Laser Quenching of TiN Coated Steel

Abstract

In a conventional process such as a ceramics thin nlm coating on steel after heat treatment in a furnace， the steel might be so softened by over heating ． TherefQre， we proposed a new method ： heat treatment after a TiN thin 五1m coating process ． HDwever ， thermal deformatiDD could be occurred in this process using a furnace． Therefore ， the present study focuses on the application of ！ aser quenching ． The method causes thermal strain less than that in the furnace quenching ， As experirnen − tal results ， it is revealed tha 亡YAG laser quenching of the TiN film coated steel without film damages is very di伍 cult because the film ox ｛ des and heat abs rption increases immediately during laser irradiation 、 Therefore， we propose some solutiQns ； First ， a Nu gas − assisting laser irradiation is performed to prevent from the oxidation of the TiN 且lm ． Second ， an absorbent is applied on the film in order to increase the thermal absorptiun ． As a result ， it is crarified that the proposed method is efFective to achieve laser quenching of TiN 丘1 【 n coated steels without the film damage ． Moreover ， it is shown that the 丘lm hardness and adhesive strength rnaintains enQugh ill this method ．

Strengthening of Ceramic Coated Steel by Laser Quenching

“…This shows that both power density (P/S d 2 ) and Energy per line (P/F) are important parameters to characterize the laser interaction with the materials. As reported in our previous paper [6], it was required to paint graphite absorbent on TiN surface in order to quench TiN coated steel efficiently because of the low heat absorption of TiN for YAG laser; the heat absorption measured by an UV-VIS-NIR spectrophotometer (UV-3101PC, Shimadzu, Japan) was 12%. However, for both types of specimens tested in this study, it was possible to quench the substrate effectively without absorbent.…”

“…Laser quenching is characterized by localized heat input and consequently very low thermal distortion when compared to furnace heat treatment. A fundamental study about laser quenching of TiN coated steel was carried out, and the proper conditions for laser quenching of TiN coated steel and the effects of laser quenching on the mechanical properties of TiN coated steel have already been reported [6]. In this study, to investigate the effectiveness of laser quenching for other ceramic coated steels, CrAlN and TiAlN coated steels were prepared, and laser quenching under various irradiation conditions were carried out.…”

Flaking Initiation Life under Rolling Contact Fatigue of Ceramic Coated Steels Quenched after Coating Process

“…It is possible to improve the substrate hardness 1 and the adhesive strength 1,2 of ceramic coated steels significantly by this method. Especially, by our latest method named "laser quenching after coating" 3,4 , applying laser quenching technique to the process of substrate quenching after coating, the adhesive strength and substrate hardness also can be improved without any detrimental effects on the hardness and the fracture strength of ceramic coating. Moreover, by applying laser quenching, high dimensional accuracy can be achieved, and "energy saving" and "environment-friendly" process can be expected.…”

Quenching of Ceramic Coated Steels by Scanning Laser

“…When the temperature during deposition is higher than the tempering temperature for a given type of substrate steel, the substrate hardness will typically decrease during the coating process. To solve this problem, "laser quenching after coating" was proposed [1,2]. It was found that laser quenching after coating allows for adequate steel hardness control regardless of the environment temperature during the process without high thermal distortion.…”

“…These results suggest that this method can be applied as an effective way to improve the performance of ceramic-coated steels. In our previous study [1,2], linear scanning laser heat treatment was carried out by using a Nd-YAG laser with a Gaussian type intensity distribution. Using this type sets limitations on the maximum width of the quenching region and may result in non-uniform hardness distribution in the laser irradiated region.…”