回火溫度對(duì)26CrMo鉆桿鋼組織性能的影響

回火溫度對(duì)26CrMo鉆桿鋼組織性能的影響Effects of Tempering Temperature on Microstructure and Mechanical Properties of Drill Pipe Steel 26CrMo

采用力學(xué)性能測(cè)試、組織觀察等方法研究回火溫度對(duì)26CrMo鋼顯微組織和力學(xué)性能影響。結(jié)果表明，26CrMo鋼經(jīng)540~690 ℃回火，隨回火溫度升高，顯微組織中α相基體逐漸發(fā)生回復(fù)與再結(jié)晶，組織中馬氏體形態(tài)逐漸消失，碳化物先在馬氏體板條邊界呈片狀或棒狀析出，逐漸演變?yōu)轭w粒狀彌散分布，690 ℃時(shí)碳化物在晶界聚集長(zhǎng)大、球化。隨回火溫度升高，26CrMo鋼強(qiáng)度逐漸降低，塑性、韌性逐漸增大；不同回火條件下，抗拉強(qiáng)度、屈服強(qiáng)度、延伸率和沖擊功滿足API5DP標(biāo)準(zhǔn)中各級(jí)別鉆桿要求。隨回火溫度升高，26CrMo鋼總沖擊功、起裂功和裂紋擴(kuò)展功均逐漸增大，裂紋擴(kuò)展功是起裂功的3倍以上，且兩者比值變化不明顯，表現(xiàn)出良好的抗裂紋擴(kuò)展能力。不同回火溫度下沖擊性能的變化與其強(qiáng)度、塑性變化密切相關(guān)，沖擊韌性好壞主要由塑性大小決定。

The effects of tempering temperature on microstructure and mechanical properties of steel 26CrMo were studied based on mechanical property tests and microstructure observation. The results show that α phase matrix gradually occurs recovery and recrystallization with the increasing temperature during 540~690 ℃ temper process, martensite morphology fade away gradually, flake or rocklike carbides separate out along the martensite boundaries, and then change into granulated dispersed distribution, at 690℃ tempering carbides happen aggregation and growth on grain boundaries. With tempering temperature increasing, the strength of 26CrMo steel is gradually reducing, plasticity and toughness are gradually increasing. The tensile property and impact energy can meet all different grade drill pipe requirements in API 5DP standard with different tempering condition. The total impact energy, crack initiation energy and crack propagation energy of 26CrMo steel are gradually increasing with the tempering temperature rising, the value of crack propagation energy is three times of crack initiation energy which shows great anti-crack propagation capability, but their ratio has no obvious change. The change of impact property is closely related to the strength and plasticity change, impact toughness stand or fall depends on high or low plasticity.

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