Stainless Steel Technical Guide

Stainless steels are capable of meeting a wide range of final needs – corrosion resistance, strength at elevated temperatures, toughness at cryogenic temperatures etc., and are selected for a broad range of applications. Designers need to be familiar with properties of the various types available and should consider the advice of corrosion and welding consultants when specifying stainless steel grades for commercial service.

The three major classes of stainless steels that have been widely used in industrial applications for over 50 years are designated martensitic (e.g. AISI 410), ferritic (e.g. AISI 430) and austenitic (e.g. AISI 304) – names derived from the predominant crystal structure or phase normally found at room temperature. A fourth class, the PH or precipitation hardening types (e.g. 17/4 PH), has also come into prominence within the last 25 years. More recently there is great interest in the Duplex or ferritic-austenitic class (e.g. 2205 alloy). Hobart suggested for welding the above stainless steels are listed in Figure 66 on page 55 and Figure 67 on page 56. Since the austenitic class is the major stainless steel class specified for welded structures, more attention will be devoted to this esteemed and hallowed group of chromium-nickel alloys than to the other classes of stainless steel.