Influence of Mo Content on Microstructure and Mechanical Properties of Fire-Resistant Construction Steel

In order to ensure fire-resistant property of the steel under the condition of the least molybdenum content,effects of molybdenum on microstructure and properties of the fire-resistant construction steel,specially on high temperature strength were investigated.The results show that the room temperature and high temperature strength of the steel is enhanced due to increased Mo content but the impact toughness deteriorates at the same time.The fraction of bainite in the microstructure increases with increasing Mo content while the fractions of polygonal ferrite and pearlite decrease.Comparing with the steel of adding Nb alone,it was obvious that combined addition of Mo and Nb could provide better effect in high temperature strengthening.Addition of 0.25mass% Mo in the steel containing Nb could meet fire-resistant requirements of the construction steel and provide better economical effectiveness.     

耐火钢的性能及工艺研究

测定了耐火钢的CCT曲线,研究了耐火钢的性能,包括室温和高温拉伸性能、系列温度下的冲击性能、应变时效性能等;探讨了终轧温度、冷却速度、回火对耐火钢性能的影响.结果表明:试验钢的综合性能完全满足了设计指标的要求,生产工艺的研究工作为耐火钢的工业生产提供了有益的参考.     

轧制工艺对Ti微合金化马氏体钢力学性能的影响

 通过采用扫描电镜、透射电镜、X射线衍射以及相分析等手段来观察组织的微观结构和对析出相的验证,研究轧制温度对轧态Ti微合金化马氏体钢强度的影响。研究结果表明,通过降低轧制温度可以明显提高含Ti马氏体钢的屈服强度,这主要是因为当轧制温度从1100℃降低到950℃过程中,形变诱导析出大量的TiC析出相,随着轧制温度的降低,析出相数量明显增加,并且平均尺寸也逐渐变小。马氏体中大量存在的1～20nm范围的析出相可以起到明显的析出强化作用。     

钒对低钼耐火钢组织及性能的影响

采用扫描、透射电镜对不同钒含量的低钼耐火钢的组织进行分析,确定出热轧状态的组织为先共析铁素体、粒状组织/粒状贝氏体.同时还发现V的析出物在热轧钢中主要固溶于铁素体基体内,600 ℃重新加热时以细小的V(C,N)弥散析出,从而起到高温析出强化的作用.     

铜单一元素合金化热轧钢板的组织与性能

研究了铜单一合金化高纯净热轧钢板在时效退火前后的组织与性能的关系.结果表明,铜具有明显的时效强化作用,在时效过程中铜的析出优先于钢板的再结晶,同时高纯净基体使钢材保持了良好的塑性.分析表明,铜单一合金化高纯净钢具有良好的发展前景.     

Effect of Finish Rolling Temperature on Microstructure and Mechanical Properties of High Grade Pipeline Steel

The correlation among finish rolling temperature (FRT),microstructure and mechanical property of the high grade pipeline steel was investigated in this study.The microstructure of the steels with different finish rolling temperatures was observed with scanning electronic microscope (SEM) and transmission electronic microscope (TEM).The martensite/austenite (M/A) islands distribution was fixed by colour metallography,and the mechanical properties of the steels were tested with quasi-static tensile testing machine.The result shows that the fraction of M/A island increased with the finish rolling temperature decreasing,and when the finish rolling temperature is 800℃,the mechanical properties are the best.     

终轧温度对ELC-BH板组织和性能的影响

研究了热轧终轧温度(FT)对超低碳高强度烘烤硬化钢板(简称ELC-BH板)组织和性能的影响,结果表明:①两相区终轧形成的混晶组织是导致退火板相似文献   

Effect of Ti Addition on Yield Strength of Low-Mo Fire-Resistant Steel at Elevated Temperatures

Herein, a series of low-Mo (0.2 wt%) fire-resistant steels with varying amounts of Ti (0.008–0.13 wt%) are investigated to study the effects of Ti on yield strength at elevated temperatures. At room temperature (RT), precipitation strengthening by nanoscale TiC precipitates is found to be the major factor for the enhanced strength. The amount of TiC precipitates and both the yield and tensile strengths increase monotonically with the Ti content. However, the yield strength ratio (YS at 600 °C divided by YS at RT) of the steel with the highest Ti content (0.13 wt%) is significantly reduced to 0.6. In contrast, the YS ratio of the steels with Ti content in the range of 0.008–0.087 wt% remains above 0.7 and increases with Ti content. The difference between the steels lies in the B content and the resultant bainite volume fraction. The steel with 0.13 wt% Ti does not contain B and has only 4% bainite, whereas the other steels contain 20 ppm B and approximately 60% bainite. Hence, a microstructure with a sufficient fraction of bainite is required to ensure strength at elevated temperatures. The properties can be further improved by Ti precipitation strengthening.     

宝钢1880mm热轧试生产DP600双相钢的组织性能

采用Si-Mn系简单成分设计,充分发挥宝钢1 880 mm热连轧机组的密集冷却能力和卷取能力,通过密集水冷—空冷—水冷的三段式冷却模式和低温卷取,成功实现在1 880 mm机组工业试生产600 MPa级热轧双相钢。结果表明,通过合理的冷却速度、中间待温温度和待温时间配合,试验钢可获得铁素体和马氏体比例适合的双相组织,力学性能满足600 MPa级双相钢设计要求;同时试验发现,冷却和卷取工艺显著影响双相钢的微观组织和性能,因轧速变化造成钢卷头尾冷却条件不一致,导致钢卷不同位置力学性能波动较大。     

Effects of Finish Rolling Temperature on Microstructure and Mechanical Properties of Ferritic-Rolled P-Added High Strength Interstitial-Free Steel Sheets

  The steels were rolled at 3 different finishing temperatures. The mechanical properties were tested by tensile tests. The results show that as finish rolling temperature decreases from 620 to 560 ℃ in ferrite region, the deep drawability of ferritic rolled P added high strength IF steels is improved, and r value rises from 114 to 137. Finish rolling temperature (FT) has less influence on other mechanical properties, such as yield strength, tensile strength and elongation. Microstructures of hot rolled and annealed steel sheets and precipitates of annealed steel sheets were also analyzed.     

Q235H型钢轧后强冷工艺对组织和性能的影响

轧后经强冷的Q235H型钢铁素体晶粒大小和机械性能与轧后奥氏体晶粒大小和温降速度密切相关.以马钢现有轧后强冷系统为试验设备,以现有常规轧制工艺为条件,在水压和水流密度不变的前提下,通过改变冷却段的长度,即改变强冷时间,得到Q235H型钢不同温降速度、晶粒大小和机械强度及分布,同时验证了Hall-Petch公式的正确性,...     

淬火温度对Q-P钢组织和性能的影响

 采用盐浴的方法模拟Q-P钢的热处理工艺,对钢的组织和性能进行分析和研究。其结果表明,淬火配分组织主要为板条马氏体和残留奥氏体,并随淬火温度升高马氏体含量降低,奥氏体含量升高,从而降低钢的强度,提高塑性,拉伸断口呈现典型的韧窝状形貌,当淬火温度为250℃时,得到最高的强塑积为26224MPa·%。     

Microstructure and Mechanical Properties of Nb-Microalloyed X100 High Deformability Pipeline Steel

A low carbon Nb-microalloyed high deformability pipeline steel with X100 grade has been processed by TMCP and followed two-stage cooling process.The microstructure is characterized by ferrite/bainite multiphase.The effective grain size is 1.85μm in average.The volume of ferrite is about 10-15% and the grains sizes are mostly less than 5μm.The bainite consists of granular-bainite and lath-bainite,with M/A islands finely dispersed.The longitudinal tensile yield strength,uniform elongation,yield ratio are 647MPa,7.6% and 0.78,respectively.Ferrite/bainite multiphase have large strain hardenability that resulting high strength and high deformability combination.Precipitation of Nb also improves the strength and uniform deformability by precipitation strengthening and grain refinement.     

遇火强化型耐火钢Q420FRE的物理冶金原理与力学性能

 根据微合金纳米第二相在加热升温过程中的析出特点,充分发挥微合金第二相的强化作用,提出了遇火强化型耐火钢技术新思路。与传统耐火钢相比,通过降低钼含量,可以降低钢材成本。遇火强化型耐火钢的生产工艺路径为热轧＋快速冷却,抑制微合金纳米第二相在热轧板冷却过程中析出的同时,获得中低温转变组织。工业试制Nb-V-Ti-Mo复合微合金化遇火强化型耐火钢Q420FRE组织类型为细小的粒状贝氏体,力学性能满足耐火钢标准GB/T 28415—2012的要求,其中室温伸长率和－40 ℃低温冲击韧性优异。经计算,工业试制的遇火强化型耐火钢Q420FRE在600～700 ℃下的纳米MC相沉淀强化增量超过50 MPa。模拟测试表明,工业试制Q420FRE的耐火极限温度接近650 ℃,600 ℃高温回火3 h不失效,空冷至室温后屈服强度上升,具有二次耐火性。     

H13改进型热作模具钢的组织与性能

 研究了高锰型马氏体热作模具钢SDH3-Mod的室温冲击韧性、回火稳定性和热疲劳性能,并结合透射电镜(TEM)分析了锰对其微观组织的影响。结果表明：SDH3-Mod钢回火组织中残余奥氏体以薄膜状存在于马氏体板条间,提高冲击韧性,延缓裂纹扩展;同时,锰在高温时阻碍碳化物粗化长大和延迟基体的回复再结晶,提高抗回火软化能力和热疲劳性能,使SDH3-Mod性能优于H13。     

Effect of Controlled Cooling After Hot Rolling on Mechanical Properties of Hot Rolled TRIP Steel

A three-step cooling pattern on the runout table（ROT）was conducted for the hot rolled TRIP steel.Microstructural evolution during thermomechanical controlled processing（TMCP）was investigated.Processing condition of controlled cooling on a ROT in the laboratory rolling mill was discussed.The results indicated that the microstructure containing polygonal ferrite,granular bainite and a significant amount of the stable retained austenite can be obtained through three-step cooling on the ROT after hot rolling.TMCP led to ferrite grain refinement.Controlled cooling after hot rolling resulted in the stability of the remaining austenite and a satisfactory TRIP effect.Excellent mechanical properties were obtained through TMCP for the hot rolled TRIP steel.     

连续退火温度对高硅双相钢组织及性能影响

 用连续退火模拟试验机,在实验室试制了冷轧高硅DP590,并通过扫描电镜、EBSD、透射电镜和力学性能测试研究了不同退火温度（735~835℃）对其组织和力学性能的影响。结果表明：退火温度对高硅双相钢强度和塑性有重要的影响,当退火温度为785℃时,材料获得良好的综合力学性能。不同温度退火后得到的组织均为铁素体和均匀分布在其晶界上的岛状马氏体;利用EBSD技术清晰地观察到离散分布于铁素体和马氏体晶界处的残余奥氏体。运用透射电镜观察到马氏体周围的位错线及位错团,这是双相钢连续屈服特性的重要保障。     

热轧温度参数对Nb-Ti和Nb-V微合金钢力学性能的影响

 设计了650 MPa级的Nb Ti和Nb V微合金钢的化学成分。采用正交实验方法考察了加热温度、终轧温度和终冷温度对这2种钢力学性能的影响。实验结果表明,加热温度和终冷温度是影响Nb Ti和Nb V钢力学性能的主要因素。2种钢的伸长率与屈服强度以及屈强比与屈服强度之间都具有明显的相关关系。     

Effect of Rolling Process on Microstructure and Properties of 95CrMo Drill Steel

In order to improve the strength and toughness of 95CrMo steel and explore a short flow process,a direct rolling process was employed,and the effect of finishing rolling process on microstructure and mechanical properties was investigated.The results show that,with the decrease of finishing rolling temperature,inter-lamellar spacing in-creases,the strength as well as hardness has a general increase,and secondary cementite is distributed uniformly but represents a remarkable decrease in size.Based on Hall-Petch type equation,an effective relationship of yield strength and pearlite structure parameters was established.The correlation coefficients between the measured and calculated strength were more than 0.9 5 ,which indicated a high reliability of the relationship.By analyzing the indi-vidual strength contributions of pearlite structures,yield strength was found to have a more great dependence on pearlite inter-lamellar spacing than colony size.