Microstructural Analysis for Series 300 Stainless Steel Sheet Welds and Tensile Samples

摘要

The hot cracking susceptibility of some 300 series stainless steel welds can be minimized by the presence of a small amount of delta ferrite in the microstructure. The identification and location of the delta ferrite require a highly sensitive procedure. A similar challenge is involved in the resolution of strain-induced martensite. Hagnetic etching, which involves the use of an iron colloid solution in a controlled magnetic field, meets many of the demands for resolving these ferromagnetic features in the microstructure. The technique produces an analog pattern with the colloid that is observed in-situ with the conventionally etched microstructure and offers high resolution analysis of the ferromagnetic delta ferrite and martensite in the paramagnetic austenitic matrix. The technique, which can be applied to the upper limit of the magnification of an optical metallograph, is described. 14 figs. (ERA citation 09:026351)