The Effect of Heat Gas Nitriding on Some Mechanical Properties of Plain Carbon Steel B St-3 sp

This paper describes the effect of heat NH3-gas treatment of samples of plain carbon steel (B St-3 sp) to improve some mechanical properties (hardness, corrosion rate). The samples represent machine parts and tools. The purpose of sample treatment is to get more wear, fatigue and corrosion resistance under abnormal working conditions (pressure, temperature, etc.), keeping the core of samples flexible to absorb the exerted shocks. The study aims to determine the micro-hardness using Vickers tester, and it ranges between 150-400 kg/mm2. To verify this data the micro-structure of surface layers was studied by using optical microscope and scanning electron microscope (JMS- 6490LV). To examine corrosion resistance, the samples were monthly plunged in seawater for a period of year. The ratio (Δm/m)% was measured by weighted method.