Strong or brittle steel
 

Experience has shown that most cracks have occurred in higher yield steel. There is little anecdote available for LMAC in grade 43 steel. It is probable that softer steel can more easily yield to relieve excess stresses.

Likewise high carbon steels are more brittle and are perhaps more likely to crack. One problem is that much steel is too strong for its classification. Grade 43 steel often has yield stresses in the order of 325 N/m5, not 275. Sections are often 355 whether ordered or not. It is the actual yield stress, not the grade, that counts.

The internal structure of the steel is a very important factor, and may be measured by the carbon equivalent. The program has a table of expected Carbon Equivalents for typical BS grades of steel. Please be careful. Some low strength, low quality imported steel can prove to have very high carbon equivalents and can be very prone to cracking, regardless of the nominal grade.