Ti-IF钢中夹杂物的行为

针对国内某厂的Ti-IF钢夹杂物的行为,研究了夹杂物的演变规律和铸坯中夹杂物的种类、大小、分布,分析了各类夹杂物的来源,提出了进一步减少夹杂物和改善Ti-IF钢连铸坯纯净度的措施.     

中厚板钢精炼过程夹杂物的转变

 通过工业试验研究了中厚板钢LF→钙处理→RH精炼过程中夹杂物的转变规律,并对钙处理过程夹杂物转变进行了热力学计算分析。结果表明：精炼过程钢中总氧质量分数降低,夹杂物数量密度降低,夹杂物平均尺寸升高;钙处理后夹杂物为CaO-MgO-Al2O3-CaS四元系;RH破空后夹杂物转变为CaO-MgO-Al2O3三元系,夹杂物中CaO质量分数降低,Al2O3质量分数升高;热力学计算表明,钙处理后钢液可直接生成CaS,也可与钙铝酸盐夹杂物反应生成CaS,RH破空后不能生成CaS。     

稀土Ce对18Cr-5Ni-4Cu-N奥氏体不锈钢热压缩性能的影响

采用Gleeble-1500D热模拟机对加入质量分数0.0063％Ce的18Cr-5Ni-4Cu-N奥氏体不锈钢进行热压缩测试,测定变形温度为1273～1473 K和应变速率为0.01～10s-1时热变形的应力应变曲线,采用Zener-Hol-lomon参数法构建高温本构方程,计算能量耗散图,并且采用场发射扫描电镜对高...     

410S不锈钢脱氧及冶炼过程的夹杂物

通过脱氧热力学计算410S铁素体不锈钢AOD还原后钢水中全氧质量分数,并对冶炼各工艺阶段所取钢样的全氧、夹杂物类型及形貌、渣样的化学成分进行检测,探究夹杂物的形成原因。结果表明,脱氧热力学计算的AOD还原后钢水中全氧质量分数跟检测值具有较好的一致性,随着还原硅质量分数的增加,钢水中全氧质量分数依次减小;随着冶炼过程的进行,钢液中全氧质量分数不断降低,夹杂物尺寸逐渐变小。AOD冶炼末期和LF冶炼末期夹杂物类型均主要为CaO-SiO2-MgO-Al2O3,但成分不同,跟这两个阶段炉渣的化学成分接近。连铸中间包中夹杂物成分跟钢液的温度降低有关。     

脱氧工艺对钢中夹杂物的影响

为明确不同脱氧剂加入顺序对钢中夹杂物的影响,对夹杂物的形成进行了热力学分析,并在1 873K下,在MoSi2电阻炉上用φ70 mm×100 mm MgO坩埚开展了2炉低碳合金钢A冶炼实验.热力学计算表明,Si-Mn脱氧主要形成SiO2夹杂物及少量2MnO· SiO2复合化合物,A1-Si脱氧主要形成Al2O3夹杂物,实验结果与热力学计算相互吻合.实验结果表明,先采用Si-Mn脱氧的1号工艺与先采用Al脱氧的2号工艺相比,夹杂物尺寸和面积百分比均较低.1号工艺终点夹杂物总数为168个/μm2,小于1.5φm的夹杂物占70％以上,夹杂物平均直径为1.2um.先弱脱氧后强脱氧的工艺更利于夹杂物的控制.     

武钢CSP集装箱钢夹杂物行为研究

通过对武钢CSP集装箱钢整个浇次全程跟踪取样,采用美国ASPEX公司的扫描电镜对所取钢样中夹杂物进行自动扫描检测,对LF—CSP钢中非金属夹杂物的主要来源、数量、尺寸分布、组成和类型的演变趋势进行了分析。     

G102Cr18Mo不锈轴承钢VIM-VAR冶炼过程夹杂物的演变

通过真空感应冶炼、真空自耗重熔,制备了 G102Cr18Mo不锈轴承钢锭,利用Aspex扫描电镜分析了夹杂物数量、尺寸、面积的变化规律,并采用SEM-EDS进一步观察夹杂物的元素分布.研究结果发现,不论是真空感应还是自耗重熔,夹杂物的组成变化不大,主要由硫化锰、铝酸钙、Al-Ca-Mn-(Ti)-O-S复合夹杂物3类夹...     

Microstructure and mechanical properties of a 3Cr-1.5Mo steel

Tensile and impact properties were determined for a steel (3 wt pct Cr-1.5 wt pct Mo-0.1 wt pct V-0.1 wt pct C) considered a candidate for elevated-temperature pressure-vessel applications. The steel was tested in two heat-treated conditions: normalized and tempered and quenched and tempered for various tempering conditions. Similar tempering treatments for the quenched and the normalized steels led to similar strengths. However, for the lowest tempering parameter used, the impact properties for the quenched-and-tempered steel exceeded those for the normalized-and-tempered steel, resulting in an excellent ductile-brittle transition temperature (-70 °C) and upper-shelf energy (225 J) for the quenched-and-tempered steel at a high strength (770 MPa ultimate tensile strength). Further tempering reduced the strength for the steel in both heat-treated conditions. The impact properties of the quenched steel were only slightly changed by further tempering, but those for the normalized steel improved, eventually equaling those for the quenched-and-tempered steel. The difference in impact properties after the two heat treatments was attributed to a difference in bainite microstructures.     

钇含量对铝脱氧含钛不锈钢中夹杂物的影响

 以T4003铁素体不锈钢为研究对象,采用热力学计算与实验室试验的方法,对钇质量分数为0、0.007 0%、0.014 0%和0.023 0%的不锈钢中夹杂物进行了分析,研究了稀土元素钇含量对T4003铁素体不锈钢中夹杂物的影响,总结了不同钇含量对钢中夹杂物影响的规律。首先通过计算夹杂物的生成吉布斯自由能变预测了钢中生成的夹杂物种类,总结了不同钇含量试验钢中不同夹杂物的生成吉布斯自由能变随温度的变化规律。计算结果与扫描电镜对钢中夹杂物的检测结果一致。研究表明,不含钇的T4003不锈钢中夹杂物主要为尺寸不均匀的均相TiN夹杂物及少量Al₂O₃、Mg-Al-O、Ca-Ti-O与TiN的非均相复合夹杂物,添加钇后钢中夹杂物主要为小尺寸的TiN和部分以Y₂O₃和Y₂O₂S为核心表面包裹TiN的复合夹杂物。随着钢中钇含量的增加,钢中夹杂物的总含量先增加后减少,夹杂物平均直径先减小后增大。夹杂物中氧化物的改性路径为MgAl₂O₄-CaO-TiO_x→MgAl₂O₄-Y₂O₃-(CaO-)TiO_x→Y₂O₃-TiO_x→Y₂O₃-Y₂O₂S及Y₂O₃和Y₂O₂S。试验钢中含TiN夹杂物的数密度与面积分数先增加后减少,平均直径先减小后增大。钇的加入使钢中小于4 μm的小尺寸含TiN夹杂物数量增多,但钇的加入量过高时,含TiN夹杂物的细化程度减弱。当钢中钇质量分数为0.007 0%与0.014 0%时,渣中含TiN夹杂物的尺寸明显减小,大尺寸的含TiN夹杂物数量显著减少。     

回火时间对0．16C－10Ni－14Co－1Cr－1Mo钢和0．23C－12Ni－14Co－3Cr－1Mo钢组织与性能的影响

研究了０．１６Ｃ－１０Ｎｉ－１４Ｃｏ－１Ｃｒ－１Ｍｏ（１６ＮｉＣｏ）钢在５１０℃和０．２３℃－１２Ｎｉ－１４Ｃｏ－３Ｃｒ－１Ｍｏ（２３ＮｉＣｏ）钢在４８２℃回火的组织与性能。随回火时间的延长，强度、硬度的降低主要是由于Ｍ_２Ｃ的粗化及与基体共格性降低所致。Ｍ_２Ｃ的粗化速度２３ＮｉＣｏ钢要小于１６ＮｉＣｏ钢。     

不同冶炼工艺的A286沉淀硬化不锈钢中夹杂物对比探讨

A286奥氏体沉淀硬化不锈钢(国内也称GH2132高温合金)是一种应用广泛的650 ℃以下使用的高温紧固件材料。该材料在实际生产使用中,使用了电炉+炉外精炼+电渣重熔(EAF+LF+ESR)和真空感应+真空自耗(VIM+VAR)两种冶炼生产工艺,而到目前为止国内对这两种工艺生产的A286不锈钢材料还未进行系统的对比研究。实验将以上两种冶炼工艺的A286试验钢作为研究对象,使用Aspex夹杂物分析仪、扫描电镜(SEM)等试验工具,对两种试验钢的组织,非金属夹杂物的种类、成分、粒径大小及分布、形态等差异及特点进行了对比研究。结果表明,EAF+LF+ESR冶炼的试验钢中的夹杂物数量、面积是VIM+VAR工艺试验钢的3倍以上;两种试验钢中的夹杂物均有TiC、TiN、Ti(C,N)等种类,前者的夹杂物以TiN夹杂物为主,且多为大尺寸链状,纵横比较大,形状较复杂,对材料室温力学性能和耐腐蚀性能不利;后者的夹杂物以TiC为主,尺寸较小且形状较简单。通过将A286试验钢中的N质量分数控制在0.001%以下,可以将含Ti夹杂物的数量、大小等控制在较低的水平。EAF+LF+ESR工艺由于自身工艺特点,试验钢中P含量较高,约为VIM+VAR工艺试验钢P含量的10倍,据资料可能有利于A286不锈钢的高温蠕变性能。研究结果可为在不同环境和服役要求下使用A286不锈钢提供技术参考。     

不同冶炼工艺的A286沉淀硬化不锈钢中夹杂物对比探讨

A286奥氏体沉淀硬化不锈钢(国内也称GH2132高温合金)是一种应用广泛的650 ℃以下使用的高温紧固件材料。该材料在实际生产使用中,使用了电炉+炉外精炼+电渣重熔(EAF+LF+ESR)和真空感应+真空自耗(VIM+VAR)两种冶炼生产工艺,而到目前为止国内对这两种工艺生产的A286不锈钢材料还未进行系统的对比研究。实验将以上两种冶炼工艺的A286试验钢作为研究对象,使用Aspex夹杂物分析仪、扫描电镜(SEM)等试验工具,对两种试验钢的组织,非金属夹杂物的种类、成分、粒径大小及分布、形态等差异及特点进行了对比研究。结果表明,EAF+LF+ESR冶炼的试验钢中的夹杂物数量、面积是VIM+VAR工艺试验钢的3倍以上;两种试验钢中的夹杂物均有TiC、TiN、Ti(C,N)等种类,前者的夹杂物以TiN夹杂物为主,且多为大尺寸链状,纵横比较大,形状较复杂,对材料室温力学性能和耐腐蚀性能不利;后者的夹杂物以TiC为主,尺寸较小且形状较简单。通过将A286试验钢中的N质量分数控制在0.001%以下,可以将含Ti夹杂物的数量、大小等控制在较低的水平。EAF+LF+ESR工艺由于自身工艺特点,试验钢中P含量较高,约为VIM+VAR工艺试验钢P含量的10倍,据资料可能有利于A286不锈钢的高温蠕变性能。研究结果可为在不同环境和服役要求下使用A286不锈钢提供技术参考。     

电磁搅拌对304不锈钢电渣锭夹杂物的影响

摘要：通过自行设计的带电磁搅拌的电渣重熔炉,以304奥氏体不锈钢为研究对象,详细分析外加磁场对电渣锭夹杂物数量、大小以及类型的影响。采用氧氮氢分析仪检测氧、氮气体含量,采用扫描电镜观察夹杂物的形貌、组成,并采用ASPEX分析夹杂物的尺寸变化。结果表明,无论是否外加磁场,电渣锭中的氧含量都有所增加,从自耗电极中氧质量分数由23.7×10-6最高增至64.70×10-6;而相比于自耗电极,氮含量略微降低,其质量分数从675.5×10-6降低至659.33×10-6;无论是否加入磁场,电渣锭中的夹杂物种类并无变化,主要由Al2O3、MnS-Al2O3、Al-Si-O、Al-Ca-O、Al-Si-Ca-O、Al-Mg-O及其他夹杂物组成;在施加磁场后,电渣锭中的大颗粒夹杂物数量有所减少。外加磁场强度较小时并不能有效去除夹杂物,反而会增加夹杂物的数量,当磁感应强度为10mT时,夹杂物数量相比于未加磁场时增加了4260%,但是最大尺寸有所减小。     

SUS430不锈钢夹杂物的变化规律研究

对采用EAF-AOD-LF-CC工艺路线生产SUS430不锈钢炼钢过程夹杂物的成分组成和形貌、尺寸变化进行了分析,结果表明,SUS430不锈钢中主要形成呈球状或不规则球状分布的硅酸盐复合夹杂物,其变形能力较差。随着LF精炼和连铸过程的进行,SUS430不锈钢钢水中夹杂物的平均直径呈逐渐减小的趋势,铸坯夹杂物的平均直径为3.4μm左右,5μm以上的夹杂物占夹杂物总数的1%以下。变形能力较差的硅酸盐夹杂和镁铝尖晶石夹杂是引起SUS430不锈钢冷轧板表面线鳞缺陷的重要原因,采用钙处理和复合脱氧工艺,对改善SUS430不锈钢冷轧板的表面线鳞缺陷有利。     

Effect of electromagnetic stirring on inclusions in 304 stainless steel electroslag ingot

Based the self designed electroslag remelting furnace with electromagnetic stirring, the effect of external magnetic field on the number, size and type of inclusions in 304 stainless steel electroslag ingot was analyzed in detail. The content of oxygen and nitrogen in electroslag ingot was analyzed by ONH analyzer, and the morphology and element distribution of inclusions were observed by SEM. Finally, the ASPEX was used to analyse the size, number and type of inclusions. The results show that the oxygen content in electroslag ingot increases from 23.7×10-6 in consumable electrode to 64.70×10-6 whether magnetic field is applied or not, and the oxygen content increases to 67.4×10-6 at most from 23.7×10-6 in the electrode. But the nitrogen content in electroslag ingot decreased slightly to 659.3×10-6 from 675.5×10-6 in the electrode. The magnetic field has almost no effect on the type of inclusions, which mainly includes Al2O3, MnS-Al2O3, Al-Si-O, Al-Ca-O, Al-Si-Ca-O, Al-Mg-O and other inclusions. After the magnetic field is applied, the amount of large inclusions in electroslag ingot decreases, but the total number of inclusions increases when the magnetic induction intensity is small. When the magnetic induction intensity is 10 mT, the number of inclusions increases by 42.60%, but the maximum size of the inclusions decreases.     

冶炼工艺对15-5PH不锈钢疲劳性能的影响

 为了研究冶炼工艺对15-5PH不锈钢疲劳性能的影响,通过ASPEX夹杂物分析、拉压疲劳试验和扫描电镜等手段并结合裂纹扩展速率试验,研究了冶炼工艺对15-5PH不锈钢中夹杂物的粒径分布和疲劳性能的影响,并对比了两种试验钢裂纹扩展速率的大小。结果表明,VIM+VAR工艺冶炼的1号试验钢总氧质量分数较低,夹杂物尺寸较小且质量分数较低,1号试验钢的疲劳强度比单真空工艺冶炼的2号试验钢高30 MPa,通过疲劳断口SEM观察,1号试验钢在表面基体起裂,2号试验钢的裂纹源是次表面的Al₂O₃夹杂物;相同条件下,1号试验钢裂纹扩展速率大于2号试验钢。     

钙处理对430不锈钢板坯夹杂物的影响

通过热力学计算分析了430铁素体不锈钢钙处理后在生成液态夹杂物区间内钢中钙质量分数和铝质量分数的关系,并对430铁素体不锈钢未采用钙处理和采用钙处理板坯中夹杂物类型、数量进行了对比,分析了钙处理夹杂物变性过程。结果表明,精炼过程喂入硅钙线可以得到理想的钙处理效果。钙处理后430钢水中高熔点的Al_2O_3和低变性的CaO-SiO_2-Al_2O_3-MgO夹杂物得到良好变性,夹杂物数量比未采用钙处理时明显减少,夹杂物尺寸都小于15μm。CaO和Al_2O_3两者通过发生化学反应变性为低熔点的液态夹杂物。     

Isothermal formation of quasicrystalline precipitates and their effect on strength in a 12Cr-9Ni-4Mo maraging stainless steel

A new type of maraging steel, Sandvik 1RK91, intended for use in surgical applications has recently been developed at Sandvik Steel, Sandviken, Sweden. In the present article, a comparison was made between this steel and a traditional maraging steel with respect to mechanical and physical properties after tempering treatments in the temperature range 375 °C to 580 °C. The tempering behavior was studied by analyzing hardness, resistivity, and volume fraction of magnetic phase. Sandvik 1RK91 showed a remarkably high microstructural stability against overaging, softening being observed only at 580 °C. In comparison with the reference steel, the hardness of Sandvik 1RK91 was found to be considerably higher in the whole range of temperatures, with the maximum values corresponding to a strength of 3000 MPa for the smallest dimensions of wire. A detailed microstructural investigation of precipitation reactions in Sandvik 1RK91 revealed a new type of precipitate at 475 °C that was found to be of a quasicrystalline nature. These precipitates, which were found to give the major contribution to particle strengthening after tempering at 475 °C, showed a close resemblance to intermetallic trigonalR phase with a chemical composition of about 50 pct molybdenum, 15 pct chromium, 30 pct iron, and 5 pct silicon. The similarity between the quasicrystalline precipitates andR phase was reflected as a second-order transition occurring at about 525 °C. The extremely high strength in 1RK91 can be ascribed to the quasicrystalline nature of the precipitates because of impeded particle shearing.     

Hot tearing susceptibility of Fe-20.96 Cr-2.13 Ni-0.15 N-4.76 Mn-0.01 Mo duplex stainless steel

The hot tearing susceptibility of a Fe-20.96Cr-2.13Ni-0.15N-4.76Mn-0.01 Mo duplex stainless steel was investigated using method of constrained solidification shrinkage in one dimension.An apparatus for realtime measuring the contraction stress and temperature during solidification was developed,which can achieve the in-situ observation of melting and solidification and avoid the large temperature gradient of casting under the condition of pouring.The results show that the contraction stress increases significantly when the core temperature of casting reaches the liquidus temperature.The contraction stress is released when the core temperature of casting reaches 1456°C.At this temperature,the hot tearing susceptibility of duplex stainless steel is the largest.With decreasing the core temperature to 1363°C,the slope of contraction stress increases,which is related to the ferrite-to-austenite transformation.