Surface Integrity of H13 ESR Mould Steel Milled by Carbide and CBN Tools

Abstract

The quality of a mechanical component such as its geometrical accuracy stability and fatigue life are significantly affected by the surface integrity generated by machining process. Residual stresses are a major part of the mechanical state of a machined layer and they can be beneficial or detrimental depending of their nature and magnitude. This study concerns phase analysis and residual stress profile characterization by X-ray diffraction (XRD) technique and microhardness profile of AISI H13 ESR mould steel, milled using carbide and CBN tools. Analysis of the cross-section of the AISI H13 ESR samples, milled using both tools, reveal a martensitic microstructure, with a very thin layer heavily deformed due to the machining process. However, no phase transformation was detected by XRD. Concerning the residual stresses, the results show that they are predominantly compressive at the samples surface. However, depending of the cutting tools, the in-depth residual stresses profiles present different evolutions. This difference in the in-depth residual stresses profiles between the two kind of cutting tools is attributed to the different cutting tool parameters, including the tool geometry.

A review of surface integrity in machining and its impact on functional performance and life of machined products

“…The status of SI at the end of tool-life is not obvious. 2002Detailed information about SI parameters in cavity milling of H13 is available in recently published work (Chandrasekaran et al, 2005;Marques et al, 2006). Here, the role of material microstructure (effect of inclusion content and special additives), cutting tools (coated carbide and PCBN) and cutting conditions including tool-wear on surface finish and sub-surface residual stress profile were systematically mapped in face milling (cutter diameter of 43 mm).…”

Surface integrity predictions and optimisation of machining conditions in the turning of AISI H13 tool steel

“…The PCBN cutting tool generates higher tensile residual stress values when compared to those generated by the coated cemented carbide cutting tool. The tendency of the PCBN cutting tool to increase the residual stresses was also reported by Marques et al (2006). When comparing with the coated cemented carbide cutting tools, the higher negative effective tool rake angle of the PCBN chamfered tools, combined with its lower thermal conductivity (44 W/mK for the PCBN and 100 W/mK for the coated cemented carbide) (Jawahir and Van Luttervelt, 1993), will conduct more thermal energy to the workpiece (Outeiro et al, 2006).…”

“…In this case, increasing all three cutting parameters renders the surface residual stresses less compressive. Marques et al (2006) analysed the residual stresses induced by the dry face milling of AISI H13 (50 HRc) tool steel with improved machinability, using both coated cemented carbide (with edge hone) and PCBN (with chamfer) cutting tools. They found predominantly compressive residual stresses at the machined surface and subsurface, these stresses being more compressive when using the coated cemented carbide cutting tool.…”

Surface Integrity Characterization and Prediction in Machining of Hardened and Difficult-to-Machine Alloys: A State-of-Art Research Review and Analysis

“…Increasing cutting speed and feed per tooth caused the compressive stresses to decrease due to a likely increase in thermal effect on the machined surface (Axinte and Dewes, 2002). The tool geometry changes the contact length between the tool and the workpiece as well as the cutting temperature and cutting forces; thus the different tool geometries results in different residual stresses profile (Marques et al, 2006). When compared with hard turning, the "hook" shaped residual stress profile does not occur in Figure 13.…”