Effect on wear resistance of a laser-induced hardening system for cylinder liners

Andriyakhin, V. M.; Васильев, В. А.; Sedunov, V. K.; Chekanova, N. T.

doi:10.1007/bf00769325

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“…Nesse ponto, o feixe se comprime em uma pequena extensão circular de raio wo chamada de cintura do feixe e unicamente determinada pela geometria dos espelhos. A cintura do feixe possui um raio dado por: Wo={Á.L/27ry''~ (6) O volume excitado situado fora do eixo óptico quase não é utilizado, o que explica a insignificante taxa de preenchimento desse tipo de ressonador.…”

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“…Os efeitos que ocorrem na superfície do material tratado decorrem de um desses três processos, constituindo a base para o desenvolvimento de numerosos métodos de tratamento térmico de materiais a laser que, por exemplo, aumentam o desempenho de componentes de máquinas e ferramentas de corte [Altshulin, 1990] [ Andriyakhin, 1983] O primeiro grupo incorpora métodos de tratamento a laser que não causam fusão ou qualquer outra mudança na rugosidade inicial da superfície, e são associadas somente com o aquecimento da camada superficial do material tratado e seu subsequente autoresfriamento. Pelo controle do processo de aquecimento e resfriamento é possivel obter diferentes efeitos na camada superficial, em particular, têmpera, revenimento e recozimento.…”

Section: -Tratamento Térmico Superficial Via Laserunclassified

“…Dentro dessas condições o material na camada superficial é autotemperado. O efeito de endurecimento, observado primeiramente em aços carbono e em alguns aços especiais, consiste de uma formação especifica, altamente dispersa, de pequena penetração da estrutura espacialmente distorcida na camada superficial [Andriyakhin, 1980] [Blaes, 1988 [Gurkovsky, v. 10,1990]. Essa estrutura contém blocos com alta dispersão e alta densidade de discordâncias, e sua microdureza é de 1,5 a 5 vezes maior que a estrutura do material recozido.…”

Section: -Tratamento Térmico Superficial Via Laserunclassified

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Investigação do processo de endurecimento de materiais via laser

Berretta¹

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In this work, the laser hardening process has been investigated using the AISI 1045 steel. The effects of the variables diameter (^f), energy density (Wg) and power density (Wp) of the laser beam, as well as, the environmental atmosphere (room and argon) during irradiation, on the surface hardening, was analyzed for single point and multiple point (trail of points) irradiations. Vickers indentation micro hardness, optical metallography, scanning electron microscopy and X-ray diffraction were utilized for the characterization of the laser beam affected zone. For the single point irradiation it was verified that: the laser affected zone has a spherical cap (shell) shape with dimensions strongly sensitive to laser beam parameters and enviroiunental atmosphere; the hardness measured on surface, as well as along the depth (transversal section of the affected zone), is maximum near the surface and decreases rapidly in the interface between the affected zone and the base metal; the action of laser beam induces a strong increase in the AISI 1045 hardness; from an initial value of 250 HV to maximum values in the range 800-1000 HV; the microestructure of the affected zone is composed of two regions, one, near the surface of irradiated material, characterized by the presence of highly refined martensite, and, another, a transition region, where martensite coexists with proeutectoide ferrite. The investigation performed on multiple point irradiation (trail of points) has given initial information for a better definition of the surface hardening of parts; concerning the laser parameters and the geometry of the pulse distribution on the part surface. Also, a phenomenological equation relating the maximum depth of the laser affected zone, z, with beam parameters was obtained, given by: ^""^ ^~^/A/^V^) where the parameter A depends on the environment atmosphere, and B is only slightly dependent on Wp. With the use of this equation a monogram was constructed, which can be usea for routine surface hardening operations with AISI 1045 carbon steel. This monogram, if enriched with data from others materials, may be eventually used by the laser designer to choose the better range for the laser beam parameters adequate to surface hardening, owing to dedicated, more economical laser equipments.

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Section: -Tratamento Térmico Superficial Via Laserunclassified

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Investigação do processo de endurecimento de materiais via laser

Berretta¹

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Surface Engineering With Lasers

Steen

1987

Applied Laser Tooling

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Effect of laser treatment on the wear resistance of steels

Safonov¹,

Aleksenko²

1998

Met Sci Heat Treat

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It is known that laser hardening increases the wear resistance of friction parts quite substantially. At the same time, many problems connected with the effect of the treatment process and the special features of laser hardening on the characteristics of wear resistance require detailed consideration. The present paper is devoted to the development of recommendations on choosing the optimum location and proportion of the areas of the hardened and unhardened regions of the surface of structural steels after their treatment with radiation of a continuous CO2 laser.Cylindrical specimens of steel 40KhlOS2M and fiat specimens of steels 45, 40Kh, and 38KhMYuA were treated with radiation of a continuous CO 2 laser with fusing the surface. The radiation power P, the rate of treatment v, and the diameter of the spot d s are presented in Table 1 (the regimes of laser treatment for steels 45 and 38KhMYuA are similar to that for steel 40Kh). The choice of laser treatment with fusing of the surface is connected with the fact that in this case the wear resistance of structural steels under conditions of boundary friction is increased considerably [1,2]. Specimens of steels 40KhlOS2M and 38KhMYuA were heat treated before the laser action, and specimens of steels 45 and 40Kh were normalized.In the course of the laser treatment a series of hardened strips 2 mm wide located a certain distance apart and inclined at an angle of 45 ~ to the generatrix of the cylinder were formed on the cylindrical surface of steel 40KhlOS2M. The area of the hardened strips amounted to 33, 50, and 75% of the total area of the specimens, which corresponded to a filling factor Kf equal to 0.33, 0.5, and 0.75, respectively. Some of the specimens were subjected to laser hardening over the entire cylindrical surface by creating annular strips overlapping 30% (Kf = 1.0). Hardened strips 2 mm wide were deposited on the surface of fiat specimens of steels 45, 40Kh, and 38KhMYuA at an angle of 45 ~ to the direction of motion in the wear resistance tests by analogy with the pattern of [3].After the laser treatment the functional surface of the specimens was polished to R a = 0.28 -0.34 pm. The microhardness of the polished surfaces of the hardened and unhardened regions was measured by means ofa PMT-3 device (at least 50 measurements on each region). The average microhardness H of the surface of the steel after the laser treamaent and its standard deviation S are presented in Table 1. 399Comparative tests for wear resistance were conducted under conditions of boundary friction by the standard methods (GOST 23224-86). Tests of round specimens were conducted on an SMTs-2 friction machine by the "disk-block" method with feeding of AS-8 oil into the friction zone at a rate of 20 -25 drops per minute. The immobile block of steel R6M5 had a hardness of 60 -62 HRC. The specific load in the tests was q = 2.5 and 5 MPa, the sliding rate was 1.05 m/sec, and the test base was N = 1.2 x 105 and 3.6 x 105 cycles, respectively. The specknens were preliminarily run in for 3 -...

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Effect on wear resistance of a laser-induced hardening system for cylinder liners

Cited by 3 publications

References 0 publications

Investigação do processo de endurecimento de materiais via laser

Investigação do processo de endurecimento de materiais via laser

Surface Engineering With Lasers

Effect of laser treatment on the wear resistance of steels

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