Grinding performance of hardened steel: a study about the application of different cutting fluids with corrosion inhibitor

The use of cutting fluid in the grinding process is crucial to guarantee quality in the products. However, most cutting fluids can cause disease to operators and damage the environment, which adds costs to the industry, as well as a deficit in the operator’s quality of life. In addition, the metalworking industry has as problem control corrosion in their parts; it demands to add the process of remove cutting fluid of the workpieces and add a protective oil on their surface. In this context, a new class of corrosion inhibitors that use water as a propagation medium, generically known as V-active® VCI, was formulated, which made it possible to develop, firstly, a cutting fluid with the addition of such inhibitor, called generically VCI 1, which would eliminate the process of degreasing and adding protective oil. Previous research has indicated the VCI 1 has an excellent performance in the grinding process, which promoted the development of two other new fluids (named generically VCI 2 and VCI EP) at a reduced market cost to make the product more competitive. In addition to the cost savings compared with the VCI 1, the VCI EP has the differential of an extreme pressure additive. It is noteworthy that the fluids in question pose no risk to humans and are biodegradable. Thus, the performance of these two new fluids with a corrosion inhibitor was verified in the grinding process of AISI 4340 steel with an aluminum oxide grinding wheel and the results were compared with the higher market cost V-active® VCI fluid and with a base fluid without the corrosion inhibitor. The comparison took place at three different feed rates (0.25, 0.50, and 0.75 mm/min). For each feed rate, the following were evaluated: surface roughness; roundness error, diametral grinding wheel wear, microhardness, optical microscopy, and acoustic emission, and the ground surface was analyzed using scanning electron microscopy (SEM). Therefore, useful information was obtained for the technological development of the rectification process, thus adding to scientific knowledge and dissemination of knowledge to society.