Machinability Improvement and Its Mechanism in SUS304 Austenitic Stainless Steel by h-BN Addition

Abstract

In order to improve the machinability of Type 304 austenitic stainless steels, 0.016 mass % boron and 0.2 mass % nitrogen were added, and hexagonal boron nitride (h-BN) particles (1~5 μm diameter) were precipitated. During turning with cemented carbide insert, cutting force and tool wear were reduced by h-BN precipitation, especially at higher cutting speed of more than 40 m/min. The reduction of cutting force seems to be due to the internal lubrication effect of h-BN in chip shear region and deformation flow layer, along with the lubrication between chip and carbide tool. Better disposability of chip and suppression of tool wear were also achieved by h-BN precipitation. Good machinability of h-BN precipitated Type 304 steel was also found in drilling and sawing with high-speed steel tools.

Influence of Boron and Nitrogen on the Machinability, Polishability and Wear of Martensitic Stainless Steels

“…During solidification, sulfur combines with manganese to form manganese sulfide (MnS) non-metallic inclusions. Manganese sulfides play a vital role in improving machinability [4,8,9]. When machining, MnS acts as a lubricant, reducing friction and extending tool life while yielding a superior surface finish.…”

“…The use of boron nitride (BN) also demonstrated enhanced machinability in austenitic stainless steels [9] and heat-treatable steels [10,11]. Chen et al showed the potential benefits of using both manganese sulfides (MnS) and boron nitride (BN) simultaneously to improve machinability [12].…”

Effect of Machining Parameters on Tool Wear and Surface Roughness In Dry and Wet Machining of Aisi 316 Austenitic Stainless Steel by Taguchi Method

“…Stainless steels are widely used to manufacture mechanical components because of its outstanding mechanical properties, corrosion resistance and good weldability [1]. It contains chromium which prevents corrosion of the steel.…”