Increasing the Intensity of Cementation Process of Tool Low-Alloy Steels by Surface Laser Treatment

2016 ◽  
Vol 870 ◽  
pp. 377-382 ◽  
Author(s):  
E. Marinin ◽  
S.P. Grachev ◽  
A.L. Flaxman
Keyword(s):  
Surface Layer ◽  
Laser Treatment ◽  
Laser Emission ◽  
Low Alloy Steels ◽  
Test Results ◽  
Emission Power ◽  
Microstructure Formation ◽  
Alloy Tool ◽  
Alloy Steels ◽  
Surface Laser

This work considers the questions of low-alloy tool steel cementation by laser treatment. The model of surface layer carbon saturation from the laser-induced plasma is shown. It is described that the diffusion process in the laser treatment can not be explained only by the influence of temperature gradient. The results of the experimental work confirmed the increasing intensity of the process surface layer saturation with carbon. The work describes the influence of the laser emission power on surface layer microstructure formation. The test results of the hardened samples showed an approximately two-time increase in durability.

Microstructures and Properties of HAZ of JB800 Bainite Steel

2014 ◽  
Vol 670-671 ◽  
pp. 65-69
Author(s):  
Jun Sheng Sun ◽  
Hong Quan Wang
Keyword(s):  
Impact Toughness ◽  
Lower Cost ◽  
Welding Process ◽  
High Strength ◽  
Granular Bainite ◽  
Low Alloy Steels ◽  
Test Results ◽  
Bainite Steel ◽  
Alloy Steels ◽  
Allotriomorphic Ferrite

JB800 steel has grain boundary allotriomorphic ferrite and granular bainite (FGBA/BG), and it is a kind of high strength low alloy steels, which has simple produce procedure, lower cost and excelled property. The law of microstructure transformation in CGHAZ, hardness, and impact toughness in HAZ of JB800 steel were studied by means of thermal simulation. The test results show that under the general condition of welding process (t8/5=5~50s), microstructure of CGHAZ is composed of mixture microstructure of Martensite and Bainite and with the increase of cooling rate, the content of Martensite will decrease, but that of Bainite will increase; when t8/5 is 20s, CGHAZ zone have better impact toughness, which is composed of 95% Martensite and 5% Bainite. Therefore t8/5 should be controlled at about 20s to get better impact toughness.

Review and Consideration of Unsettled Problems on Evaluation of Fatigue Damage in LWR Water

2006 ◽  
Vol 129 (1) ◽  
pp. 186-194
Author(s):  
Makoto Higuchi ◽  
Katsumi Sakaguchi
Keyword(s):  
Fatigue Life ◽  
Mechanical Test ◽  
Low Alloy Steels ◽  
Test Results ◽  
Considerable Effort ◽  
Test Conditions ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Fatigue Life Reduction ◽  
Year 2000

Reduction in the fatigue life of structural materials of nuclear components in Light Water Reactor (LWR) water was initially detected and examined by the authors in the 1980s, who subsequently directed considerable effort to the development of a method for evaluating this reduction quantitatively. Since the first proposal of equations to calculate environmental fatigue life reduction for carbon and low-alloy steels was published in 1985 by Higuchi and Sakamoto (J. Iron Steel Inst. Jpn. 71, pp. 101–107), many revisions were made based on a lot of additional fatigue data in various environmental and mechanical test conditions. The latest models for evaluation using Fen of the environmental fatigue life correction factor were proposed for carbon and low alloy steels in the year 2000 and for austenitic stainless steel, in 2002. Fen depends on some essential variables such as material, strain rate, temperature, dissolved oxygen and sulfur concentration in steel. The equation for determining Fen is given by each parameter for each material. These models, having been developed three to five years ago, should be properly revised based on new test results. This paper reviews and discusses five major topics pertinent to such revision.

scholarly journals Tensile Testing of Carbon Steel in High Pressure Hydrogen

2007 ◽  
Author(s):  
Andrew Duncan ◽  
Poh-Sang Lam ◽  
Thad Adams
Keyword(s):  
High Pressure ◽  
Carbon Steel ◽  
Alternative Energy ◽  
Room Temperature ◽  
Structural Integrity ◽  
Mechanical Test ◽  
Low Alloy Steels ◽  
Test Results ◽  
Alloy Steels ◽  
Pressure Hydrogen

An infrastructure of new and existing pipelines and systems will be required to carry and to deliver hydrogen as an alternative energy source under the hydrogen economy. Carbon and low alloy steels of moderate strength are currently used in hydrogen delivery systems as well as in the existing natural gas systems. It is critical to understand the material response of these standard pipeline materials when they are subjected to pressurized hydrogen environments. The methods and results from a testing program to quantify hydrogen effects on mechanical properties of carbon steel pipeline and pipeline weld materials are provided. Tensile properties of one type of steel (A106 Grade B) in base metal, welded and heat affected zone conditions were tested at room temperature in air and high pressure (10.34 MPa or 1500 psig) hydrogen. A general reduction in the materials ability to plastically deform was noted in this material when specimens were tested in hydrogen. Furthermore, the primary mode of fracture was changed from ductile rupture in air to cleavage with secondary tearing in hydrogen. The mechanical test results will be applied in future analyses to evaluate service life of the pipelines. The results are also envisioned to be part of the bases for construction codes and structural integrity demonstrations for hydrogen service pipeline and vessels.

Microstructures and Microhardness of SNCed Medium Carbon Low Alloy Steels

2005 ◽  
Vol 475-479 ◽  
pp. 137-140 ◽  
Author(s):  
Jun Bao Zhang ◽  
Yue Lian Liu ◽  
Xin Qing Zhao ◽  
J. Wu ◽  
Hong Wei Song ◽  
...  
Keyword(s):  
Indentation Test ◽  
Low Alloy Steels ◽  
Test Results ◽  
Medium Carbon ◽  
Nano Indentation ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Alloy Steels ◽  
Nanostructured Layers ◽  
Means Of Transmission

Nanostructured layers were fabricated on the surface of 0.4C-1.0Cr and 1.0C-1.5Cr low alloy steels by using an ultrasonic particulate peening (USPP) technique. The microstructures and mechanical properties of the nanocrystallized layers were characterized by means of transmission electron microscopy, and nano-indentation test. Results showed that the average grain size in the surface nanocrystallized layer of 0.4C-1.0Cr and 1.0C-1.5Cr low alloy steel was about 5nm and 10nm, respectively. The nano-indentation hardnesses of the surface nanocrystallized layer were enhanced significantly and reach upwards of 8.0 GPa and 12.5 GPa, respectively.

Review of Margins Needed to Develop Fatigue Design Curves From Laboratory Test Data

2003 ◽  
Author(s):  
W. A. Van Der Sluys
Keyword(s):  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Light Water Reactor ◽  
Fatigue Properties ◽  
Low Alloy Steels ◽  
Test Results ◽  
Cycle Fatigue ◽  
Fatigue Design ◽  
Current Design ◽  
Alloy Steels

The PVRC has just completed a review of the effect of LWR (Light Water Reactor) coolant environment on the low cycle fatigue properties of carbon and low alloy steels. The PVRC has made recommendations to the ASME on changes to the boiler and pressure vessel codes to account for the environmental effects. In developing the recommendations, the margins used to produce the design curves from fatigue test results of laboratory specimens, were studied. This paper describes the margins used by the ASME in the development of the current design curves and discusses what margins should be applied when the laboratory fatigue testing includes tests in simulated LWR coolant environments.

The influence of nitrogen on the oxidation resistance of low alloy steels

1980 ◽  
Vol 295 (1413) ◽  
pp. 336-336
Keyword(s):  
Surface Layer ◽  
Mild Steel ◽  
Oxidation Resistance ◽  
Nitrided Layer ◽  
Low Alloy Steels ◽  
Fine Grain ◽  
Nucleation Sites ◽  
Alloy Steels ◽  
Nitrided Surface ◽  
Cyclic Changes

Experiments in simulated boiler flue gas have shown that the oxidation resistance of mild steel is increased by up to two orders of magnitude by a surface nitriding treatment. Oxidation resistance was determined under isothermal conditions and during cyclic changes of temperature and oxygen potential. The oxide scale has a fine grain size, is extremely adherent and is therefore protective. A nitrided surface layer is produced by gas-metal equilibration with NH 3 : H 2 gas mixtures under conditions to form austenite (y) at nitriding temperature. On cooling to room temperature, martensite (a') is formed with retained austenite, the relative proportions of which depend on cooling rate. During oxidation at 420 °C, martensite and austenite in the immediate surface layer temper within a few minutes to form ferrite (a) containing a fine dispersion of y'-Fe 4 N platelets ca . 50 nm in diameter. X-ray analysis at increasing depth from the surface of nitrided mild steel shows that tempering of the a' + y structure to a + y'-Fe 4 N is accelerated at the free surface of the alloy relative to the remainder of the nitrided layer, and results in formation of incoherent nitride precipitates on the surface. The nitride particles act as nucleation sites for oxide formation, and electron microscopy shows that the oxide nuclei are of the same order of size as the nitride particles.

THE ANALYSIS OF THE INFLUENCE OF LASER HEAT TREATMENT OF THE CRANKSHAFT JOURNAL ON WEAR RESISTANCE OF THE BEARING

Tribologia ◽  
2016 ◽  
Vol 266 (2) ◽  
pp. 87-100 ◽  
Author(s):  
Marta PACZKOWSKA
Keyword(s):  
Wear Resistance ◽  
Surface Layer ◽  
Laser Treatment ◽  
Friction Pair ◽  
Rapid Change ◽  
Wear Test ◽  
Test Results ◽  
Test Load ◽  
Wear Process ◽  
Stabilization Period

The aim of the presented research was to evaluate wear effects of bearing elements in case of modification based on laser alloying with boron of journal surface layer. The research was performed on ZPG-IV tribology tester with journal-bearing friction pair. During the test load was applied progressively. SEM microscopes and non-contact 3D optical profilografometr was used to assess the test results. Study of the character of the wear process allowed to state, that after each increase of load during the test, rapid change of the value of oil temperature and the value of resistance in journal-pan contact was appeared. Then, the stabilization period was followed by. Some differences in the way of those processes between tested variants were noticed. Firstly, during the stabilization period larger thickness of the oil film at the journal-pan interface was notice in case of journal after laser treatment than in case of untreated journal. Secondly, it could be expected that oil temperature will be lower in case of longer time of tribological test for treated journal (than for untreated journal). It should favor better wear resistance of this kinematic node. Macro and microscopic observations of both types of surface after wear test allow to state, that journals after laser treatment were characterized by less wear effects, as cavities in the surface layer in comparison to untreated journals. More intensive wear of journals without treatment was confirmed by stereometric research and measurements of surface roughness parameters. This research allow to state positive laser treatment influence on the wear resistance of the journal. Although, there was no larger loss of the surface layer in case of pans after cooperation with hard journal after laser treatment (describe by the decrease of pans’ thickness) then loss of the surface layer in case of pans after cooperation with softer untreated journal (nearly 5-times softer than the surface layer of treated journal), the microscopic observations and measurement of the parameters of stereometric structure of their surface showed more intensive wear of pan after cooperation with treated journal.

Review and Consideration of Unsettled Problems on Evaluation of Fatigue Damage in LWR Water

2005 ◽  
Author(s):  
Makoto Higuchi ◽  
Katsumi Sakaguchi
Keyword(s):  
Fatigue Life ◽  
Mechanical Test ◽  
Low Alloy Steels ◽  
Test Results ◽  
Considerable Effort ◽  
Test Conditions ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Fatigue Life Reduction ◽  
Year 2000

Reduction in the fatigue life reduction of structural materials of nuclear components in LWR water was initially detected and examined by the authors in the 1980s, who subsequently directed considerable effort to the development of a method for evaluating this reduction quantitatively. Following the establishment of equations to calculate environmental fatigue life reduction for carbon and low alloy steels in 1985 by Higuchi and Sakamoto [1], appeared based on numerous new fatigue data obtained under various environmental and mechanical test conditions. The latest models for evaluation using Fen of the environmental fatigue life correction factor were proposed for carbon and low alloy steels in the year 2000 and for austenitic stainless steel, in 2002. Fen depends on some essential variables such as material, strain rate, temperature, dissolved oxygen and sulfur concentration in steel. The equation for determining Fen is given by each parameter for each material. These models, having been developed three to five years ago, should be properly revised based on new test results. This paper reviews and discusses five major topics pertinent to such revision.

M3C and M7C3 Carbide Precipitation in Modified H11 Tool Steel

2011 ◽  
Vol 172-174 ◽  
pp. 414-419 ◽  
Author(s):  
Rafael Agnelli Mesquita ◽  
Hans Jürgen Kestenbach
Keyword(s):  
Tool Steel ◽  
High Energy ◽  
Carbide Formation ◽  
Low Alloy Steels ◽  
Tool Steels ◽  
High Alloy ◽  
Particle Distributions ◽  
Alloy Tool ◽  
Alloy Steels ◽  
Means Of Transmission

Recent modifications in chemical composition have been applied commercially to high alloy tool steels, using different combinations of Cr, Si and Mo contents. Several reports have been published in the literature about the effects of such modifications on mechanical properties and tool performance, but only a few of these studies were concerned with the effects on secondary carbide formation. In previous papers, improvements in toughness and tempering resistance that were found in a 5% Cr tool steel (type H11 with lower Si contents) have been attributed to particular distributions of Cr-rich M7C3particles. Although M7C3carbides have been studied extensively in low alloy steels, some important differences have now been observed by the present authors for high alloy tool steels, especially regarding the effects of Si and Cr. The present work is concerned with the formation of Cr-rich M7C3as well as Fe-rich M3C particles in modified H11 tool steels, discussing the precipitation sequence and particle distributions developed during tempering within the martensite microstructure. By means of transmission electron microscopy, the effect of Si on M3C cementite formation has been found to be responsible for a substantial change in the distribution of the M7C3carbide phase, leading to a concentration of these particles at high energy interfaces in interlath and interpackage regions.

Effects of cooling rate on the mechanical properties of dual phase treated vanadium steels

1983 ◽  
Vol 41 ◽  
pp. 220-221
Author(s):  
L.J. Chen ◽  
H.C. Cheng ◽  
J.R. Gong ◽  
J.G. Yang
Keyword(s):  
Mechanical Properties ◽  
Cooling Rate ◽  
Automobile Industry ◽  
High Strength ◽  
Weight Percent ◽  
Low Alloy Steels ◽  
Dual Phase ◽  
Resource Requirement ◽  
Alloy Steels ◽  
Potential Weight

For fuel savings as well as energy and resource requirement, high strength low alloy steels (HSLA) are of particular interest to automobile industry because of the potential weight reduction which can be achieved by using thinner section of these steels to carry the same load and thus to improve the fuel mileage. Dual phase treatment has been utilized to obtain superior strength and ductility combinations compared to the HSLA of identical composition. Recently, cooling rate following heat treatment was found to be important to the tensile properties of the dual phase steels. In this paper, we report the results of the investigation of cooling rate on the microstructures and mechanical properties of several vanadium HSLA steels.The steels with composition (in weight percent) listed below were supplied by China Steel Corporation: 1. low V steel (0.11C, 0.65Si, 1.63Mn, 0.015P, 0.008S, 0.084Aℓ, 0.004V), 2. 0.059V steel (0.13C, 0.62S1, 1.59Mn, 0.012P, 0.008S, 0.065Aℓ, 0.059V), 3. 0.10V steel (0.11C, 0.58Si, 1.58Mn, 0.017P, 0.008S, 0.068Aℓ, 0.10V).

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