Turning of hardened AISI 4340 steel using coated carbide inserts

Abstract

The machining of hardened steels employing polycrystalline cubic boron nitride and ceramic tooling has been comprehensively investigated over the last 20 years; however, the development of newer cemented carbide grades has extended the use of this group of materials to the machining of steels hardened up to 45 HRC (Rockwell C). The current paper is therefore concerned with continuous turning of AISI 4340 steel hardened from 250 to 525 HV using coated carbide tools in order to investigate whether this cutting tool grade is capable of providing a satisfactory performance when machining a steel with increasing levels of hardness. Machining forces, tool life, and wear mechanisms were assessed and the results indicated that the relationship between the hardness of the work material and the machining force is not straightforward. In general, the machining force components increased with the work material hardness, however, the cutting force decreased slightly as the work hardness increased from 250 to 345 HV. Tool wear was lower when machining the 345 HV workpiece compared with cutting the 250 HV steel. Finally, abrasion was the principal wear mechanism observed and catastrophic failure took place when attempting to machine the 525 HV steel.

Predictive modeling for flank wear progression of coated carbide tool in turning hardened steel under practical machining conditions

“…However, harder workpiece employs higher cutting forces and generates higher cutting temperatures [1][2][3][4], which have a strong influence on the tool wear rate through different tool wear mechanisms like abrasion, adhesion, and diffusion. The tool wear, especially the flank wear, which adversely affects the dimensional accuracy and product quality, is the main hurdle in the wide implementation of coated carbide tools to machining of hardened steel in the industry.…”

Experimental investigations on machinability aspects in finish hard turning of AISI 4340 steel using uncoated and multilayer coated carbide inserts

“…de Lima et al [18] performed turning operation of AISI 4340 steel hardened from 250 to 525 HV using coated carbide tools to investigate its potentials of applications in hard turning. It is observed that, the machining force component increases with the work material hardness.…”

On the application of response surface methodology for predicting and optimizing surface roughness and cutting forces in hard turning by PVD coated insert

“…However, high performance of the TiAIN coated tool regarding wear resistance and surface finish. To investigate potentials of applications in hard turning, (Lima et al 2007) have carried out turning operations using coated carbide tools on AISI 4340 steel hardened from 250 to 525 HV. It was concluded that, the cutting force increases with the work material hardness.…”