Effect of Rare Earth Elements on Machining Characteristics of Austenitic Stainless Steels without Lead Addition

Rare earth elements (REE) are harmless for human health. REE addition contributes to the improvement of the machinability of the steels. In the present paper, machining characteristics of austenitic stainless steels without lead addition were investigated by adding free-machining elements, such as sulfur, REE and bismuth. The results have shown that large numbers of rounded, globular shaped inclusions were obtained for both steels. The machinability of steel B is better than that of steel A, and the cutting forces of steel B are lower than those of steel A at various cutting speeds. Lead can be substituted by REE and bismuth in free machinable austenitic stainless steels. REE significantly affects machining characteristics of austenitic stainless steels without lead addition. The mechanical properties of both steels were similar, and their fracture exhibited ductile characteristics. Satisfactory machinability and mechanical properties can be obtained for both steels.

Low Environmental Impact Machining Processes of Free Cutting Austenitic Stainless Steels without Lead Addition

Environmental protection is a growing concern for many industries today. This paper shows manufacturing environmental performance improvement for free cutting steel products. Inclusions have the characteristics of sulfur and bismuth in free cutting austenitic stainless steels without lead addition. Machinable additives lead to improved chip breakage, and thus reduced tool wear. The machinability of free cutting austenitic stainless steels without lead addition is much better than that of conventional austenitic stainless steel. Bismuth can replace lead because lead is a harmful factor for environment and machine operators' health. The reduction of environmentally harmful substances such as lead was performed. A feasible combination of free-cutting additives should yield a stainless steel product with acceptable machining and mechanical properties.