Establishment of technique for improving surface quality for recycling of steels in resource-cycled society

资源循环型社会钢材回收利用表面质量改善技术的建立

• 批准号: 17560650
• 负责人: NAGASAKI Chihiro
• 金额: $ 2.24万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2005
• 资助国家: 日本
• 起止时间: 2005 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17560650/
• 关键词: recycling of steel; steel scrap; hot surface cracking; surface hot shortness; addition of boron; oxidation; liquid embrittlement; 鉄のリサイクル

The suppression of surface cracking in hot rolling is important in recycling of steel. The surface cracking is caused by copper contained in steel scrap. The behavior of the hot surface cracking and the effect of boron on the suppression of the cracking were investigated in air and LNG combustion gas by using the steel containing 0.5%Cu and the steel containing 0.3%Cu and 0.04%Sn.The surface cracking of Sn-bearing steel is more intensive than that of Sn-free steel. Increasing the oxygen and steam contents accelerates promotes the surface cracking. The occurrence of the cracking is associated with the morphology and amount of Cu-enriched phase at the steel/scale interface. Addition of boron (B) to steel is effective in suppressing the surface cracking. The effect is the largest in air for Sn-free steel and is the smallest in LNG combustion gas for Sn-bearing steel. Addition of B does not change the oxidation behavior and has no effect on the morphology and amount of Cu-enriched phase at the steel/scale interface. Boron is segregated at the austenite grain boundaries of B-bearing steels. In the test for evaluating the easiness of the penetration of liquid Cu into grain boundaries of steel, the penetration is restrained with an increase in B content of steel or Cu-enriched phase. The increase in B content of steel surface can suppress the surface cracking in hot rolling. This is attributed to restraint of penetration of Cu-enriched phase into steel grain boundaries because the decrease in grain boundary energy due to the segregation of B and the increase in solid/liquid interface energy due to dissolution of B into Cu-enriched phase.

热轧过程中表面裂纹的抑制对钢材的回收利用具有重要意义。钢屑中含有铜，造成表面开裂。以含0.5%Cu的钢和含0.3%Cu、0.04%Sn的钢为研究对象，研究了在空气和LNG燃烧气体中的热表面开裂行为以及硼对其抑制开裂的作用。含锡钢的表面裂纹比不含锡钢的表面裂纹更强烈。氧气和蒸汽含量的增加加速了表面开裂。裂纹的发生与钢/垢界面上富cu相的形态和数量有关。在钢中加入硼(B)能有效抑制钢的表面开裂。无锡钢在空气中的影响最大，含锡钢在LNG燃烧气体中的影响最小。添加B不改变氧化行为，也不影响钢/垢界面上富cu相的形态和数量。硼在含硼钢的奥氏体晶界处偏析。在评价液态Cu渗进钢晶界的难易性的试验中，随着钢中B含量或富Cu相的增加，渗进受到抑制。增加钢表面B含量可以抑制热轧过程中的表面开裂。这是由于B的偏析使晶界能降低，而B溶入富cu相使固液界面能增加，从而抑制了富cu相向钢晶界的渗透。

项目成果

Effects of Boron and Tin on Surface Hot Shortness due to Copper in Low Carbon Steel

硼和锡对低碳钢中铜引起的表面热脆性的影响

• 发表时间: 2006
• 期刊: CAMP-ISIJ Vol.19・No.3
• 作者: Chihiro NAGASAKI;Kentaro ASAKURA;Toshihiko;KOSEKI;Koji Shibata
• 通讯作者: Koji Shibata

銅すず含有鋼の表面赤熱脆性に及ぼすボロン添加の効果

添加硼对含铜锡钢表面红脆性的影响

• 发表时间: 2005
• 期刊: 第56回塑性加工連合講演会講演論文集
• 作者: Chihiro NAGASAKI;Kentaro ASAKURA;Toshihiko;KOSEKI;Koji Shibata;Chihiro Nagasaki;長崎 千裕
• 通讯作者: 長崎 千裕

Suppression of Surface Cracking in Hot Working of Steels Containing Copper

含铜钢热加工表面裂纹的抑制

• 发表时间: 2005
• 期刊: Advanced Technology of Plasticity 2005
• 作者: Chihiro NAGASAKI;Kentaro ASAKURA;Toshihiko;KOSEKI;Koji Shibata;Chihiro Nagasaki
• 通讯作者: Chihiro Nagasaki