Selecting Filler Metals for Stainless Steel Here are answers to your questions on how to choose the right filler metal for your stainless steel application The capabilities that make stainless steel so attractive — the ability to tailor its mechanical properties and resistance to corrosion and oxidation — also increase the complexity of selecting an appropriate filler metal. For any given base material combination, any one of several types of electrodes may be appropriate depending on cost issues, service conditions, desired mechanical properties, and a host of welding-related issues. This article provides the necessary technical background to give the reader an appreciation for the complexity of the topic and then answers some of the most common questions filler metal suppliers receive. It establishes general guidelines for selecting appropriate stainless steel filler metals — and then explains all the exceptions to those guidelines. The article does not cover welding procedures, as that is a topic for another article. Four Grades, Many Alloying Elements There are four principal categories of stainless steels: austenitic, martensitic, ferritic, and duplex (Table 1). The names are derived from the crystalline structure of the steel as it is normally found at room temperature. When low-carbon steel is heated above 1550°F, its atoms are rearranged from the structure called ferrite at room temperatures to the crystal structure called austenite. On cooling, the lowcarbon steel atoms return to their original structure, ferrite. The hightemperature structure, austenite, is nonmagnetic and has lower strength 32 WELDING JOURNAL / JULY 2016 BY JAY COUBROUGH AND KARIN IVARSSON Fig. 1 — To reduce the risk of intergranular corrosion issues, consider using a Type L filler material.
Welding Journal | July 2016
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