An apparatus for metallurgical heat-treatment includes a solid-oxide electrolyser, a furnace and a heat-exchanger. The electrolyser is arranged to electrolyse water and provide resulting hydrogen to the furnace. A first portion of the hydrogen from the electrolyser is combusted in a combustor to heat the furnace. A second portion provides a treatment atmosphere including hydrogen for the heat-treatment of a metal or metal alloy object. Water vapour output by the combustor is provided to the heat-exchanger which transfers heat within the water vapour to the solid-oxide electrolyser to improve or maintain its efficiency. In contrast to apparatus of the prior art, the apparatus does not produce carbon dioxide at the point of use. By applying waste heat, carried by the water vapour output from the combustor, to the electrolyser, the power consumption of the electrolyser is reduced for a given rate of electrolysis.

Provided are a steel sheet dehydrogenation apparatus, a steel sheet production system, and a steel sheet production method capable of producing a steel sheet excellent in hydrogen embrittlement resistance without changing the mechanical properties of the steel sheet. A dehydrogenation apparatus comprises: a housing configured to house a steel sheet coil obtained by coiling a steel strip; and a vibration application device configured to apply vibration to the steel sheet coil housed in the housing so that the steel sheet coil is caused to vibrate at a frequency of 100 Hz to 100,000 Hz and a maximum amplitude of 10 nm to 500 m.

Provided are a steel sheet dehydrogenation apparatus, a steel sheet production system, and a steel sheet production method capable of producing a steel sheet excellent in hydrogen embrittlement resistance without changing the mechanical properties of the steel sheet. A dehydrogenation apparatus comprises: a housing configured to house a steel sheet coil obtained by coiling a steel strip; and a vibration application device configured to apply vibration to the steel sheet coil housed in the housing so that the steel sheet coil is caused to vibrate at a frequency of 100 Hz to 100,000 Hz and a maximum amplitude of 10 nm to 500 m.