钛合金改善X80管线钢中硫化物析出的研究

管线钢中的 MnS 对管线钢的韧性、焊接性能、应力腐蚀断裂等性能都有着不可忽视的影响.以不同 S 含量的 X80 管线钢为研究对象,通过加入不同的 Ti 含量控制 MnS 的生成,使其生成 Ti4 C2 S2 .运用 Factsage 软件模拟计算,探讨了 Ti 含量对 MnS 析出的影响,计算得到了不同 S 含量下 Ti4 C2 S2 析出时的临界 Ti 含量.在实验室条件下,制作了不同 Ti、S 含量下的试样,采用 SEM、EDS 观察不同条件下试样中夹杂物的形貌、尺寸和成分变化.研究表明,管线钢中加入 Ti 合金可以使 MnS 转化生成 Ti4 C2 S2 ,且 随 钢 中 S 含 量 的 提 高 其 要 求 转 化 生 成Ti4 C2 S2 的 Ti 含量也需提高.     

钢中氮含量对含硫齿轮钢硫化物影响的试验

某钢厂齿轮钢20CrMnTi(质量分数/%:0.17~0.23C,0.17~0.37Si,0.80~1.00Mn,0.025~0.035S,0.004~0.08Ti,1.10~1.25Cr)的生产工艺流程为90 t LD-LF-RH-CCM-150 mm×150 mm方坯连铸。通过热力学计算得到钢中的MnS和TiN均在液相线和固相线之间析出。试验研究钢中含不同氮含量情况下,钢中硫化物和氮化钛具有相互结合的变性效果。试验结果表明,当钢中氮质量分数约为0.005 5%时,TiN优先于MnS析出,钢中更多的硫化物夹杂以氮化钛为形核核心,形成硫化锰和氮化钛复合夹杂物,从而改善A类夹杂物尺寸和形貌,A类夹杂物呈短小、均匀分散分布态势,按GB/T 10561评定达到1.5级。     

含钛中碳钢中钛氧化物析出热力学分析

以含钛中碳钢为研究对象,从热力学的角度分析了含钛中碳钢中钛氧化物析出行为,结果表明:浇注温度为(1535±10)℃且钢中溶解氧含量大于0.003％(质量分数,余同)时,低钛中碳钢中的溶解Ti可与钢中的溶解氧反应生成Ti3O5、Ti2O3,生成TiO2、TiO夹杂的可能性较小;高钛中碳钢中的溶解Ti可与钢中的溶解氧反应生...     

Morphological Differences of MnS Inclusions in Medium-Carbon Steel with Different Manganese and Sulfur Contents

The morphology of MnS inclusion is one of the key elements influencing the machinability of steel. Herein, it is shown in the thermodynamic analysis results that the interaction coefficient causes a 1.2% deviation for the precipitation of MnS in low-sulfur-content steel (S1), while the deviation is 14% in high-sulfur steel (S2), and the content of C and Si is the main element causing the deviation. The microstructure of medium-carbon steel is mainly pearlite and ferrite. The increase of manganese and sulfur content leads to the decrease of ferrite content and increase of pearlite content. Almost all MnS inclusions in S1 are polyhedral, while S2 contains spherelike, cluster, and polyhedral MnS inclusions. Manganese and sulfur mainly affect the nucleation rate of MnS inclusion, where the number density of MnS in S2 is higher than that in S1, which increases the probability of viscous sintering of MnS inclusions in S2, and form spherelike- and rodlike-polycrystalline MnS particles. Polyhedron inclusions are mostly octahedron, and it is the final equilibrium morphology of sulfide in S1 and S2.     

硫含量对重轨钢中非金属夹杂物的影响

摘要：实际生产过程中由于原料和操作控制不精确,钢中硫含量和非金属夹杂物波动较大,严重影响钢的洁净度。为了准确控制重轨钢中硫化锰等非金属夹杂物的尺寸、形态和数量,在实验室开展了硫含量对重轨钢中非金属夹杂物的影响研究。钢中硫质量分数增至70×10-6、110×10-6、140×10-6后随炉冷却,采用全自动夹杂物分析仪对钢中非金属夹杂物进行统计,获得了硫含量与钢中非金属夹杂物成分、尺寸、形态和数量的关系。结果表明,钢中夹杂物大部分为以氧化物为形核核心的复合型MnS;随着硫含量的升高,复合型MnS、MnO-SiO2和MgO-Al2O3-SiO2-CaO型夹杂增多,CaO-SiO2和MgO-CaO-SiO2夹杂减少;夹杂物平均尺寸随硫含量的升高而增大,且不同尺寸的夹杂物均有所增加,尺寸为2~10μm增多最明显;硫质量分数为(70~140)×10-6的钢液凝固过程液相中都能单独析出MnS,且硫含量越高,MnS析出越早,含量越多。     

Effect of sulfur content on non metallic inclusions of heavy rail steel

Due to the inaccurate control of raw materials and operation in the actual production process, the sulfur content and non-metallic inclusions in the steel fluctuate greatly, which seriously affects the cleanliness of steel. To accurately control the size, shape and quantity of non-metallic inclusions such as manganese sulfide in heavy rail steel, the effect of sulfur content on non-metallic inclusions in heavy rail steel was studied in the laboratory. To investigate the changes of the number and morphology of non-metallic inclusions in steel under different sulfur contents, the sulfur content of test steel was increased to 70×10-6, 110×10-6 and 140×10-6, respectively. During the experiment, the test steel was heated and melted in a tubular furnace according to a certain heating rule, and then cooled naturally in the furnace. Subsequently, the non metallic inclusions in steel were scanned by automatic inclusions analyzer, and the relationship between sulfur content and the composition, size, form and quantity of non-metallic inclusions in steel was obtained. The results indicate that most of the inclusions in the steel are composite MnS with oxides as nucleating cores. With the increase of sulfur content, the quantity density of composite MnS, MnO-SiO2 and MgO-Al2O3-SiO2-CaO inclusions increase, while the CaO-SiO2 and MgO-CaO-SiO2 inclusions decrease. The average size of inclusions increases with the increase of sulfur content, and the number of inclusions with different sizes also increases, especially for inclusions with sizes of 2-10μm which increase obviously. During solidification, MnS can be separated from molten steel with sulfur content of (70-140)×10-6. In addition, the higher the sulfur content is, the earlier MnS inclusions precipitate and the more the MnS content is.     

Metallography of telluride on free cutting steel

The results of investigation and analysis of telluride and sulfides in free cutting steel containing tellurium and sulfur can be summerized as follows. No tellurium is found in steel matrix. All the tellurium exists in solid solution in manganese sulfide. The extra amount of tellurium in excess of the solubility in manganese sulfide exists as MnTe in steel. The tellurium content in manganese sulfide is 2.5 wt% on average, and the sulfur content in MnTe is about 3 wt %. In annealed steel, the content of iron solutionized in MnS (steel containing 1–2 % Mn) and in MnTe are both about 2 wt %. MnTe usually forms complex inclusions with MnS. The greater the Te/S, the higher the MnTe content in the complex inclusions. There is no single phase MnTe in steel with Te/S as high as 0.84. When steel is hot worked, MnTe deforms more easily than MnS. MnTe appears light grey in a bright field, and opaque in a dark field. In cast steel it is anisotropic and in forged steel it is isotropic under polarized light. In cold drawn steel, most of the MnS is anisotropic and remained so after annealing at 1100°C. If Te/S in steel is too high, the MnTe formed is prone to stretch in the working direction during press work. Hence, in so far as controlling the shape of the sulfide with the aid of tellurium is concerned, a Te/S of about 0.1 is appropriate. When the MnTe and MnS in steel are separated electrolytely in the four different solutions used in this work, the equilibrium potential of MnS is relatively positive, and that of MnTe is relatively negative in comparison with iron. When an organic solution (No. 3) is used, the MnS in steel can be almost completely and MnTe partly separated.     

X80管线钢探伤不合的原因分析

通过取样分析,研究了冶炼、轧制及轧后控冷工艺对X80管线钢板微观组织及探伤的影响。结果表明中心偏析、裂纹、MnS等夹杂物以及氢均对钢板的探伤结果造成不利影响。     

Ti处理的ELC-BH钢板的析出物研究

采用透射电镜研究了Ti处理的超低碳强度烘烤硬化钢板（简称ELC－BH钢板）的析出物，结果表明：在Ti处理的ELC－BH钢板中，不仅有两种类型的硫化物析出，即TiS和Ti4C2S2，而且有（Fe,Ti,P)粒子析出；二相粒子的析出顺序基本上：TiS,TiN-MnS,Ti4C2S2-TiC,(Fe,Ti,P),Ti加入量的确定应考虑它与N,S，C，Fe,P相结合的现象。     

控轧控冷工艺对抗H2 S腐蚀X70管线钢组织和性能的影响

根据抗H2S腐蚀X70管线钢的使用特点,采用低碳、超低硫、超低磷、控制Mn含量的技术思路,以控制MnS夹杂物数量和形态、铸坯的枝晶偏析与中心偏析。通过实验室的控轧控冷试验,分析了不同终轧温度和终冷温度对组织和性能的影响,试验结果表明,终轧温度为820℃和840℃时,均可获得准多边形铁素体+粒状贝氏体组织,随着终轧温度的降低,晶粒细化;随着终冷温度的降低,粒状贝氏体含量增加。通过实验室研究结果,确定了工业生产方案,并完成了工业试制。试验结果表明,在820℃终轧,400℃卷取可以获得组织为准多边形铁素体+粒状贝氏体、综合性能优良的产品,其抗HIC敏感测试为0,抗SSCC性能未失效。     

Genetic Analysis for Large TiN Inclusions in Wire Rod for Tire Cord Steel of SWRH82A

The law of element segregation of Ti, N, Mn and S, and the sequence of selective precipitation of TiN and MnS inclusions during solidification of molten steel of SWRH82A are studied on the basis of thermodynamics. The origin of large TiN inclusions which affect the titanium inclusions point penalty in SWRH82A wire rod is analyzed based on the research on the distribution characteristics of MnS and large size of TiN inclusions observed on metallographic specimen of SWRH82A steel wire rod. The solidification segregation ratio of Ti is far more than that of N, and the solidification segregation ratio of S is far more than that of Mn. In the range of cooling rate of the continuous casting production, the cooling rate of solidification has little effect on the segregation ratios of Ti, N, Mn and S. MnS inclusions will precipitate earlier than TiN inclusions during solidification of the molten steel of SWRH82A. The large TiN inclusion which is wrapped by MnS in the SWRH82A wire rod may be foreign inclusions and it is not precipitated product during solidification in the molten steel of SWRH82A.     

A Coupled Thermodynamic Model for Prediction of Inclusions Precipitation during Solidification of Heat-resistant Steel Containing Cerium

A coupled thermodynamic model of inclusions precipitation both in liquid and solid phase and microsegregation of solute elements during solidification of heat-resistant steel containing cerium was established.Then the model was validated by the SEM analysis of the industrial products.The type and amount of inclusions in solidification structure of 253 MA heat-resistant steel were predicted by the model,and the valuable results for the inclusions controlling in 253 MA steel were obtained.When the cerium addition increases,the types of inclusions transform from SiO2 and MnS to Ce2O3 and Ce2O2S in 253 MA steel and the precipitation temperature of SiO2 and MnS decreases.The inclusions CeS and CeN convert to Ce2O3 and Ce2O2S as the oxygen content increases and Ce2O3 and CeN convert to Ce2O2 S,Ce3S4,and MnS as the sulfur content increases.The formation temperature of SiO2 increases when the oxygen content increases and the MnS precipitation temperature increases when the sulfur content increases.There is only a small quantity of inclusions containing cerium in 253 MA steel with high cleanliness,i.e.,low oxygen and sulfur contents.By contrast,a mass of SiO2,MnS and Ce2O2 S are formed in steel when the oxygen and sulfur contents are high enough.The condition that MnS precipitates in 253 MA steel is 1.2 w[O]+w[S]0.01%and SiO2 precipitates when 2 w[O]+w[S]0.017%(w[S]0.005%)and w[O]0.006%(w[S]0.005%).     

超低碳汽车外板BH钢炼钢过程中夹杂物的演变

 为了研究超低碳钢炼钢过程中夹杂物的具体演变规律,利用夹杂物自动分析系统研究了硫质量分数分别为0.010%和0.015%的两炉次(S100炉次和S150炉次)超低碳汽车外板烘烤硬化钢(bake hardening steel,简称BH钢)从RH终点到铸坯过程中夹杂物形貌、成分、数量、尺寸的演变,并利用X射线荧光光谱仪和X射线衍射仪结合RH精炼渣和中间包覆盖剂熔渣的成分进行对比分析。结果表明,BH钢中夹杂物的主要类型为Al2O3、MnS、Al2O3+MnS和含硅类夹杂物(其中含硅类夹杂物主要是Al Si O夹杂,不包括纯硅、SiC、SiO2)。由于BH钢中锰和硫质量分数较高,凝固过程中MnS大量析出,使得铸坯中MnS夹杂物数量密度和夹杂物总数量密度显著增加。硫质量分数为0.010%和0.015%的两炉次钢在RH和中间包中MnS夹杂物数量密度无明显差异,由于MnS主要在凝固过程中析出,S150炉次在铸坯中的MnS明显多于S100炉次。精炼渣中w(（FeO+MnO）)较高,w(（CaO）)/w(（Al2O3）)比低,会导致RH终点Al2O3夹杂物较多。在浇注过程中,引流砂的流入会导致中间包覆盖剂熔渣中SiO2质量分数增高,造成钢液中Si Al O等夹杂物的数量密度明显增加。结晶器过程中Al2O3夹杂不断聚集长大、上浮去除,使铸坯中Al2O3和Al2O3+MnS夹杂物数量密度减少,尺寸增大。     

Ti-Mg复合脱氧和硫含量对钢中夹杂物特征及MnS析出行为的影响

采用扫描电镜/能谱仪表征了管线钢中夹杂物的形貌、尺寸、成分及数量,考察了不同Ti/Mg比的钢中夹杂物特征、硫含量及脱氧产物数量对MnS析出行为的影响,并进行了热力学计算.结果表明:Ti-Mg脱氧钢中夹杂物以MgO-Al₂O₃-Ti₂O₃、MgO-Ti₂O₃或MgO为核心,表面包裹或局部析出MnS,粒径小于1.3μm,数量为300~450 mm-2,形貌为圆形、多边形和方形;夹杂物中Ti/Mg原子数比为0.05~0.2时,夹杂物细小且近圆形;随硫含量减少,凝固过程中MnS析出倾向减小,MnS在夹杂物表面由包裹析出向局部析出转变,提高氧化物夹杂数量,有利于细小MnS的包裹或局部异质形核;Ti-Mg复合脱氧产物细小、弥散,可作为MnS异质形核核心,可同时降低MnS及氧化物的危害.      

管线钢硫化物钙处理技术分析

在对管线钢中硫化物的作用进行综合分析的基础上,结合莱钢的生产实践,利用冶金热力学原理,分析计算了管线钢硫化物的钙处理工艺条件,并对管线钢中的夹杂物进行了检测分析。结果表明,莱钢生产管线钢时,大部分炉次精炼终点氧质量分数高于理论计算钙处理所需的目标氧质量分数3.42×10-6,钢中钙质量分数未达到理论计算钙硫平衡时所需的量,硫化物夹杂物变性并不完全,钢中存在MnS、MnS CaS复合夹杂物。     

MnS precipitation in association with manganese silicate inclusions in Si/Mn deoxidized steel

When manganese silicate inclusions were formed during cooling from 1600 °C, manganese and sulfur contents in the manganese silicate inclusions were much lower than their equilibrium values within the steel matrix, i.e., the steel matrix was supersaturated with Mn and S against the inclusions. The formation of a Mn-depleted zone around an inclusion and the precipitation of a MnS phase on the inclusion were greatly affected by the thermal history of the steel. Slow cooling helped the formation of both the Mn-depleted zone and the MnS phase on the inclusion, but fast cooling suppressed it. Subsequent isothermal holding at 1200 °C diminished the existing Mn-depleted zone in slow-cooled steel, but created a Mn-depleted zone for fast-cooled steel. The mass transfer within an inclusion was sluggish, and the formation of a MnS phase is due to the local saturation of Mn and S at the outer part of an inclusion. It was suggested that the major factors affecting the formation of the Mn-depleted zone and the MnS phase are the cooling rate, isothermal holding, and the sulfide capacity of the inclusion.     

高硫硅钢硫化物析出行为及其微观组织和电磁性能变化#br#

为了探究高硫硅钢中的硫化物析出行为及其对钢的微观组织和电磁性能的影响,以便为工业化生产制定更为合理的硫含量控制标准,和采取更为有效措施以减轻炼钢生产的硫含量控制压力,结合0.25 %Si无取向硅钢,采用非水溶液电解提取+扫描电镜/透射电镜观察相结合的方法,研究了质量分数为0.006 8 %,0.010 2 %,0.025 5 %和0.035 3 %的硫含量条件下,钢中硫化物夹杂物的组成和存在形式,及其形貌、种类、尺寸、数量变化,以及相应的热轧、成品试样的微观组织和电磁性能变化。结果表明,随着钢中硫含量的增加,钢中的硫化物逐渐由MnS→MnS+Cu2S→Cu2S转变,数量逐渐增多,尺寸向高、低两个方向发展。相应的,导致了热轧再结晶组织的劣化和抑制了成品晶粒尺寸的长大。随着钢中硫含量的增加,钢的磁感、铁损劣化程度逐渐增大。钢中硫的质量分数平均每增加0.01 %,相应的,涡流损耗、磁滞损耗分别会劣化0.24 W/kg和0.41 W/kg,而磁感会劣化0.009 T。但是,在硫的质量分数为0.010 2 %时,铁损可以低于6.0 W/kg,而在硫的质量分数为0.025 5 %时,磁感可以高于1.75 T。据此,为设计更合理的硫含量控制标准提供了技术参考,在电磁性能满足高端用户市场需求的前提下,可以大幅度降低炼钢生产制造成本和提高炼钢生产效率。     

管线钢铸坯中硫化物特征及形成机理

 对管线钢铸坯中的硫化物特征进行了分析,并对其形成机理进行了讨论。发现从中间包钢液到铸坯,管线钢中夹杂物由低熔点的CaO Al2O3向CaS Al2O3类型转变,且夹杂物尺寸越小,在冷却过程中的转变越充分。根据形貌特征,含硫化物夹杂可分为以下几类,即硫化物在氧化物表面部分析出、硫化物半包裹氧化物、硫化物完全包裹氧化物、纯硫化物和在TiN上析出的硫化物。采用FactSage软件对冷却过程管线钢中的夹杂物转变进行了计算,发现随着温度的降低,液态钙铝酸盐夹杂物逐渐经历CaO·Al2O3→CaO·2Al2O3→CaO·6Al2O3→Al2O3的转变过程,同时CaS和MnS相也在冷却过程中析出,且MnS的析出温度低于CaS,这解释了铸坯中硫化物的特征和形成。     

钙处理对20CrMo齿轮钢硫化物夹杂的影响

在热力学计算的基础上,分析了20CrMo含硫齿轮钢钙处理的工艺条件,并对某厂钙处理后的含硫齿轮钢轧材进行了取样研究。结果表明,RH破空后钙处理的钢水中,硫化物和钙铝酸盐能结合生成复合纺锤状和低熔点夹杂;同时,钙处理前钢中w(O)控制在10×10-6以下,可使加入的钙充分对Al2O3、硫化物进行变性,并有利于形成以MnS为核心的氧硫复合夹杂;而且钢水铝脱氧后调整钢中w(AlS)=0.015%～0.025%,并在温度较高时喂Si-Ca线,可减少凝固过程中硫的偏析。该厂通过钙处理工艺生产的含硫齿轮钢夹杂物形貌良好,各项性能均达到客户的要求。     

深冲搪瓷钢DC03EK析出物及其抗鳞爆性能分析

对DC03EK深冲用冷轧搪瓷钢铸坯、热轧基料进行析出物检测,对其冷轧成品卷进行析出物、抗鳞爆敏感性TH值、成形极限FLD测试。结果表明,DC03EK深冲用冷轧搪瓷钢材料中存在弥散分布的Ti(C,N)、TiN、TiC、TiS、Ti4C2S2和极少量的MnS等析出物,铸坯中析出物颗粒较大,经热轧轧制较大颗粒析出物变小,经冷轧轧制及罩式退火后,析出物变得细小并弥散分布,使得DC03EK具有高的抗鳞爆敏感性TH值,同时又具有良好的成形性。