The Experimental Study on Sensitivity of Hydrogen Embrittlement of 20Cr2Ni4A High-Strength Steel Cleaned by Ultrasonic and Deruster

2011 ◽  
Vol 291-294 ◽  
pp. 1136-1140
Author(s):  
Ling Dong Meng ◽  
Qing Zhang ◽  
Zhi Jie Liang
Keyword(s):  
Experimental Study ◽  
Hydrogen Embrittlement ◽  
High Strength ◽  
Sem Analysis ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Mechanics Performance ◽  
Long Time ◽  
Short Time ◽  
Rupture Mechanism

In order to test whether there is the change of mechanics performance cleaned by ultrasonic and deruster, the experiments on mechanics performance and sensitivity of hydrogen embrittlement have been conducted. During the experiments, 20Cr2Ni4A steel are selected as the materials, which endure the relatively great concussion load in the bad condition, and the gaps’ long-time permanence experiments and short-time tension and concussion experiments have been done. Through the compare of mechanics performances and the SEM analysis of tensile fracture surface of the samples, it can be proved that the mechanics performances and rupture mechanism are the same, no matter whether the materials are cleaned by ultrasonic and deruster or not. These indicate that it doesn’t bring the change of mechanics performances and hydrogen embrittlement to clean the materialss by ultrasonic and deruster.

Research on Friction and Wear Properties of MC Nylon/ Carbon Nanotubes Composites

2013 ◽  
Vol 662 ◽  
pp. 40-43
Author(s):  
Tie Jun Ge ◽  
Jing Wang ◽  
Wei He
Keyword(s):  
Friction And Wear ◽  
Adhesive Wear ◽  
In Situ Polymerization ◽  
Weight Percent ◽  
Wear Properties ◽  
Mechanics Performance ◽  
Long Time ◽  
Carbon Nano Tubes ◽  
Friction And Wear Properties ◽  
Short Time

In this article, MC nylon/carbon nano tubes (CNTs) composites were prepared by in-situ polymerization method. The friction and wear properties were determined. The sample wear surface morphology carried out by scanning electron microscope (SEM) and the wear mechanism was investigated. It was found that the friction coefficient of composites has decreased with the amount of CNTs increasing in the composites. Addition amount of CNTs is up to 0.3% (weight percent), abrasion index decreased to minimum. The abrasion index of the sample of wearing a long time is smaller than that of the sample of wearing a short time. The sample with wearing less time mainly take place adhesive wear, however, mainly happen abrasive wear and adhesive wear for wearing time is longer. Further more, carbon nano tubes (CNTs) are not only improve the wear resistance of composites but also improve the mechanics performance.

A Comparison of Some Carbon Molybdenum Steels on the Basis of Various Creep Limits

1948 ◽  
Vol 159 (1) ◽  
pp. 165-172 ◽  
Author(s):  
A. E. Johnson ◽  
H. J. Tapsell
Keyword(s):  
Experimental Study ◽  
Experimental Work ◽  
Carbon Steels ◽  
Prolonged Heating ◽  
Time Service ◽  
Long Time ◽  
Engineering Materials ◽  
Short Time ◽  
The Relationship ◽  
Creep Limits

A previous report gave the results of an experimental study of the relationship between short-time and long-time creep limits of a number of carbon steels. Certain conclusions were drawn which it was realized were not necessarily applicable to other types of steel. Similar experimental work has since been carried out on six carbon molybdenum steels, and the results obtained indicate similar limitations in the applicability of short-time creep limits to estimation of design stresses for long-time service, as were disclosed by the prior tests on carbon steels. There is not, at first sight, any reason why short-time and long-time creep limits should correlate, since with most engineering materials metallurgical changes occur during prolonged heating.

scholarly journals Study on Micro - Nano Sized Al2O3 Particles on Mechanical, Wear and Fracture Behavior of Al7075 Metal Matrix Composites

2021 ◽  
Vol 15 (58) ◽  
pp. 166-178
Author(s):  
M. Ravikumar ◽  
H. N. Reddappa ◽  
R. Suresh ◽  
E. R. Babu ◽  
C. R. Nagaraja
Keyword(s):  
Tensile Strength ◽  
Wear Resistance ◽  
Research Work ◽  
Sem Analysis ◽  
Tensile Fracture ◽  
High Wear Resistance ◽  
Matrix Composites ◽  
Wear Properties ◽  
Tensile Fracture Surface ◽  
Alumina Oxide

Having Low density and being Light weight with better mechanical properties, aluminum is the most significant material and is universally used in highly critical applications like navy, aerospace and particularly automotive activities. This research work is aimed to investigate the effect of micro and nano boron Al2O3 (Alumina Oxide) to aluminium (Al) on the mechanical and wear properties of the Al composites. The micro - nano composites with 1, 2, 3 and 4 % of Al2O3 particulates in Al are fabricated using stircasting processes. It was found that an increase of Al2O3 both as micro and nano particulates content resulted in an improved hardness, enhanced tensile strength and high wear resistance. However, nano Al2O3 reinforced MMCs have better hardness, improved tensile strength and higher wear resistance as compared with micro sized Al2O3 reinforced MMCs. Grain refinement of composite and nano composite materials as compared with pure Al were observed from the microscopic images. Analysis of wornout surface and tensile fracture surface were studied by SEM analysis to examine the nature of wear and tensile fracture mode of composite samples.

Effects of Different Microalloying and Controlled Cooling Technology on Microstructure and Properties of 500MPa High-Strength Rebars

2014 ◽  
Vol 633-634 ◽  
pp. 168-175
Author(s):  
Wei Chen ◽  
Jian Chun Cao ◽  
Zhe Shi ◽  
Yin Hui Yang ◽  
Yu Zhao
Keyword(s):  
Testing Machine ◽  
High Strength ◽  
Good Effect ◽  
Tensile Fracture ◽  
Controlled Cooling ◽  
Tensile Testing Machine ◽  
Impact Machine ◽  
Obvious Effect ◽  
Tensile Fracture Surface ◽  
Cooling Technology

The mechanical properties and microstructures of three different VN, Nb, V-Nb microalloyed rebars were investigated by using tensile testing machine, impact machine, metallographic microscopy, scaning electron microcopy, transmission electron microscopy and X-ray diffraction apparatus. The results showed that the microstructure of V-Nb microalloyed specimen is consisted of ferrite, pearlite and a small amount of fine bainite (6.7wt%), and obvious effect of grain refinement was obtained with more than 10 size grade of ferrite grain, showing optimal comprehensive properties. SEM micrograph of tensile fracture surface for V-Nb microalloyed 500MPa high-strength rebar is dimple and ductile, ductile-brittle transformation temperature is lower than-30°C, which has good plasticity-toughness and impact toughness at low temperature. The results of precipitates have shown that a large number of small and dispersive V(CN) and Nb (CN) precipitates with size of 5~30nm are formed, good effect of precipitation strengthening was achieved in 500MPa high-strength rebars produced by different microalloying and controlled cooling technology.

Mechanical Properties, Oxidation Resistance and Their Interaction for Two Gas Turbine Seal Ring Alloys

1992 ◽  
Author(s):  
S. K. Srivastava
Keyword(s):  
Gas Turbine ◽  
Oxidation Resistance ◽  
Stress Rupture ◽  
High Strength ◽  
Low Thermal Expansion ◽  
Static Oxidation ◽  
Long Time ◽  
Short Time ◽  
Stress Rupture Testing ◽  
Invar Type

HAYNES® 242™ alloy is a recently developed Ni-25Mo-8Cr alloy primarily for gas-turbine components requiring a combination of low-thermal expansion and high strength, such as seal rings. INCOLOY® alloy 909 is an iron-base Invar-type alloy used in similar applications. Alloy 909 exhibits substantial advantages over 242 alloy in RT and 650°C (1200°F) - 0.2% yield strength, although at considerable loss of ductility and toughness. In stress-rupture testing over a range of 540°-760°C (1000–1400°F), the 100-hr rupture strengths of alloy 909 are consistently inferior to those of the 242 alloy. This dichotomy in short-time versus long-time tensile properties is likely due to the poor oxidation resistance of alloy 909. Comparative static oxidation and oxidation data concurrent with stress-rupture testing for the two alloys are presented and discussed.

scholarly journals Effects of Hot Stamping and Tempering on Hydrogen Embrittlement of a Low-Carbon Boron-Alloyed Steel

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2507 ◽  
Author(s):  
Yongjian Zhang ◽  
Weijun Hui ◽  
Xiaoli Zhao ◽  
Cunyu Wang ◽  
Han Dong
Keyword(s):  
Low Temperature ◽  
Hydrogen Embrittlement ◽  
Hot Stamping ◽  
High Strength ◽  
Hydrogen Desorption ◽  
Sem Analysis ◽  
Alloyed Steel ◽  
Transgranular Fracture ◽  
Low Carbon ◽  
Tempering Treatment

The effects of hot stamping (HS) and tempering on the hydrogen embrittlement (HE) behavior of a low-carbon boron-alloyed steel were studied by using slow strain rate tensile (SSRT) tests on notched sheet specimens. It was found that an additional significant hydrogen desorption peak at round 65–80 °C appeared after hydrogen-charging, the corresponding hydrogen concentration (CHr) of the HS specimen was higher than that of the directed quenched (DQ) specimen, and subsequent low-temperature tempering gave rise to a decrease of CHr. The DQ specimen exhibited a comparatively high HE susceptibility, while tempering treatment at 100 °C could notably alleviate it by a relative decrease of ~24% at no expanse of strength and ductility. The HS specimen demonstrated much lower HE susceptibility compared with the DQ specimen, and tempering at 200 °C could further alleviate its HE susceptibility. SEM analysis of fractured SSRT surfaces revealed that the DQ specimen showed a mixed transgranular-intergranular fracture, while the HS and low-temperature tempered specimens exhibited a predominant quasi-cleavage transgranular fracture. Based on the obtained results, we propose that a modified HS process coupled with low-temperature tempering treatment is a promising and feasible approach to ensure a low HE susceptibility for high-strength automobile parts made of this type of steel.

scholarly journals Improved mechanical and viscoelastic properties of CNT-composites fabricated using an innovative ultrasonic dual mixing technique

2020 ◽  
Vol 29 (1) ◽  
pp. 77-85
Author(s):  
Shailesh I. Kundalwal ◽  
Ankit Rathi
Keyword(s):  
Epoxy Matrix ◽  
Viscoelastic Properties ◽  
High Strength ◽  
Critical Issue ◽  
Tensile Fracture ◽  
Epoxy Nanocomposites ◽  
Multiwalled Carbon ◽  
Tensile Fracture Surface ◽  
Lap Shear ◽  
Uniform Dispersion

AbstractCarbon nanotube (CNT) acts as the most promising nanofiller due to its high aspect ratio and exceptional nanoscale-level properties. However, the dispersibility of CNTs in the conventional polymer matrices is a very critical issue in developing the high-strength and light-weight polymer-based nanocomposites. In this study, an attempt was made to develop cluster-free and uniform dispersion of multiwalled carbon nanotubes (MWCNTs) in the epoxy matrix using an innovative ultrasonic dual mixing technique. The effect of dispersion of MWCNTs on the mechanical and viscoelastic properties of MWCNT-epoxy nanocomposites was comprehensively studied. Our results reveal that the tensile strength and toughness of epoxy nanocomposites with 0.50 wt.% of MWCNTs improved by 21% and 46%, respectively, as compared to neat epoxy. The nanocomposite samples with the same CNT loading show maximum enhancements of 22% and 26% in the lap shear strength and storage modulus, respectively. The tensile fracture surface examination of MWCNT-epoxy nanocomposites using field emission scanning electron microscopy indicated the cluster-free and uniform dispersion of MWC-NTs in the epoxy matrix.

Effect of Heat Treatment on the Organization and Properties in Liquid Forging

2012 ◽  
Vol 430-432 ◽  
pp. 202-204
Author(s):  
Chun Li ◽  
Jia Xuan Wang ◽  
Hua Qing Miao
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Artificial Aging ◽  
Natural Aging ◽  
Tensile Fracture ◽  
Tensile Fracture Surface ◽  
Forging Process ◽  
Mechanics Performance ◽  
Fracture Surface Analysis ◽  
And Performance

In this paper, based on the liquid forging part flange LY12, the influence of heat treatment on the organization and performance of the liquid forging part was studied through microstructure, mechanical properties and tensile fracture surface analysis methods, this article also has some guiding significance to the formulation of the best liquid forging process parameters. The results show that the sample after natural aging which mechanics performance is best, and grain is relatively small; the latter two that after artificial aging are relatively poor. With the extension of artificial aging time, the mechanical properties and the organization has a descending trend.

Short-Time Tests for Long-Time Endurance

1923 ◽  
Vol 128 (4) ◽  
pp. 264-264
Author(s):  
J. W. Harsch
Keyword(s):  
Long Time ◽  
Short Time
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