9Cr5Mo轧辊钢Φ500 mm连铸坯的生产实践

莱钢特钢事业部新区采用铁水+废钢→100 t电炉→双工位LF→双工位VD→圆坯连铸的流程生产Φ500 mm轧辊用钢9Cr5Mo。通过优化冶炼工艺、调整精炼渣系、强化保护浇注等措施,使9Cr5Mo钢的化学成分、低倍以及非金属夹杂物等各项指标均满足用户要求。     

模具钢4Cr5MoSiVl超声探伤缺陷的分析和工艺改进

山钢特钢事业部新区采用铁水+废钢→100 t电弧炉→双工位LF→双工位VD→圆坯连铸(Φ500 mm断面)→步进式加热炉→950轧机轧制的流程生产模具钢4Cr5MoSiV1,个别批次的4Cr5MoSiV1模具钢存在探伤不合格缺陷,通过对该批次探伤不合格缺陷部位运用超声波进行定位,对所取试样进行金相和扫描电镜分析,最终确认了铸坯的心部缺陷及轧制压缩比小,是造成该批次4Cr5MoSiV1钢探伤不合格的主要原因,并提出了相应的改进措施。     

模具钢4Cr5MoSiV1超声探伤缺陷的分析和工艺改进

山钢特钢事业部新区采用铁水+废钢→100 t电弧炉→双工位LF→双工位VD→圆坯连铸(Φ500 mm断面)→步进式加热炉→950轧机轧制的流程生产模具钢4Cr5MoSiV1,个别批次的4Cr5MoSiV1模具钢存在探伤不合格缺陷,通过对该批次探伤不合格缺陷部位运用超声波进行定位,对所取试样进行金相和扫描电镜分析,最终确认了铸坯的心部缺陷及轧制压缩比小,是造成该批次4Cr5MoSiV1钢探伤不合格的主要原因,并提出了相应的改进措施。     

100t UHP EAF-LF-VD-CC流程生产石油管用27CrMoNbTi热轧管坯钢工艺实践

特钢事业部新区采用铁水+废钢→100t电炉→双工位LF→双工位VD→圆坯连铸(650mm断面)→步进式加热炉→850轧机生产石油管用27CrMoNbTi热轧管坯,通过优化冶炼工艺、调整精炼渣系、保护浇注等措施,使27CrMoNbTi钢的各项指标均满足用户协议要求。     

Cr12MoV钢热变形行为研究

利用Gleeble 1500多功能热力模拟试验机对Cr12MoV钢金属塑性变形抗力进行试验研究,实测了不同变形温度、变形速率、变形程度下Cr12MoV钢的变形抗力,分析了各工艺参数对变形抗力的影响.回归计算得出Cr12MoV钢再结晶激活能;利用最小二乘法回归出峰值应力、峰值应变与Z参数的关系.     

CDC处理对Cr12MoV模具钢耐磨性的影响

研究了CDC处理对Cr12MoV钢组织与性能的影响。结果表明Cr12MoV钢在950℃及碳的质量分数为1．0％碳势条件下做CDC处理，材料表层细小碳化物的数量明显增加，细小碳化物颗粒的平均尺寸为400nm；材料显微硬度提高了Hm400左右，硬化层厚度为100μm。与常规处理的Cr12MoV钢相比，洛氏硬度提高HRC3，材料的耐磨性是常规处理的两倍以上。经实际生产考核，使用寿命是常规处理的两倍以上。     

550轧机新型导轮用钢Cr12MoV的研制与应用

导卫导轮的使用寿命是影响轧材尺寸精度的重要因素.通过550轧机生产Φ70 mm 20CrMnTiH齿轮钢的实践,根据4种导轮用钢T8、Cr16Ni3、Cr12MoV、Cr23Ni5Mo的性能试验和不同热处理工艺对Φ70 mm导轮使用寿命的影响,优选了Cr12 MoV钢(/％:1.45～1.55C、≤0.60Si、≤0.60Mn、12.00～13.00Cr、0.90 ～1.10Mo、0.90 ～1.10V)作为导轮材料并进行细化碳化物热处理和最终冷处理工艺,使Cr12MoV钢制成的导轮使用寿命达2000t,有效地保证钢材高精度轧制,减少尺寸废品.     

25Cr2Ni4MoV大型风机轴用钢的研制

针对25Cr2Ni4MoV大型风机轴用钢探伤要求较严格且不采用电渣重熔工艺生产的特点,分析了该钢种冶炼控制难点,制订了相对应的关键工艺控制点,确定采用双真空工艺生产25Cr2Ni4MoV风机轴用钢,经检测化学成分、力学性能、超声波探伤完全满足标准要求,完全可以替代电渣钢。     

Cr12MoV滚丝模模具热处理工艺研究

Cr12MoV材质冷作模具钢因为有着较好的淬透性,而且淬透后具有较高的耐磨性、淬火变形小等一些优点,因此常用来制作断面较大、耐磨性要求高的冷作模具,比如螺纹滚丝模等。模具在生产工作中,要使制件产生塑性变形模具要不断受到极大的压力、摩擦力和冲击力,因而对韧性、耐磨性、抗疲劳性能都有很高要求。本文对Cr12MoV钢滚丝模发生失效的原因进行分析,并针对上述原因进行了不同淬火工艺Cr12MoV钢组织和性能影响的实验研究。     

550轧机新型导轮用钢Crl2MoV的研制与应用

导卫导轮的使用寿命是影响轧材尺寸精度的重要因素。通过550轧机生产φ70 mm 20CrMnTiH齿轮钢的实践,根据4种导轮用钢T8、Cr16Ni3、Cr12MoV、Cr23Ni5Mo的性能试验和不同热处理工艺对φ70 mm导轮使用寿命的影响,优选了Cr12MoV钢(/%:1.45～1.55C、≤0.60Si、≤0.60Mn、12.00～13.00Cr、0.90～1.10Mo、0.90～1.10V)作为导轮材料并进行细化碳化物热处理和最终冷处理工艺,使Cr12MoV钢制成的导轮使用寿命达2 000 t,有效地保证钢材高精度轧制,减少尺寸废品。     

50Cr5MoV钢中非金属夹杂物及全氧

 对采用“EBT→LF→VD”工艺路线生产50Cr5MoV锻钢轧辊炼钢过程的全氧质量分数和夹杂物类型与数量进行了分析。结果表明：LF精炼后钢液中[w(T[O])]平均为0.004 7%,VD出站[w(T[O])]为0.001 4%,中间包[w(T[O])]为0.001 55%,铸坯[w(T[O])]为0.001 8%,轧材中[w(T[O])]降低至0.001 0%。LF精炼初期,钢中夹杂物主要是不规则的Al2O3夹杂,其中96.75%的夹杂物尺寸小于10 μm。LF精炼结束后,大量夹杂物转变成以CaO-Al2O3-SiO2为主要成分的0～1 0 μm复合氧化物夹杂。钢水从VD真空精炼炉向中间包转移过程中,由于保护性浇注效果差,二次氧化严重造成钢水夹杂逐渐增多,其中夹杂物主要为球形的[mCaO·nAl2O3]复合夹杂物。铸坯中99.65%的夹杂物尺寸小于10 μm,其中大部分为球形钙铝酸盐夹杂物,还有少量球状硅铝酸钙复合夹杂物。轧材中98.77%的夹杂物尺寸小于10 μm。通过对炼钢过程中各工序的工艺优化,可实现对夹杂物的有效控制, 从而确保50Cr5MoV合金铸钢的产品质量。     

高级别管线钢氮质量分数控制的研究与实践

通过对首钢京唐公司300t炼钢转炉→LF精炼→RH精炼→CC连铸各工序氮质量分数控制的研究,探讨影响钢中氮质量分数的因素和控制措施,结合生产实践,提出强化转炉冶炼操作、LF埋弧造渣、保证RH真空度和连铸全保护浇铸等工艺优化措施,尤其是控制LF精炼增氮和发挥RH精炼脱氮功能,改进后LF精炼增氮量小于0.001 0%;RH精炼可将氮质量分数脱至0.0030%,连铸增氮量平均为0.000 14%,首钢京唐管线钢成品氮质量分数平均为0.0031%,达到先进企业的水平。     

Constitutive Modeling for Elevated TemperatureFlow Behavior of 30Cr2Ni4MoV Ultra-super-crit- ical Rotor Steel

In order to perform numerical simulation of forging and determine the hot deformation processing parameters for 30Cr2Ni4MoV steel, the compressive deformation behaviors of 30Cr2Ni4MoV steel were investigated at the temperatures from 970 to 1270 ℃ and strain rates from 0. 001 to 0.1 s-1 on a Gleeble-3500 thermo-mechanical simulator. The flow stress constitutive equations of the work hardening-dynamical recovery period and dynamical recrystallization period were established for 30Cr2Ni4MoV steel. The stress-strain curves of 30Cr2Ni4MoV steel predicted by the proposed model well agreed with experimental results, which confirmed that the proposed equations can be used to determine the hot deformation processing parameters for 30Cr2Ni4MoV steel.     

Fe-5Mn-2Al-0.15C中锰钢连铸凝固偏析及粒子析出行为

为研究Fe-Mn-Al-C系中锰钢连铸凝固偏析及粒子析出特性,采用光学显微镜观察Fe-5Mn-2Al-0.15C中锰钢的显微组织,并通过Thermo-Calc热力学软件研究了其凝固模式、溶质元素偏析及粒子析出行为。结果表明,该中锰钢铸锭的显微组织主要为板条状马氏体,且含有少量铁素体;其凝固模式为L→L+δ→L+δ+γ→δ+γ→γ;Al元素的平衡分配系数大于1,发生负偏析,偏聚到δ-铁素体枝晶内部;而Mn、Nb、V、S等溶质元素发生正偏析,均偏聚到枝晶间。AlN主要在枝晶内析出,其析出温度为1 448 ℃;MnS、Nb和V的富集物主要在枝晶间析出,且MnS和Nb的富集物均在1 400 ℃以上开始析出,而V的富集物的析出温度为760 ℃。     

Study on microstructure and mechanical properties of martensitic stainless steel 6Cr15MoV

Martensitic stainless steel containing 12%-18%Cr have high hardness due to high carbon content. These steels are common utilized in quenching and tempering processes for knife and cutlery steel.The properties obtained in these materials are significantly influenced by matrix composition after heat treatment,especially as Cr and C content.Comprehensive considered the hardness and corrosion resistance,a new type martensitic stainless steel 6Cr15MoV has been developed.This study emphatic researches the effect of heat treatment processes on microstructure and mechanical properties of 6Cr15MoV martensitic stainless steel.Thermo-Calc software has been carried out to thermodynamic calculation;optical microscope（OM）,scanning electronic microscope（SEM） and transmission electron microscope（TEM） have been carried out to microstructure observation;hardness and impact toughness test have been carried out to evaluate the mechanical properties.Results show that the equilibrium carbide in 6Cr15MoV steel is M₂₃,C₆ carbide,and finely distributed of M₂₃C₆ carbides can be observed on annealed microstructure of 6Cr15MoV stainless steel.6Cr15MoV martensitic stainless steel has a wider quenching temperature range,the hardness value of steel 6Cr15MoV can reach to 60.8 -61.6 HRC when quenched at 1060 - 1100℃.Finely distributed carbides will exist in quenched microstructure,and effectively inhabit the growth of austenite grain.With the increasing of quenching temperature,the volume fraction of undissolved carbides will decrease.The excellent comprehensive mechanical properties can be obtained by quenched at 1060-1100℃with tempered at 100-150℃,and it is mainly due to the high carbon martensite and fine grain size.At these temperature ranges,the hardness will retain about 59.2-61.6 HRC and the Charpy U-notch impact toughness will retain about 17.3-20 J.The morphology of impact fracture surface of tested steel is small dimples with a small amount of cleavage planes.The area of cleavage planes increases with the increasing of tempering temperature.     

Effects of Mo Contents in Matrix on Microstructure and Properties of Vanadium Carbide Coating Formed by Thermal Diffusion Treatment

Thermal diffusion salt-bath vanadizing was finished for Crl2MoV die steel, in order to investigate the properties of vanadium carbide coatings related with the Mo contents in Crl2MoV die steel. Scanning electron micro- scopic observation reveals that Mo can decrease the growth rate of coating as a carbide forming element. Besides, Mo element can promote grain refinement of the coating. X-ray diffraction analysis shows that the different Mo contents have no influence on the phase structure of the coatings. Energy dispersive spectrum analysis and mechanical properties test show that Mo can diffuse into the coating and make a strengthening effect on the coating.     

1Cr11Ni2W2MoV钢持久性能机理分析及工艺改进

对540 MPa断裂时间小于100 h的真空感应炉冶炼+电渣重熔(Φ600 mm锭)+锻造成材工艺生产的90 mm×90 mm 1Cr11Ni2W2MoV钢分析表明：钢中回火马氏体组织含量不足及马氏体板条间碳化物析出不均匀是导致钢材强度及韧性偏低进而导致持久性能断裂时间小于100 h的原因,通过将锻坯加热温度由1130～1150℃降低到1000～1020℃,锻造90 mm×90 mm钢材的锻造方式由一火次成材变为两火次成材,终锻温度≥900℃,持久性能试样的回火温度由660～680℃降低到600～620℃,使1Cr11Ni2W2MoV钢540 MPa持久性能断裂时间从36～37 h提高到146～148 h。     

关于Cr12MoV冷作模具钢锻造工艺的研讨

对冷作模具钢Cr12MoV的试制及效果进行介绍     

Microstructure and Mechanical Properties of Martensitic Stainless Steel 6Crl5MoV

 Martensitic stainless steel containing Cr of 12% to 18% (mass percent) are common utilized in quenching and tempering processes for knife and cutlery steel. The properties obtained in these materials are significantly influenced by matrix composition after heat treatment, especially as Cr and C content. Comprehensive considered the hardness and corrosion resistance, a new type martensitic stainless steel 6Cr15MoV has been developed. The effect of heat treatment processes on microstructure and mechanical properties of 6Cr15MoV martensitic stainless steel is emphatically researched. Thermo-Calc software has been carried out to thermodynamic calculation; OM, SEM and TEM have been carried out to microstructure observation; hardness and impact toughness test have been carried out to evaluate the mechanical properties. Results show that the equilibrium carbide in 6Cr15MoV steel is M23C6 carbide, and the M23C6 carbides finely distributed in annealed microstructure. 6Cr15MoV martensitic stainless steel has a wider quenching temperature range, the hardness value of steel 6Cr15MoV can reach to HRC 608 to HRC 616 when quenched at 1060 to 1100 ℃. Finely distributed carbides will exist in quenched microstructure, and effectively inhabit the growth of austenite grain. With the increasing of quenching temperature, the volume fraction of undissolved carbides will decrease. The excellent comprehensive mechanical properties can be obtained by quenched at 1060 to 1100 ℃ with tempered at 100 to 150 ℃, and it is mainly due to the high carbon martensite and fine grain size. At these temperature ranges, the hardness will retain about HRC 592 to HRC 616 and the Charpy U-notch impact toughness will retain about 173 to 20 J. A lot of M23C6 carbides precipitated from martensite matrix, at the same time along the boundaries of martensite lathes which leading to the decrease of impact toughness when tempered at 500 to 540 ℃. The M3C precipitants also existed in the martensite matrix of test steel after tempered at 500 ℃, and the mean size of M3C precipitates is bigger than that of M23C6 precipitates.