive yield strength. The grain size of as-extruded Mg-0.5Sr alloys significantly was refined from 2.78 μm to 1.15 μm due to the pinning effect by fine α-Mn precipitates during the extrusion. Moreover, it also showed that the tensile yield strength and the compressive yield strength of Mg-0.5Sr-2Mn alloy were 32 and 40 percent age higher than those of Mg-0.5Sr alloy, respectively. Moreover, the strain hardening behaviors of the Mg-0.5Sr-2Mn alloy were discussed, which proved that a large number of small grains and texture have an important role in improving mechanical properties.

Observation of slip propagation across grain boundaries in Ni3Al

1986 ◽  
Vol 44 ◽  
pp. 864-865 ◽  
Author(s):  
I. Baker ◽  
E.M. Schulson ◽  
J.A. Horton
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Room Temperature ◽  
Size Dependence ◽  
Direct Evidence ◽  
Specimen Preparation ◽  
Fine Grained ◽  
Room Temperature Yield Strength ◽  
Pile Up ◽  
Preparation Techniques

Recent modelling of the grain size dependence of the room-temperature yield strength of Ni3Al has invoked the concept of dislocation pile-ups. The idea is that the yield strength measured in the Liiders regime (i.e. the Liiders band propagation stress) represents not the stress to independently nucleate slip in each grain but the stress required to propagate slip through the material. This paper presents direct evidence of slip propagation from one grain to the next and thus validation of the use of a pile-up model for Ni3Al.Miniature tensile specimens (3 mm x 7 mm x0.2 mm), made from an extruded rod of fine-grained (∽10 μm) Ni3Al containing 0.35 at.% boron, were strained under tension whilst being observed in a Philips EM 430T operated at 300 KV. Details of the design and operation of the straining stage and of the specimen preparation techniques are given elsewhere.

Effect of hafnium addition on a Ni-Al-Co Alloy

1990 ◽  
Vol 48 (4) ◽  
pp. 940-941
Author(s):  
L. S. Lin ◽  
G. W. Levan ◽  
S. M. Russell ◽  
C. C. Law
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Grain Boundaries ◽  
Ternary Alloy ◽  
Room Temperature ◽  
Gamma Prime ◽  
Room Temperature Ductility ◽  
Appreciable Increase ◽  
Hf Addition

Recent efforts at P&W have shown that the addition of cobalt to binary NiAl results in an appreciable increase in room temperature ductility. One version of this ternary alloy, designated VIM A, has a composition of Ni-30 at.% Al-35 at.% Co. The addition of 0.5 at.% Hf to this alloy (designated VIM AH) results in an improvement in yield strength at 760°C. Room temperature properties were not found to be significantly affected by the Hf addition. This discussion will focus on the microstructures of alloys VIM A and VIM AH and their relationship to the mechanical properties observed in compression at room temperature and 760°C.The addition of hafnium reduced the grain size of VIM AH alloy. After room temperature compression, both alloys show an ordered bcc (B2) matrix and precipitates which are distributed primarily along grain boundaries. These precipitates were identified by microdiffraction to be ordered fcc (L12) gamma prime for VIM A and hexagonal (A3) for VIM AH.

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