Crack Formation during Hot Rolling of Nitrogen Alloyed Duplex Stainless Steels

Abstract

Duplex stainless steel with varying nitrogen contents of 0.22% (alloy 1) and 0.18% (alloy 2) were produced using a conventional induction furnace under normal ambient atmosphere. The samples were subsequently rolled under hot (1,000–1,100°C) conditions to various thickness reductions (15–75%). Both the hot rolled alloy samples were examined for the changes in microstructure and mechanical properties. The alloy 1 with higher nitrogen content opens out while deforming above 15%, whereas the alloy 2 deformation in the hot working zone is perfect without any defects. The crack initiation parameter for the alloy 1 is the secondary phase formation in the austenite area, which is brittle. The temperature range of 1,050 to 1,100°C is not desirable for hot rolling of alloy 1 and the same temperature range is suitable for hot rolling of alloy 2.

Keywords:

• Austenite
• Duplex stainless steel
• Microstructure
• Rolling
• Secondary phase