Effect of N Content on Mechanical Properties and Microstructure of Alloy 690

2009 ◽  
Author(s):  
Kui Liu ◽  
Xianchao Hao ◽  
Ming Gao ◽  
Shuo Li ◽  
Yiyi Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Room Temperature ◽  
N Content ◽  
Solution Treated ◽  
Alloy 690 ◽  
Significant Difference ◽  
Tension Testing ◽  
Austenite Grains ◽  
Reduction In Area

The microstructures and mechanical properties of nitrogen bearing Alloy 690 have been systematically investigated. Alloy ingots with different N addition, range from 38 to 330wt.ppm, were melted using vacuum induction melting (VIM) plus electro-slag re-melting (ESR) double processing techniques. The forged and hot rolled different N content bars were solid solution treated between 1010°C and 1080°C, thermally treated at 715°C for different state mechanical property testing and microstructure study. Microstructure analysis indicated that nitrogen addition to Alloy 690 can effectively refine the solution treated austenite grains. This may be associated with titanium nitrides pinning the grain boundaries and hindering the grain growth during solid solution treatment. More nitrides, which are identified as TiN, were found on the grain boundaries and in the inside of austenite grains with increasing N contents of the alloy. The carbide precipitation at 715°C showed significant difference identified by SEM. At the level of 38, 100 and 220wt.ppm N, the chromium carbide Cr23C6 distribution on the grain boundaries appeared to be semi-continuous; when the N content reached 330wt.ppm, only few discrete type of carbides were observed. The tension testing results at room temperature of different N content alloys proved that both the ultimate tensile strength (UTS) and the yield strength (YS) enhanced about 50MPa when N content was raised from 38 to 330wt.ppm in this alloy; while the corresponding elongation (EL) and reduction in area (RA) adversely dropped about 5%. Room temperature hardness rose with increasing N content, well matched tensile strength. High temperature tension testing results at the range of 900∼1250°C showed that a severely hot ductility dip, representing by the values of the reduction in area (RA), existed in 300wt.ppm and 100wt.ppm nitrogen containing alloys at the lower end temperature range of 950∼1100°C. However, such ductility dip could be improved when the N content was at 220wt.ppm, and completely eliminated at 38wt.ppm N content. At the higher end temperature rang of 1150∼1250°C, the ductility of all 4 nitrogen bearing alloys did not show significant difference, even though the hot ductility of minimum 38wt.ppm N samples was preferable. Nitrogen content did not affect high temperature strength; the UTS values nearly had no change at the same testing temperature with different nitrogen bearing alloys. The carbide precipitation difference of the thermally treated alloy, induced by N addition, may affect Alloy 690 corrosion properties, which needs to be studied in future. The mechanical properties variation both at room temperature and high temperatures of different nitrogen bearing alloys in this study will be certainly beneficial to determine the practical processing routes of Alloy 690.

Research on Semi-Solid Deformation and Forging Behavior of Ti14 Alloy

2007 ◽  
Vol 546-549 ◽  
pp. 1373-1378 ◽  
Author(s):  
Yong Qing Zhao ◽  
J.F. Wei ◽  
Wei Lu Wu ◽  
P. Guo
Keyword(s):  
Mechanical Properties ◽  
Grain Boundaries ◽  
Room Temperature ◽  
Low Cost ◽  
Coarse Grain ◽  
Solid Deformation ◽  
Comprehensive Properties ◽  
Fine Microstructure ◽  
Semi Solid ◽  
Solid Forging

Titanium and its alloys are widely used in industries due to their excellent comprehensive properties. However, their high-cost limits their applications in civil, therefore the research on low cost titanium technology is necessary. In the present study, the semi-solid deformation behavior of Ti14 burn resistant alloy was investigated. The results indicated that Ti2Cu melting phases within grains and at grain boundaries grow to form coarse grain boundaries and network structures during Ti14 alloy semi-solid deformation. Its microstructure was coarse and the grain boundary was wide after semi-solid forging, leading to low plasticity at room temperature. Recrystallizing heat treatment leads to fine microstructure, which is similar to that of conventional forging, resulting in improvement of tensile mechanical properties. The mechanical properties of semi-solid forging are similar to that of conventional one at high temperature.

Effect of the Sintering Additives on the Microstructure and the Properties of Textured Silicon Nitride

2005 ◽  
Vol 287 ◽  
pp. 242-246
Author(s):  
Dong Soo Park ◽  
Y.M. Kim ◽  
Byung Dong Hahn ◽  
Chan Park
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Silicon Nitride ◽  
Flexural Strength ◽  
Room Temperature ◽  
Sintering Additives ◽  
Significant Difference ◽  
Grain Width

Silicon nitride samples without and with 3 wt% of the aligned b-silicon nitride whisker seeds were prepared with 8.2 wt% Er2O3 and 1.9 wt% AlN. After sintering at 2148 K for 4h, the samples exhibited densities higher than 99.5% TD. The microstructures and properties of the samples were compared with those of the samples sintered with 4.8 wt% Y2O3 and 2.2 wt% Al2O3 at 2273 K for 4h. For samples without the whiskers, the sample with 4.8 wt% Y2O3 + 2.2 wt% Al2O3 had coarser microstructures than those with with 8.2 wt% Er2O3 + 1.9 wt% AlN. However, the samples with the whisker seeds, the former sample appeared to have only slightly larger grains than the latter sample in spite of the significant difference in the sintering temperatures. For the samples without the whisker seeds, the room temperature flexural strength was higher for the sample with Er2O3 + AlN. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited higher room temperature flexural strength than that with Er2O3 + AlN although the average grain width of the former sample was larger than that of the latter sample. In case of the high temperature flexural strength at 1673 K, the flexural strengths of the samples with the whisker seeds were higher than double the strengths of the samples without the whisker seeds. For samples without the whisker seeds, the sample with Er2O3 + AlN exhibited better mechanical properties than that with Y2O3 + Al2O3. However, for the samples with the aligned whisker seeds, the sample with Y2O3 + Al2O3 exhibited better mechanical properties than those with Er2O3 + AlN. The results were explained in terms of the microstructures of the samples.

Microstructure and Properties Characterization of Polycrystalline Ni-Fe-Cr-Based Superalloy EP-718E after Electric Upsetting

2016 ◽  
Vol 721 ◽  
pp. 467-472 ◽  
Author(s):  
Lembit Kommel
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Energy Dispersive Spectrometry ◽  
Fatigue Testing ◽  
Tension Stress ◽  
Tension Testing ◽  
Electric Upsetting ◽  
Number Of Cycles ◽  
Cycles To Failure

The purpose of this study is to analyze the effect of electric upsetting on the microstructure defects eliminating and mechanical properties evolution of the Ni-Fe-Cr-based polycrystalline superalloy EP718E. The microstructure was examined by scanning electron microscope and energy dispersive spectrometry techniques. The material mechanical properties were characterized by nanoindentation, by tension testing of micro samples and high cycle fatigue testing at room temperature. The results show, that the microstructure defects on confluence of grain boundaries (depending on the processing stages) were step-by-step eliminated. The tension stress was lowered but elongation was increase. As a result of such changes in microstructure and mechanical properties of alloy the fatigue strength (δ-1) was increased from δ-1 = 300 MPa to δ-1 = 540 MPa and the number of cycles to failure was increased from N1 = 2·107 up to N4 = 4 x (2·107), respectively.

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.

Precipitation of copper in proeutectoid cementite in steel

1990 ◽  
Vol 48 (4) ◽  
pp. 916-917
Author(s):  
F. A. Khalid ◽  
M. Farooque ◽  
D. V. Edmonds
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Previous Analysis ◽  
Ferritic Steels ◽  
Decomposition Reactions ◽  
Boundary Allotriomorphs ◽  
Solution Treated ◽  
Thin Foils ◽  
Austenite Grains ◽  
Parent Austenite

The morphology and mechanism of Cu precipitation in grain boundary allotriomorphs of proeutectoid cementite forming isothermally inaustenite in two Fe-10Mn-3Cu-0.8C and Fe-lOMn- lCu-0.8C (nominal wt%) alloys are being studied. These particular alloys can be partially decomposed to the proeutectoid and eutectoid phases recognisable in ferritic steels, but possess the advantage that unlike ferritic steels the parent austenite phase is retained after cooling to room temperature thus facilitating studies of the decomposition reactions.A 50 g ingot of each experimental alloy was argon arc melted using high purity materials and homogenised. Samples were rolled, swaged and machined to 3mm diameter rod, solution treated at 1200 °C for 1 hr and quenched in water. Specimens were then solutionised at 1200°C for 10 min and isothermally transformed at 615 °C for 4 hrs. Methods for the preparation of thin foils for TEM are given elsewhere.The heat treatment resulted in the formation of grain boundary allotriomorphs of cementite in austenite (Fig 1). TEM confirmed that the cementite allotriomorphs formed with the Pitsch orientation relationship to one of the austenite grains at the grain boundary (Fig 2c ) consistent with a previous analysis.

Influence of Cu on the Mechanical Properties of an Al-4.4wt%Mg Alloy after ECAP

2006 ◽  
Vol 503-504 ◽  
pp. 107-112 ◽  
Author(s):  
Bert Verlinden ◽  
M. Popović
Keyword(s):  
Mechanical Properties ◽  
Aluminium Alloys ◽  
Room Temperature ◽  
Solution Treatment ◽  
Slowing Down ◽  
Cu Alloy ◽  
Solution Treated Condition ◽  
Solution Treated ◽  
Treated Condition ◽  
Fast Increase

Two Aluminium alloys, type AA5182 and AA5182+1.2wt% Cu, have been studied. The second alloy in solution treated condition is 18% stronger than the first one. During ageing at 150°C or 200°C it shows a characteristic fast increase in yield strength during the first minutes of ageing, followed by a 'plateau'. Both materials have been deformed in an ECAP die (4 and 8 passes) at 200°C and the microstructure, hardness and mechanical properties in compression at room temperature have been investigated. Although in none of the two materials a true sub-micron grain size was obtained at 200°C, a fair combination of strength and strain hardening was observed. The AA5182+Cu alloy, when ECAP’ed after a solution treatment and quenching, shows an increase in strength of about 20% compared to the AA5182 reference alloy. A post-ECAP annealing at 200°C does not lead to a further increase in hardness or strength. An analysis of the substructure and the mechanical properties during ECAP led to the conclusion that the precipitates formed during ECAP at 200°C do not directly contribute to the higher strength of alloy AA5182+Cu, but they contribute indirectly by slowing down the recovery.

The Study on Microstructures and Mechanical Properties of Heat Rolled and Solution-Treated Fe-26Mn-6Al-1C Steel

2012 ◽  
Vol 482-484 ◽  
pp. 1530-1533
Author(s):  
Ming Li Huang ◽  
Hua Ying Li ◽  
Hua Ding
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Room Temperature ◽  
Solution Treatment ◽  
Tensile Tests ◽  
Solution Treated ◽  
Sem And Tem ◽  
Hot Rolled

In the present work, mechanical properties and microstructures of hot-rolled and solution-treated Fe-26Mn-6Al-1C steel (6Al steel) were investigated. Tensile tests were carried out at room temperature. The samples were characterized by using XRD, OM, SEM and TEM. The results suggested that the microstructure of the hot rolled 6Al steel was fully austenitic. After solution treatment and deformation, the microstructure was still single austenite. With the increase of the solution treatment temperatures, the strength decreased and the elongation increased. After solution treated at 1100°C for 1h, the yield strength, ultimate tensile strength and elongation were 378MPa, 756MPa and 57%.

Effects of Cooling Rate on the Microstructure and Room Temperature Tensile Properties of Orthorhombic Ti-22Al-21Nb-1Ta-1W Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 817-820
Author(s):  
Dong Luo ◽  
Yu You Cui ◽  
Rui Yang
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Cooling Rate ◽  
Room Temperature ◽  
Lamellar Microstructure ◽  
High Temperature Mechanical Properties ◽  
Solution Treated ◽  
Room Temperature Yield Strength ◽  
Transus Temperature ◽  
O Phase

In order to improve high temperature mechanical properties of Ti2AlNb based alloys, alloying with a combination of Ta and W was studied in the on-going work. The effects of cooling rate after solution heat treatment on the room temperature mechanical properties have been reported in this paper. All samples were solid solution treated at near β transus temperature, cooled at different cooling rates, and then aged at subtransus temperature. Experimental results showed that, with increasing cooling rate, room temperature yield strength decreased sharply to a minimum value, and then increased. Change of elongation exhibits a trend opposite to yield strength. Microstructure of the alloy varied from near lamellar to lamellar plus Widmanstätten, and then to full Widmanstätten structure with the increase of cooling rate, and the faster the cooling rate, the finer the laths of the O phase. The samples with near lamellar microstructure obtained at the cooling rate of 6oC/min possess the best ductility but relatively low yield strength.

Mechanical Properties of Ti-Nb Biomedical Shape Memory Alloys Containing 13- and 14-Group Elements

2005 ◽  
Vol 475-479 ◽  
pp. 2329-2332 ◽  
Author(s):  
Hideki Hosoda ◽  
Yusuke Fukui ◽  
Tomonari Inamura ◽  
Kenji Wakashima ◽  
Shuichi Miyazaki
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Room Temperature ◽  
Solution Hardening ◽  
Good Shape ◽  
Solution Treated ◽  
Beta Titanium ◽  
Shape Memory Properties ◽  
Elongation To Failure

In order to replace Ti-Ni shape memory alloys, new biomedical shape memory alloys have been developed which are composed of beta titanium and nontoxic elements only. In this paper, experimental results of mechanical and shape memory properties are reported for the Ni-free Ti-18mol%Nb shape memory alloys containing 3mol% of 13-group and 14-group ternary elements in the periodic table. The ternary elements selected are Al, Ga, In, Ge and Sn. It was found that the solution treated alloys exhibit good shape memory effect but almost no pseudoelasticity at room temperature. Ultimate tensile strength and elongation to failure at room temperature are ranged from 250 to 710MPa and from 13 to 21%, respectively, depending on the kind of ternary elements. Effect of solution hardening on strength is discussed.

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