本文關(guān)鍵詞： 馬氏體時效鋼 時效溫度 延遲斷裂傾向 缺口敏感性　出處：《鋼鐵研究總院》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：氫致靜載延遲斷裂是載荷低于設(shè)計許可應(yīng)力的一種突發(fā)性斷裂,其后果往往是災(zāi)難性的,馬氏體時效鋼重載構(gòu)件曾發(fā)生過較多的事故,為此許多研究學(xué)者對比研究了馬氏體時效(不銹)鋼欠時效、峰時效和過時效處理在H2、飽和H2S溶液等氫環(huán)境下延遲斷裂行為,證明欠時效處理后氫致延遲斷裂抗力最低。然而,馬氏體時效(不銹)鋼可容忍的極限氫含量極低,在正常的冶煉和熱加工后是否發(fā)生氫致延遲斷裂未進(jìn)行過研究,本文研究了時效溫度對馬氏體時效(不銹)鋼延遲斷裂抗力的影響。研究選用18Ni350馬氏體時效鋼和Cr-Ni-Mo-Ti馬氏體時效不銹鋼棒材,以及2.0mmm厚冷軋帶材,原材料經(jīng)雙真空冶煉,氫含量不高于2.0ppm,時效溫度(420～540℃)覆蓋了欠時效、峰時效和過時效。采用缺口拉伸試驗(yàn),對比拉伸位移速率0.15mm/min(快拉伸)和0.0015～0.005mm/min(慢拉伸)的斷裂強(qiáng)度,并用此評價氫致延遲斷裂傾向,研究主要得到下述結(jié)果：18Ni350馬氏體時效鋼420。C和450℃欠時效態(tài)強(qiáng)度較低,但缺口敏感性較高,氫含量低于1.Oppm情況下仍表現(xiàn)出較高的氫致延遲斷裂傾向；480℃時效強(qiáng)度略低于510℃峰時效,但缺口敏感性較低,缺口抗拉強(qiáng)度高出峰時效100MPa以上；540℃過時效強(qiáng)度下降,但未降低缺口敏感性,盡管氫含量不變,480～540℃時效未表現(xiàn)出氫致延遲斷裂傾向。Cr-Ni-Mo-Ti馬氏體時效不銹鋼棒材缺口快拉伸(0.15mm/min)在480～500℃時效出現(xiàn)強(qiáng)度峰值；氫含量不高于2.0ppm情況下,420℃和440℃欠時效發(fā)生氫致延遲斷裂,但460～520℃時效則未表現(xiàn)出氫致延遲斷裂傾向。Cr-Ni-Mo-Ti馬氏體時效不銹鋼冷軋帶材在440～520℃之間時效光滑拉伸強(qiáng)度下降,而熱軋帶材在480-500℃之間時效出現(xiàn)強(qiáng)度峰；另一方面,冷軋變形增大過時效傾向,因此冷軋變形具有增強(qiáng)時效動力學(xué)作用。冷軋變形顯著提高時效后的強(qiáng)度,但并未增大缺口敏感性,尤其是460℃以上時效,冷軋帶材缺口敏感性指數(shù)接近于熱軋帶材。盡管冷軋帶材強(qiáng)度提高230～460MPa,但480℃以上時效后并未表現(xiàn)出延遲斷裂傾向,證明冷變形是提高馬氏體時效不銹鋼強(qiáng)度的可靠方法。
[Abstract]:Hydrogen induced static load delayed fracture is a kind of sudden fracture whose load is lower than the design allowable stress, and its consequence is often catastrophic. There have been many accidents in maraging steel heavy load members. For this reason, many researchers have comparatively studied the delayed fracture behavior of martensite aged (stainless) steel under H _ 2, H _ 2S saturated H _ 2S solution and peak aging treatment. It is proved that the hydrogen delayed fracture resistance is the lowest after underaging treatment. The tolerable limit hydrogen content of maraging (stainless) steel is very low. Whether hydrogen induced delayed fracture occurs after normal smelting and hot working has not been studied. In this paper, the effect of aging temperature on the delayed fracture resistance of martensite aging steel (stainless steel) is studied. 18Ni350 maraging steel and Cr-Ni-Mo-Ti maraging stainless steel bar and 2.0 mm thick cold rolled strip are used in the study, and the raw materials are smelted in double vacuum. The underaging, peak aging and overaging were covered with hydrogen content of not more than 2.0 ppm. The tensile strength of 0.15mm / min (fast tension) and 0.00155mm / min (slow tension) were compared with the tensile displacement rate of 0.15mm / min (fast tension) and 0.00155mm / min (slow tension) respectively, and the tendency of hydrogen induced delayed fracture was evaluated by this method. The main results are as follows: 420.C and 450 鈩，

本文編號：1528767