In the heat treatment process after welding

over-tempering can lead to worsening of the texture concerning the new type heat-resistant steel

namely P91 steel

making the hardness and chemical corrosion resistant behavior of P91 steel to be reduced.The causes resulting in over-tempering of P91 steel have been analysed

it is believed that the causes are short of guiding document or standard

unresonable constant-temperature time and temperature-reducing rate.The problems related to heat-treatment technology after welding of P91 steel have been discussed

it is put forward that the heat-treatment technology should take ensuring toughness and creep rupture strength of the weld joints as starting point

reasonably selecting the constant-temperature time as well as the temperature-rising rate and the temperature-reducing rate

preventing the voer-tempering phenomenon to be occurred.