Microstructure and Hardness of High Temperature Gas Nitrided AISI 420 Martensitic Stainless SteelNor Nurulhuda Md. Ibrahim, Patthi Hussain and Mohktar AwangMATEC Web of Conferences, 13 (2014) 04017DOI: https://doi.org/10.1051/matecconf/20141304017