Effect of transformation plasticity on residual stress fields in laser surface hardening treatment

1991 ◽  
Vol 9 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Y. -S. Yang ◽  
S. -J. Na
Keyword(s):  
Residual Stress ◽  
Surface Hardening ◽  
Laser Surface ◽  
Stress Fields ◽  
Transformation Plasticity ◽  
Laser Surface Hardening ◽  
Hardening Treatment

A complete residual stress model for laser surface hardening of complex medium carbon steel components

2016 ◽  
Vol 302 ◽  
pp. 100-106 ◽  
Author(s):  
Erica Liverani ◽  
Adrian H.A. Lutey ◽  
Alessandro Ascari ◽  
Alessandro Fortunato ◽  
Luca Tomesani
Keyword(s):  
Residual Stress ◽  
Carbon Steel ◽  
Surface Hardening ◽  
Medium Carbon Steel ◽  
Laser Surface ◽  
Complex Medium ◽  
Stress Model ◽  
Medium Carbon ◽  
Laser Surface Hardening

Local Residual Stress Distributions Induced by Repeated Austenite-Martensite Transformation via Laser Surface Hardening of Steel AISI 4140

2011 ◽  
Vol 681 ◽  
pp. 321-326 ◽  
Author(s):  
Vladimir Kostov ◽  
Jens Gibmeier ◽  
Alexander Wanner
Keyword(s):  
Residual Stress ◽  
Surface Hardening ◽  
Laser Pulses ◽  
Inert Atmosphere ◽  
Laser Surface ◽  
Stress Distributions ◽  
Depth Direction ◽  
Laser Surface Hardening ◽  
Aisi 4140 ◽  
Martensite Transformations

The effects of laser surface hardening of steel samples on the microstructure and residual stresses were determined for single as well as multiple laser pulses. Samples made of steel grade AISI 4140 were hardened by means of a high-power diode laser (HPDL) system using either single or multiple laser pulses resulting in single as well as repeated austenite-martensite transformations. The hardening was carried out in a specially designed process chamber allowing laser surface treatment in inert atmosphere in order to avoid oxide scale formation. The residual stress distributions in lateral and in depth direction were analysed by means of X-ray diffraction for samples hardened by up to 27 laser pulses. Residual stress analyses were carried out by means of the sin²y- method. The results indicate the extension of the hardened zone in lateral and in depth direction with an increase in the number of applied laser pulses. This evolution is connected with significant changes in the local residual stress distributions.

scholarly journals Comparison of Wear Performance of Austempered and Quench-Tempered Gray Cast Irons Enhanced by Laser Hardening Treatment

2020 ◽  
Vol 10 (9) ◽  
pp. 3049
Author(s):  
Bingxu Wang ◽  
Gary C. Barber ◽  
Rui Wang ◽  
Yuming Pan
Keyword(s):  
Heat Treatment ◽  
Cast Iron ◽  
Surface Hardening ◽  
Gray Cast Iron ◽  
High Hardness ◽  
Laser Surface ◽  
Gray Cast ◽  
Wear Loss ◽  
Laser Surface Hardening ◽  
Hardening Treatment

The current research studied the effects of laser surface hardening treatment on the phase transformation and wear properties of gray cast irons heat treated by austempering or quench-tempering, respectively. Three austempering temperatures of 232 °C, 288 °C, and 343 °C with a constant holding duration of 120 min and three tempering temperatures of 316 °C, 399 °C, and 482 °C with a constant holding duration of 60 min were utilized to prepare austempered and quench-tempered gray cast iron specimens with equivalent macro-hardness values. A ball-on-flat reciprocating wear test configuration was used to investigate the wear resistance of austempered and quench-tempered gray cast iron specimens before and after applying laser surface-hardening treatment. The phase transformation, hardness, mass loss, and worn surfaces were evaluated. There were four zones in the matrix of the laser-hardened austempered gray cast iron. Zone 1 contained ledeburite without the presence of graphite flakes. Zone 2 contained martensite and had a high hardness, which was greater than 67 HRC. Zone 4 was the substrate containing the acicular ferrite and carbon-saturated austenite with a hardness of 41–27 HRC. In Zone 3, the substrate was tempered by the low thermal radiation. For the laser-hardened quench-tempered gray cast iron specimens, three zones were observed beneath the laser-hardened surface. Zone 1 also contained ledeburite, and Zone 2 was full martensite. Zone 3 was the substrate containing the tempered martensite. The tempered martensite became coarse with increasing tempering temperature due to the decomposition of the as-quenched martensite and precipitation of cementite particles. In the wear tests, the gray cast iron specimens without heat treatment had the highest wear loss. The wear performance was improved by applying quench-tempering heat treatment and further enhanced by applying austempering heat treatment. Austempered gray cast iron specimens had lower mass loss than the quench-tempered gray cast iron specimens, which was attributed to the high fracture toughness of acicular ferrite and stable austenite. After utilizing the laser surface hardening treatment, both austempered and quench-tempered gray cast iron specimens had decreased wear loss due to the high surface protection provided by the ledeburitic and martensitic structures with high hardness. In the worn surfaces, it was found that cracks were the dominant wear mechanism. The results of this work have significant value in the future applications of gray cast iron engineering components and provide valuable references for future studies on laser-hardened gray cast iron.

Laser Surface Hardening of Steel: Effect of Process Atmosphere on the Microstructure and Residual Stresses

2013 ◽  
Vol 772 ◽  
pp. 149-153 ◽  
Author(s):  
Vladimir Kostov ◽  
Jens Gibmeier ◽  
Alexander Wanner
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Surface Hardening ◽  
Local Heating ◽  
Laser Surface ◽  
Inert Gas ◽  
X Ray ◽  
Depth Direction ◽  
Laser Surface Hardening ◽  
Gas Atmosphere

The effect of processing atmosphere on the microstructure and residual stresses are studied for laser surface hardening on steel samples of grade AISI 4140. Samples were hardened in air, vacuum and inert gas atmosphere (Helium) by means of a stationary laser beam. A high-power diode laser (HPDL) system was used in combination with a custom-designed process chamber. Residual stress distributions in lateral and in depth direction were analysed after laser processing by means of X-ray diffraction according to the well known sin² - method. X-ray residual stress analyses were supplemented by microscopic investigations of the local microstructure. The results indicate a widening of the compressive stressed region in lateral as well as in depth direction by surface hardening in inert gas atmosphere compared to laser surface hardening in air or vacuum atmosphere. This is due to the local heating flux distribution during the laser assisted heat treatment which is strongly affected by the processing atmosphere an leads to an extension of the hardening zone when using helium as inert gas.

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