Calculating the Susceptibility of Carbon Steels to Solidification Cracking During Welding

Existing experimental results of weldability tests show the susceptibility of carbon steels to solidification cracking varies significantly with the C content. To analyze the effect of the C content on the susceptibility, equilibrium solidification of binary Fe-C alloys was assumed as an approximation in view of the rapid diffusion of the interstitial solute C in Fe. First, the curve of the equilibrium freezing temperature range vs. the C content was plotted and compared with the experimental results, but the agreement was not good. Then, the susceptibility index, i.e., |dT/d(f(S))(1/2)| near (f(S))(1/2) = 1 (T: temperature; f(S): fraction solid) recently proposed for Al alloys was tried. The curve of the susceptibility index vs. the C content was calculated. The curve agreed well with the experimental results of crack susceptibility tests of carbon steels in welding.

Automated summary

Experimental results have shown that the susceptibility of carbon steels to solidification cracking during welding is significantly influenced by the carbon content. However, the comparison between equilibrium freezing temperature range and carbon content did not yield satisfactory agreement with experimental results. By calculating the susceptibility index in relation to the carbon content, it was found that the curve aligned well with the actual crack susceptibility tests of carbon steels in welding.