In order to realize the domestic production of UNS N09 925 alloy in the oilfield servic

e industry， the "VIM+VAR" process was successfully used to smelt

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508 mm ingot of UNS N09925 alloy， and the forging process optimization test of

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228.6 mm （9Inch） forged bar was carried out. In order to optimize the forging heating regime， the grain size growth of UNS N09925 alloy in hot forging state was studied from 950 ℃ to 1 150 ℃ using

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131 mm forging bar as raw material. The experiment shows that the inflection point temperature of grain growth of UNS N09925 alloy is 1 020 ℃. When the heating temperature is above 1 100 ℃， the grai

n grows rapidly. Based on the rule of forging grain size growth， forging process experiments were carried out under two different heating regimes of 1 120 ℃-1 160 ℃ and 1 020 ℃-1 100 ℃. The results showed that the two rods of

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228.6 mm large round forging produced by "low temperature heating" at 1 020 ℃-1 100 ℃ had the best microstructure in forged and solid solution state. Moreover， through the tests of low and high microstructure， tensile properties， impact properties and cross section hardness， the product met the requirements of various indicators in API 6A CRA， and the TTF ratio of slow strain corrosion test reached 0.88 and RA ratio reached 0.69， meeting the requirements of TTF ratio ≥0.7 and RA ratio ≥0.6 in the industry standard.