Gas well steel weld brittle fracture

Tom's notched-vs-smooth 1045 tensile bar experiment to demonstrate that triaxiality alone — not material brittleness — can switch fracture mode from ductile dimples to cleavage. Used to refute the opposing experts' claim that brittle-looking fracture proved brittle material.

What difference does that make? I had a debate with some people a year and a half ago — we had some brittle-looking fractures in some steel welds that were down in a hole in the ground in a gas well. The people said, oh, this proves that this is a brittle material that people put in the ground originally. So we went and bought some 1045 steel. 1045 steel is plain carbon steel, carbon-manganese steel. The actual bar we had was 46 rather than 45 carbon, but there's a range. It's just carbon, manganese, and some phosphorus and sulfur impurity — garden-variety steel.