The invention discloses a method for homogenizing a
microstructure of a low-temperature high
manganese steel
welding heat affected zone by using
pulse current, and belongs to the technical field of
welding and postweld heat treatment of high
manganese steel for
liquefied natural gas (LNG) storage and transportation. The treatment method comprises the following steps: (1) sampling a
heat affected zone of the low-temperature high-
manganese steel welded joint with
microstructure gradient distribution; (2) the low-temperature high manganese steel
welding heat affected zone sample is subjected to
pulse current treatment at the
room temperature, the
pulse frequency ranges from 0.6 kHz to 6 kHz, the pulse width ranges from 0.2 ms to 6 ms, the
current density ranges from 20 A / mm < 2 > to 200 A / mm < 2 >, and the
treatment time ranges from 5 min to 120 min; and (3)
grinding and
polishing the sample, observing and analyzing the element distribution state in the heat affected zone, and quantitatively representing the
grain boundary structure characteristics. According to the method,
atomic diffusion,
dislocation slippage and
grain boundary migration of the low-temperature high-manganese steel welding heat affected zone can be promoted by applying the
pulse current, redistribution of segregated atoms and dislocations in grains and at grain boundaries is rapidly achieved, and then the purposes of improving the
microstructure uniformity of the low-temperature high-manganese steel welding heat affected zone and improving the
impact toughness of the low-temperature high-manganese steel welding heat affected zone are achieved. The method is easy to operate, short in
treatment time,
environmentally friendly and particularly suitable for postweld treatment of low-temperature high manganese steel parts.