Product Code: ICAL05_1602

Improvement of IGC Resistance of SUS 304 Stainless Steel by Laser Surface Melting Based on Grain Boundary Engineering
Authors:
Sen Yang, Inner Mongolia University of Technology; Hohhot Peoples Republic of China
Presented at ICALEO 2005

In order to improve the intergranular corrosion resistance of 304 stainless steels, laser surface melting was conducted on commercial 304 stainless steel, and the microstructure evolution and GBCD (grain boundary character distribution) were investigated. Experimental results showed that the fraction of low S CSL grain boundaries (1S29) increased with increase of heat-treatment time when the laser-remelted specimens were heat-treated at 947C. Under laser surface remelting condition, the optimal processing parameters were 947C and 28hs, and the fraction of low S CSL grain boundaries reached 88.4%. Accompanying the formation of high frequency low S boundaries, the continuous random grain boundary network was extremely dispersed by introduction of low energy segments on migration random boundaries during twin emission and boundary-boundary reactions in the grain growth. EPR experiments showed that the ratios of the reactive current of GBE (grain boundary engineering) materials were much smaller than that of the BM (base materials) under the same sensitization condition, which meant that susceptibility to intergranular attack of BM was remarkably improved. For BM, a complete grain boundary attack in a continuous network existed whereas for GBE specimens a slight grain boundary attacks was observed after EPR test.