二冷區(qū)溫度波動(dòng)下含Nb-Ti微合金鋼熱塑性行為研究
發(fā)布時(shí)間:2018-02-13 07:49
本文關(guān)鍵詞: 微合金鋼 溫度波動(dòng) 熱塑性 析出物 鐵素體 出處:《熱加工工藝》2016年22期 論文類(lèi)型:期刊論文
【摘要】:基于國(guó)內(nèi)某廠二冷區(qū)溫度波動(dòng)的實(shí)際生產(chǎn)工藝,利用Gleeble-3500熱模擬試驗(yàn)機(jī)對(duì)溫度波動(dòng)下的Nb-Ti微合金鋼進(jìn)行拉伸測(cè)試。采用掃描電鏡、光學(xué)顯微鏡對(duì)試樣斷口形貌及組織進(jìn)行觀察。結(jié)果表明:隨溫度波動(dòng)幅度(ΔT)增大,鑄坯脆性區(qū)右移。ΔT每升高25K,脆性區(qū)溫度提高50 K左右。低溫時(shí),鑄坯塑性幾乎不隨溫度波動(dòng)幅度變化而變化。隨拉伸溫度降低,試樣斷口由穿晶斷裂開(kāi)始向沿晶斷裂轉(zhuǎn)變;w及韌窩底部存在夾雜物或第二相粒子,為空穴形核提供條件,成為惡化鑄坯塑性的重要因素。隨溫度下降,鐵素體逐漸形成。在相同測(cè)試溫度下,溫度波動(dòng)越大對(duì)鐵素體含量的影響更加明顯。鐵素體體積分?jǐn)?shù)為36%時(shí),該鋼的熱塑性達(dá)到最低值。
[Abstract]:Based on the actual production process of temperature fluctuation in secondary cooling zone of a domestic factory, the tensile test of Nb-Ti microalloyed steel under temperature fluctuation was carried out by using Gleeble-3500 thermal simulator. The fracture morphology and microstructure of the specimens were observed by optical microscope. The results showed that the brittle zone shifted to the right with the increase of temperature fluctuation amplitude (螖 T). With the increase of 螖 T by 25 K, the temperature of brittle zone increased about 50 K. at low temperature. With the decrease of tensile temperature, the fracture of the billet changed from transgranular fracture to intergranular fracture. There were inclusions or second phase particles at the bottom of the matrix and dimple, which provided the condition for the cavitation nucleation. It becomes an important factor to worsen the plasticity of billet. With the decrease of temperature, ferrite gradually forms. At the same test temperature, the effect of temperature fluctuation on ferrite content is more obvious. When the volume fraction of ferrite is 36, The thermoplasticity of the steel reaches the lowest value.
【作者單位】: 華北理工大學(xué)冶金與能源學(xué)院;
【基金】:河北省自然科學(xué)基金(E2013209234)
【分類(lèi)號(hào)】:TG142.1
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