Fatigue Characteristics of Laser Surface-Hardened Cast Irons

1987 ◽  
Vol 109 (3) ◽  
pp. 179-187 ◽  
Author(s):  
P. A. Molian
Keyword(s):  
Continuous Wave ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Case Depth ◽  
Laser Surface ◽  
Low Alloy Steels ◽  
Surface Layers ◽  
Cast Irons ◽  
Co2 Gas ◽  
Alloy Steels

Contrary to expectations, laser surface heat treatment has a deleterious effect on the fatigue performance of pearlitic gray and ductile cast irons. A 1.2 kW, continuous wave, CO2 gas laser, operating in square beam mode, was employed to heat-treat the surfaces of standard fatigue specimens. Rotational-bending fatigue tests were then conducted on untreated (as-cast) and laser treated specimens. Results indicated that the effect on fatigue behavior of case depth, microstructure and hardness of laser-hardened surface layers were opposite to that observed in carbon and low alloy steels. A fracture model based on the presence of graphite, residual stresses, and strain-induced transformation is postulated to explain the adverse effect of laser hardening of cast irons.

Wear Behavior of Laser Surface-Hardened Gray and Ductile Cast Irons: Part 1—Sliding Wear

1986 ◽  
Vol 108 (3) ◽  
pp. 326-333 ◽  
Author(s):  
P. A. Molian ◽  
Mark Baldwin
Keyword(s):  
Sliding Wear ◽  
Continuous Wave ◽  
Wear Behavior ◽  
Test System ◽  
Case Depth ◽  
Laser Surface ◽  
Dramatic Improvement ◽  
Cast Irons ◽  
Severe Wear ◽  
Depth Analysis

The influence of laser surface transformation hardening on the sliding wear characteristics and mechanisms of ASTM class-40 gray and 80-55-06 ductile cast irons was investigated. A 1.2 kw, continuous wave, CO2 gas laser was employed to scan the beam successively across the surfaces of cast irons to generate hardened and tempered layers with various case depths. A pin-on-disk wear test system was then used to study the wear behavior as functions of case depth, microstructure, hardness, and surface roughness. As expected, a dramatic improvement in resistance to scuffing and sliding wear was obtained. However, the most significant result was the occurrence of negligible oxidational wear for a load range that increased with an increase in case depth. Resistance to mild and severe wear, mild-to-severe wear transition load, and frictional heating were increased with an increase in case depth. Analysis of worn surfaces and wear debris revealed that negligible oxidational wear in laser-hardened irons is due to two mechanisms: oxidation and adhesion of oxide to the substrate. In contrast, the mild oxidational wear of untreated irons occurs through the formation of loose oxide debris. The mechanisms of severe wear were plastic deformation, delamination, and adhesion; the rate process was controlled by adhesion for laser hardened irons and delamination for untreated irons.

Fatigue Behavior of Nuclear Materials Under Air and Environmental Conditions

2013 ◽  
Author(s):  
Karl-Heinz Herter ◽  
Xaver Schuler ◽  
Thomas Weissenberg
Keyword(s):  
Thermal Loading ◽  
Low Cycle Fatigue ◽  
Fatigue Behavior ◽  
Austenitic Stainless Steels ◽  
Cyclic Stress ◽  
Fatigue Tests ◽  
Crack Growth Behavior ◽  
Low Alloy Steels ◽  
Cycle Fatigue ◽  
Alloy Steels

The assessment of fatigue and cyclic crack growth behavior of safety relevant components is of importance for ageing management with regard to safety and reliability. For cyclic stress evaluation different codes and standards provide fatigue analysis procedures to be performed considering the various mechanical and thermal loading histories and geometric complexities of the components. For the fatigue design curves used as limiting criteria the influence of different factors like e.g. environment, surface finish and temperature must be taken into consideration in an appropriate way. Fatigue tests were performed in the low cycle fatigue and high cycle fatigue regime with low-alloy steels as well as with Nb- and Ti-stabilized German austenitic stainless steels in an air and high temperature BWR environment to extend the state of knowledge of environmentally assisted fatigue as it can occur in BWR plants. Using the RPV steel 22NiMoCr3-7 experimental data was developed to verify the influence of BWR coolant environment (high purity water as well as water containing sulphate with 90 ppb SO4 and water containing chloride with 50 ppb Cl at a test temperature of 240 °C and an oxygen content of 400 ppb) on the fatigue life and to extend the basis for a reliable estimation of the remaining service life of reactor components. Corresponding experiments in air were performed to establish reference data to determine the environmental correction factor Fen. The experimental results are compared with available international mean data curves, the new design curves and on the basis of the environmental factor Fen.

Development of New Design Fatigue Curves in Japan: Proposal of a New Fatigue Evaluation Method

2018 ◽  
Author(s):  
Seiji Asada ◽  
Akihiko Hirano ◽  
Toshiyuki Saito ◽  
Yasukazu Takada ◽  
Hideo Kobayashi
Keyword(s):  
Stainless Steels ◽  
Evaluation Method ◽  
Austenitic Stainless Steels ◽  
Fatigue Tests ◽  
Carbon Steels ◽  
Low Alloy Steels ◽  
Stress Effect ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Fatigue Evaluation

In order to develop new design fatigue curves for carbon steels & low-alloy steels and austenitic stainless steels and a new design fatigue evaluation method that are rational and have clear design basis, Design Fatigue Curve (DFC) Phase 1 subcommittee and Phase 2 subcommittee were established in the Atomic Energy Research Committee in the Japan Welding Engineering Society (JWES). The study on design fatigue curves was actively performed in the subcommittees. In the subcommittees, domestic and foreign fatigue data of small test specimens in air were collected and a comprehensive fatigue database (≈6000 data) was constructed and the accurate best-fit curves of carbon steels & low-alloy steels and austenitic stainless steels were developed. Design factors were investigated. Also, a Japanese utility collaborative project performed large scale fatigue tests using austenitic stainless steel piping and low-alloy steel flat plates as well as fatigue tests using small specimens to obtain not only basic data but also fatigue data of mean stress effect, surface finish effect and size effect. Those test results were provided to the subcommittee and utilized the above studies. Based on the above studies, a new fatigue evaluation method has been developed.

Study on Thermal Fatigue Resistance of Non-Smooth Cast Iron Treated by Laser Surface Alloying of CrNi Powders

2011 ◽  
Vol 291-294 ◽  
pp. 1405-1411
Author(s):  
Tong Xin ◽  
Zhou Hong ◽  
Liu Min
Keyword(s):  
Cast Iron ◽  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Fatigue Behavior ◽  
Laser Surface ◽  
Surface Alloying ◽  
Laser Melting ◽  
Cast Irons ◽  
Laser Surface Alloying ◽  
Thermal Fatigue Resistance

The past studies indicated that thermal fatigue resistance of cast irons could be improved by partly laser melting treatment. However the only disadvantage of this technology is that the enhancement of thermal fatigue resistance would be limited because of the fixed chemical composition of sample matrix. For this purpose, the laser surface alloying of CrNi was selected for changing both the compositions and the microstructures of laser treated zone, and the effects of alloy powder compositions on thermal fatigue behavior were also investigated in this paper. The results indicate that the alloy elements distribute homogeneously, and their contents increase markedly in the non-smooth unit on the alloyed layer. The non-smooth unit is strengthened further compared with laser melting treatment. Thermal fatigue resistance of cast iron is enhanced evidently by laser surface alloying of CrNi powders, and for all samples tested, those treated with 25%Cr-75%Ni powders have the best thermal fatigue resistance.

scholarly journals Experimental and numerical investigation of the overload effect on fatigue behaviour of spot-welded steel sheets

2018 ◽  
Vol 106 (3) ◽  
pp. 309 ◽  
Author(s):  
Fabienne Pennec ◽  
Bianzeubé Tikri ◽  
Sébastien Bergamo ◽  
Michel Duchet ◽  
Bastien Weber ◽  
...  
Keyword(s):  
Failure Modes ◽  
Hsla Steel ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Fatigue Tests ◽  
Favourable Effect ◽  
Low Alloy Steels ◽  
Element Analysis ◽  
Alloy Steels ◽  
Spot Welded

Spot-weld joints are commonly used to fasten together metal sheets in automotive industry. The car frame used in Renault vehicles is a representative example of the usefulness of this method. Most of the spot-welds experience fatigue damaging occurrence due to rough roads or driving conditions which apply periodical overloads to the vehicle. Understanding their fatigue behaviour is crucial from the viewpoint of failure prevention in design. In this study, a series of experiments was conducted to study the fatigue failure of spot-welded tensile-shear specimens made of a deep-drawing steel (XES) and High strength low alloy steels (HE360D and XE360D). Two different types of fatigue tests were performed, the first one with a constant-amplitude sinusoidal loading (loading ratio equal to 0.1) and the second one with one incidental overload cycle introduced per 100 cycles. The experimental results show a favourable effect of overloads for HSLA steel specimens, whereas the effect is the opposite for XES steel specimens. A finite element analysis was carried out using the open-source Salome-Meca platform to determine the stress states within the specimens around the weld spot and explains both failure modes observed on the specimens at high and low loads.

Development of New Design Fatigue Curves in Japan: Discussion of Best Fit Curves Based on Fatigue Test Data With Large Scale Piping

2018 ◽  
Author(s):  
Masaru Bodai ◽  
Yuichi Fukuta ◽  
Seiji Asada ◽  
Kentaro Hayashi
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Large Scale ◽  
Fatigue Tests ◽  
Carbon Steels ◽  
Surface Finishing ◽  
Low Alloy Steels ◽  
Fatigue Data ◽  
Alloy Steels ◽  
Best Fit

In order to develop new design fatigue curves for austenitic carbon steels & low alloy steels and stainless steels and a new design fatigue evaluation method that are rational and have clear design basis, Design Fatigue Curve (DFC) Phase 1 subcommittee and Phase 2 subcommittee were established in the Atomic Energy Research Committee in the Japan Welding Engineering Society. The study on design fatigue curves was actively performed in the subcommittees. In the subcommittees, domestic and foreign fatigue data of small test specimens in air were collected and a comprehensive fatigue database was constructed. Using this fatigue database, the accurate best-fit curves of austenitic carbon steels & low alloy steels and stainless steels were developed by applying tensile strength to a parameter of the curve. Regarding design factors on design fatigue curves, data scatter, mean stress correction, surface finishing effect, size effect and variable loading effect were investigated and each design factor was decided to be individually considered on the design fatigue curves. A Japanese utility project performed large scale fatigue tests using austenitic stainless steel piping and carbon and low-alloy steel flat plates as well as fatigue tests using small specimens to obtain not only basic data but also fatigue data of mean stress effect and surface finishing effect. Those test results were provided to the subcommittee and utilized the above studies. In this paper, the large scale fatigue tests using austenitic stainless steel piping and the best-fit curve of austenitic stainless steel are discussed.

Effect of Surface Hardening Technique and Case Depth on Rolling Contact Fatigue Behavior of Alloy Steels

2014 ◽  
Vol 58 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Lechun Xie ◽  
David Palmer ◽  
Frederick Otto ◽  
Zhanjiang Wang ◽  
Q. Jane Wang
Keyword(s):  
Surface Hardening ◽  
Fatigue Behavior ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Case Depth ◽  
Rolling Contact ◽  
Alloy Steels ◽  
Effect Of Surface
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