Study on the Effect of Grinding Parameters to the White Layer Formation in Grinding SKD-11 Hardened Steel

2008 ◽  
Vol 53-54 ◽  
pp. 279-284 ◽  
Author(s):  
Wei Wei Ming ◽  
Qing Long An ◽  
Ming Chen
Keyword(s):  
Rapid Heating ◽  
White Layer ◽  
Ground Surface ◽  
Hardened Steel ◽  
Manufacturing Processes ◽  
Layer Formation ◽  
Machined Surface ◽  
Variable Parameters ◽  
Die Steel ◽  
White Layer Formation

White layer formed in the machined surface has been observed in many manufacturing processes. However, grinding has been considered more sensitive to form white layer due to the characteristics with high temperature and rapid heating and quenching. As an effective process to the difficult-to-machining die steel, grinding is widely used in the finishing of die and mould components with high precision. So study on white layer formed in ground surface is significant to improve the product quality and life. In this paper, grinding experiments focus on SKD-11 hardened steel with variable parameters were conducted to study the white layer formation and the parameter optimization to develop the favorable white layer and restrict the thickness of the dark-etching layer and the hot-affective region.

The Effect of Cryogenic Cooling on White Layer Formation in Hard Machining

2011 ◽  
Author(s):  
D. Umbrello ◽  
S. Caruso ◽  
S. Yang ◽  
F. Crea ◽  
O. W. Dillon ◽  
...  
Keyword(s):  
Rapid Heating ◽  
White Layer ◽  
Phase Changes ◽  
Cryogenic Cooling ◽  
Composition Analysis ◽  
Layer Formation ◽  
Machined Surface ◽  
Cooling Conditions ◽  
Electron Microscopes ◽  
White Layer Formation

Microstructural phase transformations, commonly named as the white layer on hard turned components, have in recent times become an interesting research topic in machining. Three main theories have been proposed to justify the mechanisms of white layer formation: (i) rapid heating and quenching; (ii) severe plastic deformation; (iii) surface reaction with the environment. Furthermore, coolant application also affects the surface microstructural alterations resulting from machining operations, which have a significant influence on product performance and life. The present work aims at understanding the effects of cryogenic coolant application on machined surface alterations during orthogonal machining of hardened AISI 52100 bearing steel. Experiments were performed under dry and cryogenic cooling conditions using cubic boron nitride (CBN) tool inserts with varying initial hardness and tool shape. Several experimental techniques were used in order to analyze the machined surface. In particular, optical and scanning electron microscopes (SEM) were used for characterizing the surface topography, whereas the microstructural phase composition analysis and chemical characterization have been performed using X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) techniques. The experimental results prove that the microstructural phase changes are partially reduced or can be totally avoided under certain cryogenic cooling conditions. Therefore, cryogenic cooling has the potential to be used for achieving enhanced surface integrity, thus contributing to improved product life and functional performance.

Influence of Cutting Speed on Surface Plastic Deformation and White Layer Formation of FGH95

2013 ◽  
Vol 589-590 ◽  
pp. 70-75 ◽  
Author(s):  
Jin Du ◽  
Zhan Qiang Liu
Keyword(s):  
Plastic Deformation ◽  
Surface Integrity ◽  
White Layer ◽  
High Reliability ◽  
Cutting Speed ◽  
Surface Plastic Deformation ◽  
Surface Plastic ◽  
Layer Formation ◽  
Machined Surface ◽  
White Layer Formation

The superalloy parts in the aeronautical field demand high reliability, which is largely related to surface integrity. Surface integrity generally includes three parameters, such as geometric parameter, mechanical parameter and metallurgical parameter. The paper presents the influence of cutting speed on surface plastic deformation and white layer formation through orthogonal milling of FGH95 superally material. The influence of cutting speed on grain refinement of machined surface is also investigated. It is found that cutting speed has significantly effect on the surface metallurgical characteristic microstructure. The increasing of cutting speed creates severer plastic deformation. Surface plastic shear strain increases with the increasing of cutting speed, while the depth of plastic deformation decreases on contrary. White layer thickness is increased with the increasing of cutting speed. Through statistical analysis for grains number, it can be drawn that the higher the cutting speed, the more serious grains refinement.

scholarly journals White layer formation mechanism in dry turning hardened steel

2018 ◽  
Vol 12 (2) ◽  
pp. JAMDSM0044-JAMDSM0044 ◽  
Author(s):  
Chunzheng DUAN ◽  
Fangyuan ZHANG ◽  
Wei SUN ◽  
Xinxin XU ◽  
Minjie WANG
Keyword(s):  
Formation Mechanism ◽  
White Layer ◽  
Hardened Steel ◽  
Layer Formation ◽  
Dry Turning ◽  
White Layer Formation

The Effect of Technological Conditions of Hard Turning on the Formation of White Layer

2016 ◽  
Vol 862 ◽  
pp. 96-103 ◽  
Author(s):  
Zoltán Pálmai ◽  
János Kundrák
Keyword(s):  
Hard Turning ◽  
White Layer ◽  
Layer Formation ◽  
Technological Parameters ◽  
Machined Surface ◽  
Border Line ◽  
Measurement Results ◽  
Composition Structure ◽  
Gear Wheels ◽  
White Layer Formation

In fast spreading hard turning occasionally a so-called white layer appears on the machined surface, which is mostly harmful. The formation of white layers and their composition, structure and thickness were investigated in the turning of the inner cylindrical surface of gear wheels made from 20MnCr5 case hardened steel, in order to identify to what extent the technological parameters of turning influence the white layer formation. On the basis of the measurement results it was possible to include border-line technological conditions in an empirical formula with which white layer formation can be avoided.

Investigation on White Layer Formation in PCBN Hard Turning GCr15

2010 ◽  
Vol 431-432 ◽  
pp. 241-244 ◽  
Author(s):  
Bao Yun Qi ◽  
Ning He ◽  
Liang Li ◽  
Wei Zhao
Keyword(s):  
Phase Transformation ◽  
Hard Turning ◽  
Rapid Heating ◽  
White Layer ◽  
Hard Machining ◽  
Layer Formation ◽  
Thermally Induced ◽  
Pcbn Tools ◽  
White Layer Formation ◽  
Machined Surfaces

It is commonly believed that the white layer formed during hard machining of steels is caused primarily by a thermally induced phase transformation resulting from rapid heating and quenching. The focus of this study is to investigate the white layers produced on the machined surfaces and on the inner side part of the chips in dry hard turning GCr15 with PCBN tools. Samples of machined workpiece and chips were metallographically processed and observed under a microscope to determine whether white layers were present or not. Some properties of white layers were deduced in order to verify some of the prevalent theories. More specifically, chip shapes were studied to determine how they developed during machining with potential appearance of white layers, with a view to correlating the chip shapes with the white layer formation.

Effects of Sequential Cuts on White Layer Formation and Retained Austenite Content in Hard Turning of AISI52100 Steel

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Xiao-Ming Zhang ◽  
Xin-Da Huang ◽  
Li Chen ◽  
Jürgen Leopold ◽  
Han Ding
Keyword(s):  
Layer Thickness ◽  
Process Parameters ◽  
Retained Austenite ◽  
Hard Turning ◽  
White Layer ◽  
Layer Formation ◽  
White Layer Thickness ◽  
Austenite Content ◽  
Sequential Cuts ◽  
White Layer Formation

This technical brief is the extension of our previous work developed by Zhang et al. (2016, “Effects of Process Parameters on White Layer Formation and Morphology in Hard Turning of AISI52100 Steel,” ASME J. Manuf. Sci. Eng., 138(7), p. 074502). We investigated the effects of sequential cuts on microstructure alteration in hard turning of AISI52100 steel. Samples undergone five sequential cuts are prepared with different radial feed rates and cutting speeds. Optical microscope and X-ray diffraction (XRD) are employed to analyze the microstructures of white layer and bulk materials after sequential cutting processes. Through the studies we first find out the increasing of white layer thickness in the sequential cuts. This trend in sequential cuts does work for different process parameters, belonging to the usually used ones in hard turning of AISI52100 steel. In addition, we find that the white layer thickness increases with the increasing of cutting speed, as recorded in the literature. To reveal the mechanism of white layer formation, XRD measurements of white layers generated in the sequential cuts are made. As a result retained austenite in white layers is identified, which states that the thermally driven phase transformations dominate the white layer formation, rather than the severe plastic deformation in cuts. Furthermore, retained austenite contents in sequential cuts with different process parameters are discussed. While using a smaller radial feed rate, the greater retained austenite content found in experiments is attributed to the generated compressive surface residual stresses, which possibly restricts the martensitic transformation.

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