scholarly journals Bionic Repair of Thermal Fatigue Cracks in Ductile Iron by Laser Melting with Different Laser Parameters

Metals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 101 ◽  
Author(s):  
Siyuan Ma ◽  
Ti Zhou ◽  
Hong Zhou ◽  
Geng Chang ◽  
Benfeng Zhi ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Ductile Iron ◽  
Laser Energy ◽  
Fatigue Cracks ◽  
Fatigue Cracking ◽  
Unit Distance ◽  
Thermal Fatigue Resistance ◽  
Brake Discs ◽  
Thermal Fatigue Cracks

Nodular iron brake discs typically fail due to serious thermal fatigue cracking, and the presence of graphite complicates the repair of crack defects in ductile iron. This study presents a novel method for remanufacturing ductile iron brake discs based on coupled bionics to repair thermal fatigue cracks discontinuously using bio-inspired crack blocking units fabricated by laser remelting at various laser energy inputs. Then, the ultimate tensile force and thermal fatigue crack resistance of the obtained units were tested. The microhardness, microstructure, and phases of the units were characterized using a digital microhardness meter, optical microscopy, scanning electron microscopy, and X-ray diffraction. It was found that the units without defects positively impacted both the thermal fatigue resistance and tensile strength. The unit fabricated at a laser energy of 165.6 − 15 + 19 J/ mm 2 had sufficient depth to fully close the crack, and exhibited superior anti-cracking and tensile properties. When the unit distance is 3 mm, the sample has excellent thermal fatigue resistance. In addition, the anti-crack mechanism of the units was analysed.

Improvement of Thermal Fatigue Resistance of A Wrought Nickel-Base Superalloy by Laserglaze

1985 ◽  
Vol 58 ◽  
Author(s):  
Zhao Qi ◽  
Ge Yunlong ◽  
Hu Zhuangqi ◽  
Jiang Ming ◽  
Shih Changshu
Keyword(s):  
Heat Treatment ◽  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Fatigue Cracks ◽  
Nickel Base Superalloy ◽  
Post Heat Treatment ◽  
Thermal Fatigue Resistance ◽  
Nickel Base ◽  
Thermal Fatigue Cracks ◽  
Base Superalloy

ABSTRACTLaserglaze with appropriate post heat treatment has improved the thermal fatigue resistance of a wrought nickel-base superalloy. It was found that laserglaze was able to eliminate the blocky MC phase, refine grains and form a very interesting microstructure of serrated grain boundaries. Careful selection of post heat treatment markedly increased the strength in the laser irradiated region. The initiation and propagation of thermal fatigue cracks were suppressed by this novel microstructure.

A New Method to Study the Thermal Fatigue Resistance of Molybdenum by High Power Laser Irradiation

2012 ◽  
Vol 184-185 ◽  
pp. 1384-1388 ◽  
Author(s):  
Shuai Lu ◽  
Hong Wei Li ◽  
Dun Bo Yu ◽  
Ming Pang ◽  
Bo Wang
Keyword(s):  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
High Power ◽  
Laser Heating ◽  
Fatigue Cracks ◽  
Crack Density ◽  
Scale Production ◽  
High Power Laser ◽  
Power Laser ◽  
Thermal Fatigue Resistance

In single roll rapid quenching molding, especially for the preparation of amorphous ribbons and rare earth permanent magnetic materials, the chilling roll is an extremely important component of the preparation equipment. However, frequent repair of the roll is not conducive to continuous large-scale production because of its poor thermal fatigue resistance. Molybdenum is gradually being used as chilling roll material in some applications, and in the present paper a new approach to study the thermal fatigue resistance of molybdenum is based on laser pulse irradiation on the molybdenum surface. A new designed device effectively prevents the molybdenum to be oxidized during the laser heating test. The experiments of thermal fatigue damage on molybdenum were conducted by the high power laser. The results shows that the fatigue cracks had been propagated in the irradiated region after the specimen was loaded by 200 times pulsed laser heating. There is a greater crack density in the laser heating brim region than in the center of the irradiated region. According to the transgranular mode of crack propagation in the laser heating brim region and intergranular mode in the center of the irradiated region, the maximum stress took place at the intersection region due to the great temperature gradient in the laser heating brim region. Continued basis-oriented experiments are planned, regarding the mechanism of thermal fatigue crack initiation and propagation for chilling roll materials.

Study on the Thermal Fatigue Resistance of Ductile Iron

2012 ◽  
Vol 512-515 ◽  
pp. 2093-2096
Author(s):  
Zhang Yin Xu ◽  
Yin Ju Jiang
Keyword(s):  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Ductile Iron ◽  
Service Condition ◽  
Nodular Cast Iron ◽  
Temperature Cycle ◽  
Matrix Structure ◽  
Thermal Fatigue Resistance ◽  
Aluminum Ingot ◽  
Bainitic Structure

Simulated service condition of aluminum ingot casting molds, samples of ductile iron was tested in a temperature Cycle from750°C and water-cooled to 25°C till a crack appeared in the sample. its thermal fatigue resistance of samples based various microstructure included as—casting, annealing or alloying ferritic matrix structure, or alloying pearlitic structure and the upper or low the bainitic structure had been researched. The study shows that the thermal fatigue resistance of the annealing ferritic nodular cast iron was superior to the others.

Thermal Fatigue Studies Using HF Induction Heating of Die Materials for Light Metals Casting

2009 ◽  
Vol 618-619 ◽  
pp. 357-360 ◽  
Author(s):  
Stefan Gulizia ◽  
Darryl Jones ◽  
Mahnaz Z. Jahedi ◽  
Trevor Kearney ◽  
Paul Koltun
Keyword(s):  
Induction Heating ◽  
Thermal Fatigue ◽  
Fatigue Cracks ◽  
Fatigue Cracking ◽  
Net Energy ◽  
Crack Morphology ◽  
Die Materials ◽  
Die Material ◽  
Thermal Fatigue Cracks ◽  
Hot Work Tool Steels

In this study a new thermal fatigue test rig has been developed that can apply a net energy input to materials with different physical properties using HF induction heating. Several commercially available hot work ferrous and non-ferrous die materials were evaluated with the aim of providing a basis for selecting an appropriate die material with good thermal fatigue resistance for a given HPDC application. The results show materials with high thermal conductivity such as tungsten-based materials are more resistant to thermal fatigue cracking than conventionally used hot work tool steels for HPDC dies. The initiation and growth of thermal fatigue cracks were examined and periodically evaluated using computer image analysis, for crack morphology, and hardness on each material tested.

Effect of Vanadium on Thermal Fatigue Resistance of Cr5 Deposited Metal

2012 ◽  
Vol 512-515 ◽  
pp. 1892-1900
Author(s):  
Qing Bao Wang ◽  
Zhuo Xin Li ◽  
Yao Wu Shi ◽  
Jing Xiao
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Crack Length ◽  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Fatigue Cracks ◽  
Vanadium Content ◽  
Thermal Fatigue Resistance ◽  
Deposited Metal ◽  
High Temperature Tensile

In the present work, effect of vanadium on mechanical and thermal fatigue resistance of Cr5 deposited metal is investigated. It is found that hard phases with rich vanadium are mainly distributed at grain boundaries. Vanadium affects the high temperature tensile strength and thermal fatigue cracking obviously. With the increase of vanadium content, high temperature tensile strength of deposited metals shows a initial rise up, then drop for more than 0.54 wt.% V. Toughness and high temperature plasticity are increased up to 0.26 wt.% V, then drop up to 0.89 wt.% V, then toughness and plasticity increase again. Moreover, the thermal fatigue crack length shows a initial decrease up to 0.26 wt. % V, then slightly rise up for 0.89 wt.% V, then crack length shorten again. It is expected that the optimal vanadium content is in a range of 0.18~0.26 wt.% for resisting the thermal crack growth. Fractographic observation shows that the thermal fatigue cracks mainly are transgranular growth. It is felt that the crack length is closely related to microstructure, oxidation resistance, toughness and high temperature plasticity of the deposited alloy

THERMO-SPAN ALLOY

Alloy Digest ◽  
1994 ◽  
Vol 43 (2) ◽  
Keyword(s):  
Physical Properties ◽  
Tensile Properties ◽  
Fatigue Resistance ◽  
Thermal Fatigue ◽  
Rupture Strength ◽  
Stress Rupture ◽  
Heat Treating ◽  
Thermal Fatigue Resistance ◽  
Stress Rupture Strength

Abstract THERMO-SPAN ALLOY is a precipitation-hardenable superalloy with a low coefficient of expansion combined with tensile and stress-rupture strength. Thermal fatigue resistance is inherent. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as creep. It also includes information on forming and heat treating. Filing Code: FE-105. Producer or source: Carpenter.

Assessment of thermal behavior of a cooling system to reduce thermal fatigue cracks in aluminum injection molds

2020 ◽  
pp. 75-86
Author(s):  
Sergio Antonio Camargo ◽  
Lauro Correa Romeiro ◽  
Carlos Alberto Mendes Moraes
Keyword(s):  
Thermal Fatigue ◽  
Cooling System ◽  
Fatigue Cracks ◽  
Cooling Water ◽  
Thermal Conditions ◽  
Thermal Gradients ◽  
Ansys Software ◽  
Cooling Systems ◽  
Thermal Fatigue Cracks ◽  
Number Of Cycles

The present article aimed to test changes in cooling water temperatures of males, present in aluminum injection molds, to reduce failures due to thermal fatigue. In order to carry out this work, cooling systems were studied, including their geometries, thermal gradients and the expected theoretical durability in relation to fatigue failure. The cooling system tests were developed with the aid of simulations in the ANSYS software and with fatigue calculations, using the method of Goodman. The study of the cooling system included its geometries, flow and temperature of this fluid. The results pointed to a significant increase in fatigue life of the mold component for the thermal conditions that were proposed, with a significant increase in the number of cycles, to happen failures due to thermal fatigue.

Heat Resistance of Ferritic Stainless Steels with 15% Chromium for Automobile Exhaust System

2011 ◽  
Vol 239-242 ◽  
pp. 1799-1803
Author(s):  
Hua Bing Li ◽  
Zhou Hua Jiang ◽  
Qi Feng Ma ◽  
Dong Ping Zhan
Keyword(s):  
High Temperature ◽  
Grain Boundaries ◽  
Thermal Fatigue ◽  
Fatigue Cracks ◽  
Exhaust System ◽  
High Temperature Strength ◽  
Temperature Oxidation ◽  
Ferritic Stainless Steels ◽  
Automobile Exhaust ◽  
Thermal Fatigue Cracks

The high-temperature strength and thermal fatigue properties of Fe-Cr-Nb-Mo ferritic stainless steel (FSSNEW) developed for automobile exhaust system were investigated. The results show that the high-temperature tensile strength and yield strength of FSSNEW are better than or equal to those of the presently applied ferritic stainless steels. The thermal fatigue cracks nucleate at the V-notch. The inclusions along grain boundaries become prior regions for initiation of the cracks. The inclusions distributed at the defects make the formation of cracks in the materials easily through the effects of cycle thermal stress and thermal strain. The length and propagated rate of thermal fatigue cracks increase with the maximum tested temperature increasing. When the maximum temperature arrives at 900°C, the high-temperature oxidation is serious along the grain boundaries, which aggravates the cracks propagating along the grain boundaries. The principle mechanism of stress assisted grain boundary oxygen (SAGBO) embrittlement can be applied to illustrate the effects of external stress on aggravating the damage caused by environmental factors. Therefore, the high-temperature oxidation is the main reason for the propagation of thermal fatigue cracks. The FSSNEW is satisfied for the applied requirement of high-temperature strength in the hot side of the automobile exhaust system.

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