钢中氮的控制及其对质量的影响

Control of Nitrogen in Steel and Its Effect on Quality of Steel

研究了钢水脱氧与不脱氧状况下的吸氮特性、钢中氮和钛形成氮化钛夹杂的条件及其对钢质量的影响,结果表明:钢中的氮化钛夹杂是在凝固过程中析出的,当N、Ti较高时,氮化钛在固液两相区析出,其尺寸较大,对钢的性能特别有害;将钢中的w(Ti)降到30×10-6,w(N)降到50×10-6以下,其氮化钛的析出温度将降到固相线以下,析出的夹杂尺寸细小,对钢性能的不利影响较小。随着N、Ti增加,钢的性能降低。钢水氧活度在200×10-6以上时钢水基本不吸氮,但脱氧良好的钢水裸露吸氮严重。

The[N] absorption behavior of killed steel and rimmed steel and conditions in which titanium nitride inclusions(TiN) are formed and effects of those inclusions on the quality of steel have been investigated. Results indicate that the TiN inclusions are precipitated in process of solidfication. When[N] and [Ti] content in steel is relatively higy the TiN inclusions, precipitated in the two phase (liquid and solid) region, are very harmful to the properties of steel due to their larger size. However as soon as w(Ti) and w(N) are reduced to 30 × 10-6 and 50×10-6 respectively the precipitated temperature of TiN inclusions will go down below the solid phase line and the TiN inclusions precipitated at this juncture are less harmful to properties of steel owing to their smaller size. With the increase of N and Ti contents in steel the steel properties are deteriorating. If ao rises to above 200 × 10-6 the nitrogen pick-up will probably come to an end,but the well-killed steel being exposed to the atmosphere will seriously pick up nitrogen.