Yada Polsen, Panyawat Wangyao, Nutthita Chuankrerkkul, Patama Visuttipitukul, Ruangdaj Tongsri, Gobboon Lothongkum
April 29, 2021
Specimens of P/M 316 L stainless steel and modified P/M 316 L stainless steel with various amounts of Cr, Ni, and Cr along with Ni additions were compressed by a 500 MPa-hydraulic press for a duration of 30 s and then sintered at 1573 K in a hydrogen atmosphere for 2.7 ks. The oxidation resistance tests of those specimens were carried out at 1173 K in air for 360 ks. The 5 wt.-% Cr-added specimen resulted in the best oxidation resistance with the lowest oxidation rate constant of 1.54 × 10 -7 kg 2 × m -4 × s -1 . The oxidation products which formed inside the pores and on the surfaces of all specimens were analyzed using scanning electron microscope/energy dispersive spectroscopic (SEM/EDS) and X-ray diffraction (XRD) analysis techniques. The results show that the oxides forming on both inside pores and surfaces were identified as Cr 2 O 3 , Fe 2 O 3 , (Fe 0.6 Cr 0.4 ) 2 O 3 , NiFe 2 O 4 and NiCr 2 O 4 in all tested conditions. The measured hardness of the modified specimens was in the range of 87-92 HRB, compared to the hardness of the 316 L specimen, which was 93 HRB. Increasing the amount of powder added provided a slightly lower hardness value due to increased porosity.