Field girth welding technology for high manganese steel slurry pipelines
Welding compositions for high manganese steel base metals, the composition comprising: carbon in a range of about 0.4 wt % to about 0.8 wt %; manganese in a range of about 18 wt % to about 24 wt %; chromium in an amount of about 6 wt %; molybdenum in an amount of about <4 wt %; nickel in an amount of about <5 wt %; silicon in an amount of about 0.4 wt % to about 1.0 wt %; sulfur in an amount of about <200 ppm; phosphorus in an amount of about <200 ppm; and the balance comprising iron.
1. A weld metal for high manganese steel base metals, the weld metal being created by at least two high manganese steel base metals and a welding wire, the weld metal comprising:
carbon in a range of about 0.4 wt % to about 0.8 wt %;
manganese in a range of about 18 wt % to about 24 wt %;
chromium in an amount of about 6 wt %;
molybdenum in an amount of about <4 wt %;
nickel in an amount of about <5 wt %;
silicon in an amount of about 0.4 wt % to about 1.0 wt %;
sulfur in an amount of about <200 ppm;
phosphorus in an amount of about <200 ppm; and
the balance comprising iron;
wherein the weld metal has an austenitic microstructure; and
wherein the austenitic microstructure transforms into a hard α′-martensite and undergoes microtwinning upon straining.
2. The weld metal of claim 1 , further comprising at least one of:
titanium in an amount of about <2 wt %;
niobium in an amount of about <5 wt %;
tungsten in an amount of about <5 wt %;
aluminum in an amount of about 1.0 wt %;
boron in an amount of about <0.1 wt %;
nitrogen in an amount of about <1.5 wt % or a combination thereof.
3. A method of producing a weld metal of erosion/corrosion resistant high Mn steel,
the method comprising: providing at least two high Mn steel bases to be welded,
melting and cooling a welding filler material to create the weld metal, wherein the weld metal comprises carbon in a range of about 0.4 wt % to about 0.8 wt %, manganese in a range of about 18 wt % to about 24 wt %, chromium in an amount of about 6 wt %, molybdenum in an amount of about <4 wt %, nickel in an amount of about <5 wt %, silicon in a range of about 0.4 wt % to about 1.0 wt %, sulfur in an amount of about <200 ppm, phosphorus in an amount of about <200 ppm, and a balance comprising iron, wherein the weld metal has an austenitic microstructure, and wherein the austenitic microstructure transforms into a hard α′-martensite and undergoes microtwinning upon straining; and wherein an amount of carbon in the weld metal is less than an amount of carbon in a heat affected zone of the at least high Mn two steel bases.
4. The method of claim 3 , wherein melting comprising providing a welding heat input no more than about 2.5 kJ/mm to the welding filler metal.
5. The method of claim 3 , wherein the at least two high Mn steel bases comprise a portion to be welded, the portions having bevels of about 30 degrees to about 37.5 degrees.
6. The method of claim 3 , wherein the weld metal has a yield strength in the as-welded condition greater than a yield strength of a high manganese steel base.
7. The method of claim 3 , wherein the weld metal has a yield strength in the as-welded condition greater than about 70 ksi.
8. The method of claim 3 , wherein the weld metal has an ultimate tensile strength in the as-welded condition greater than about 82.7 ksi.
9. The method of claim 3 , wherein the weld metal has a tensile elongation in the as-welded condition greater than about 16%.
10. The method of claim 3 , wherein the weld metal has a solidification cracking temperature range in the as-welded condition of about 40° C. to about 170° C. at 7% strain.
11. The method of claim 3 , wherein the weld metal and/or a heat affected zone of the bases has a Charpy V-notch (CVN) energy at −29° C. in the as-welded condition greater than 27 J.
12. The method of claim 3 , wherein the at least high Mn two steel bases are an erosion/corrosion resistant high Mn steel.