Laser Heat Treatment of Cast Irons—Optimization of Process Variables, Part II

1986 ◽  
Vol 108 (3) ◽  
pp. 233-239 ◽  
Author(s):  
P. A. Molian ◽  
A. K. Mathur
Keyword(s):  
Gaussian Beam ◽  
Laser Power ◽  
Thermal Response ◽  
Rate Distortion ◽  
Theoretical Models ◽  
Gray Iron ◽  
Case Depth ◽  
Coverage Rate ◽  
Cast Irons ◽  
Heat Treated

ASTM class 40 gray and 80-55-06 ductile cast irons were surface heat-treated by a 1.2-kW, CO2 laser to study the effects of square and oscillating-gaussian beam modes on case depth, coverage rate, distortion, hardness, and microstructure. The results were compared with that of ring and gaussian beam modes, which were described in Part I. Square and oscillating beams maximized case depth and coverage rate, while ring and gaussian beams minimized distortion. Hardness and microstructure of heat-treated layers were unaffected by the beam mode. For given laser parameters, ductile iron always exhibited larger case depth and coverage rate than gray iron because of the lower thermal diffusivity. Experimental data and theoretical models indicated that thermal response of a material to laser power cannot be described by a simple function as given by heat conduction models and that the best correlating factor for case depth is P/V (P is laser power, V is scan rate).

Wear Behavior of Laser Surface-Hardened Gray and Ductile Cast Irons. Part 2—Erosive Wear

1988 ◽  
Vol 110 (3) ◽  
pp. 462-466 ◽  
Author(s):  
P. A. Molian ◽  
Mark Baldwin
Keyword(s):  
Erosion Rate ◽  
Continuous Wave ◽  
Wear Behavior ◽  
Surface Hardness ◽  
Erosive Wear ◽  
Gray Iron ◽  
Case Depth ◽  
Cast Irons ◽  
Beneficial Effects ◽  
Erosion Mechanisms

A 1.2-kW, continuous wave, CO2-gas laser was used to transformation harden or melt the surface of gray and ductile cast irons. Effects of surface-hardened layers on solid particle erosion showed that the erosion rate decreased with an increase in surface hardness and case depth. The order of matrix microstructures that increased the erosion rate were ledeburite, tempered martensite, and pearlite. These results were opposite to those observed in bulk-hardened alloys. Erosion mechanisms of brittle, gray iron included micromachining in the untreated condition and grain boundary cracking in the laser-treated condition. In contrast, erosion modes of ductile iron were plastic flow followed by cracking in the untreated condition and platelet formation and fatigue in the laser-treated conditions. The beneficial effects of surface hardening on erosion were examined and discussed.

Laser Heat Treatment of Cast Irons—Optimization of Process Variables: Part I

1985 ◽  
Vol 107 (3) ◽  
pp. 200-207 ◽  
Author(s):  
A. K. Mathur ◽  
P. A. Molian
Keyword(s):  
Heat Treatment ◽  
Gray Iron ◽  
Case Depth ◽  
Laser Heat Treatment ◽  
Process Variables ◽  
Cast Irons ◽  
Maximum Coverage ◽  
Laser Heat ◽  
Ring Mode ◽  
Better Than

A 1.2 kw CO2-CW laser operating in ring and Gaussian beam modes was used to surface harden gray and ductile cast irons. The microstructure, case depth, hardness, surface integrity, and distortion were studied as functions of process variables (i.e., laser power, focusing optics, beam size, scan rate and thickness of the specimen). The results indicate that the ring mode is preferred over Gaussian whereas ductile iron response to laser heat treatment is better than gray iron. The maximum case depth achieved with minimum melting was 0.38 mm, and the maximum coverage rate obtained was 322.58 mm2/s.

Optimization of the Case Depth of a Cylinder Made With 4340 Steel by a Control of the Laser Heat Treatment Parameters

2018 ◽  
Author(s):  
Rachid Fakir ◽  
Noureddine Barka ◽  
Jean Brousseau
Keyword(s):  
Heat Treatment ◽  
Numerical Model ◽  
Surface Temperature ◽  
Laser Power ◽  
Case Depth ◽  
Maximum Temperature ◽  
Laser Heat Treatment ◽  
Laser Heat ◽  
4340 Steel ◽  
Cylindrical Workpiece

This paper presents a numerical model able to control the temperature distribution along a 4340 steel cylinder heat-treated with Nd: YAG laser. The numerical model developed using the numerical finite element method, was based on a study of surface temperature variation and the adjustment of this temperature by a control of the heat treatment laser power. The proposed analytical approach was built gradually by (i) the development of a numerical model of laser heat treatment of the cylindrical workpiece, (ii) an analysis of the results of simulations and experimental tests, (iii) development of a laser power adjustment approach, and (iv) proposal of a laser power control predictor using neural networks. This approach was made possible by highlighting the influence of the fixed (non-variable) parameters of the laser heat treatment on the case depth, and has shown that it is possible by controlling the laser parameters to homogenize the distribution of the maximum temperature reached on the surface for a uniform case depth. The feasibility and effectiveness of the proposed approach leads to a reliable and accurate model able to guarantee a uniform surface temperature and a regular case depth for a cylindrical workpiece of a length of 50-mm and with a diameter of between 16-mm and 22-mm.

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.

scholarly journals Characteristics of Laser Heat Treated Ductile Cast Irons.

1992 ◽  
Vol 58 (548) ◽  
pp. 661-667
Author(s):  
Hidenobu MATSUYAMA ◽  
Kimihiro SHIBATA
Keyword(s):  
Cast Irons ◽  
Laser Heat ◽  
Heat Treated

Influence of Alloying on the Uniformity of Strength and Structure of Gray Iron

2012 ◽  
Vol 490-495 ◽  
pp. 3348-3352
Author(s):  
Li Li Xiao ◽  
Feng Zhang Ren ◽  
Meng Qi Liu ◽  
Yu Fei Wang ◽  
Na Wen Zhang ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Cast Iron ◽  
Cutting Force ◽  
Gray Cast Iron ◽  
Brinell Hardness ◽  
Pure Copper ◽  
Gray Iron ◽  
Gray Cast ◽  
Micro Hardness ◽  
Cast Irons

Two gray cast irons with equal tensile strength were prepared to investigate the influence of alloying on the machinability of gray iron. After 75SiFe modifying treatment, they were alloyed by the mixture additive containing RE, Cr, Mn, Si and Fe with a certain proportion and pure copper, respectively. The hardness, section sensitivity, structuralhomogenity and machinability were tested in this experiment. The results show that both of the gray irons have the same brinell hardness and the micro-hardness. The section sensitivity of the gray iron alloyed by the mixture additive is smaller than the gray iron alloyed by copper. The main cutting force of the cast iron alloyed by the mixture additive is lower than that of the cast iron alloyed by copper, therefore, the gray cast iron alloyed by the mixture additive has a better machinability than the cast iron alloyed by copper.

The Effect of Semi-Solid Parameters on the Microstructure and Hardness of High Chromium Cast Irons

2010 ◽  
Vol 457 ◽  
pp. 84-89 ◽  
Author(s):  
Arash Inanlou ◽  
S. Hossein Seyedein ◽  
M. Reza Aboutalebi
Keyword(s):  
Heat Treatment ◽  
Casting Process ◽  
Cast Irons ◽  
Inclined Plate ◽  
Cooling Plate ◽  
High Chromium ◽  
Primary Austenite ◽  
Heat Treated ◽  
Before And After ◽  
Semi Solid

High chromium cast iron samples of 14% Cr and 24% Cr were produced in sand and permanent mold using semi-solid casting process. A series of experiments were carried out to clarify the effect of copper cooling plate and mold cooling rate on microstructure, particularly morphology and sphericity of primary austenite, hardness and heat treatment cycles. Results show that for 14% Cr and 24% cast irons casting at 10 and 15 degrees of inclined plate result in better sphericity and distribution of primary austenite and carbides. Moreover hardness comparison of both semi-solid iron alloys using copper cooling plate at of this special morphologies resulted from cooling plate investigated by making them heat treat at 1050 centigrade °C for 1 and 2 hours. Hardness results show both heat treated 14 and 24% Cr alloy in 1 hours have hardness comparable with those alloys traditionally cast optimum angles with respect to conventional casting show higher hardness in every condition. Effect but heat treated in 2 hours. Finally X-Ray diffraction pattern taken from specimens before and after heat treatment confirmed with observed phases in optical microscopy before and after heat treatment.

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