Dual pass, dual anneal welding method for joining high strength steels

A welding method comprising the steps of:

• providing a first surface of a first hardenable ferrous alloy having a first composition having a carbon equivalent (Ceq) of at least 0.45;
• providing a second surface of a second hardenable ferrous alloy having a second composition having a carbon equivalent (Ceq) of at least 0.45;
• creating an overlap by overlapping the first surface and the second surface;
• welding the first surface to the second surface by heating the first surface and the second surface at a sufficiently high enough temperature to raise temperatures of the first surface and the second surface to at least the melting points of the first and second alloys to form a weld;
• cooling the weld to between the Ac3 and Mf temperatures of the first and second alloys;
• heating the weld to heat the weld at a rate of at least 10 C./sec to a temperature between the Ms and Ac1 temperatures of the first and second alloys;
• cooling the weld to below the Ms temperatures of the alloys;
• heating the weld at a rate of at least 10 C./sec to a temperature between the Ms and Ac1 temperatures of the first and second alloys;
• cooling the weld to room temperature;
• wherein Ceq is defined as:
• Ceq=C+A(C)*[Si/24+Mn/6+Cu/15+Ni/20+(Cr+Mo+Nb+V)/5+5B];
• and
• A(C)=0.75+0.25 tanh [20(C-0.12)], the composition of each of the elements C, Si, Mn, Cu, Ni, Cr, Mo, Nb, V, and B being in wt. percent.