热处理对高强度微合金钢组织与性能的影响

研究了不同热处理工艺对所设计的高强度微合金钢(屈服强度大于500 MPa)的组织与性能的影响.结果表明,通过适当的热处理工艺可以获得由多边形铁素体加一定含量针状铁素体的双相组织,既能显著提高钢的强度,还能保持较低的屈强比.     

Mg-Ti复合脱氧对低碳微合金钢组织性能的影响

通过焊接热模拟和冲击韧性试验,研究了Mg-Ti脱氧和Al脱氧在大线能量焊接热循环条件下对低碳微合金钢粗晶区组织性能的影响。结果表明,Mg-Ti脱氧钢粗晶区的组织主要是针状铁素体（AF）和少量的多边形铁素体,Al脱氧钢粗晶区的组织主要是低碳贝氏体＋大量的块状铁素体。对Mg-Ti脱氧钢和Al脱氧钢在不同焊接热循环下的冲击韧性进行研究,结果表明随着焊接热输入量的增大,两种脱氧钢的冲击韧性都有所下降,但是从总体上来说Mg-Ti脱氧钢粗晶区的冲击韧性远远高出Al脱氧钢粗晶区的冲击韧性。     

热处理工艺对40Cr组织和性能的影响

研究40Cr钢在不同热处理工艺下的组织和耐磨性.结果表明:40Cr最佳的热处理工艺为经850 ℃保温60 min正火,试样硬度约为200 HBS,正火后组织为索氏体;再经780 ℃淬火保温30 min后水冷,试样硬度约为52 HRC,淬火所得组织为板条状马氏体和针状马氏体;最后经200 ℃低温回火后,试样硬度维持在50 HRC以上,所得组织为回火马氏体;经淬火及回火后,试样耐磨性得到显著提高.     

NR360耐磨钢板手工电弧焊接头的组织与性能

研究了高强度耐磨钢板NR360的焊接接头组织和力学性能,结果表明,焊缝组织主要为块状或针状铁素体,热影响区组织分布比较均匀,主要为细小板条贝氏体与少量马氏体,熔合区结合良好。热影响区和NR360钢板本体硬度相近。NR360耐磨钢板焊接接头具有良好的强韧性。     

合金元素Mo对冷轧双相钢组织的影响

分析Mo微合金冷轧双相钢和普通C-Mn冷轧双相钢在不同双相热处理工艺下微观结构,讨论Mo对冷轧双相钢组织变化规律的影响。实验结果表明：当两种双相钢以1700℃／s冷却时,均获得了铁素体、马氏体双相组织,马氏体均匀分布在铁素体基体上,随着加热温度的升高,普通C-Mn双相钢得到的马氏体体积分数多。当以5．4℃／s冷却时,Mo微合金双相钢得到的马氏体体积分数多;当加热到820℃保温结束后以5．4℃／s的速率冷却时,普通C-Mn钢的组织组成相为铁素体、珠光体、马氏体;Mo微合金钢的组织组成相为铁素体、贝氏体、马氏体;Mo对铁素体晶粒的细化作用不明显。     

NR360贝氏体耐磨钢板的组织与性能

研究南钢NR360贝氏体耐磨钢板的组织、力学性能、耐磨性能及焊接性能。结果表明,NR360耐磨钢板的组织为板条状的无碳化物贝氏体及残余奥氏体组织,该钢板具有较高的屈服强度、抗拉强度,及良好的韧性。钢板的耐磨性好,在滑动磨损试验下,钢板的磨损机制主要为微切削与犁沟机制。焊接接头中焊缝组织主要为块状和针状铁素体组织,热影响区组织为细化的板条贝氏体与马氏体组织。焊接接头具有良好的强韧性,热影响区的硬度与耐磨钢基体相近。     

CLAM/15-15Ti异种钢TIG焊接头热处理前后组织演变

为探究马氏体钢与不锈钢焊接接头的组织演变及硬度特征,采用钨极氩弧焊对中国低活化马氏体(CLAM)钢和15-15Ti不锈钢进行焊接。接头热处理前后的显微组织和硬度进行对比。结果表明,焊态焊缝由板条马氏体+少量δ铁素体组成,硬度在407 HV～463 HV之间。CLAM钢热影响区分为完全淬火去和不完全淬火区,不完全淬火区有明显的软化现象,15-15Ti不锈钢热影响区是整个接头硬度最低的区域。热处理后,接头高硬度区减小,焊缝组织转变为回火马氏体,析出物增多,硬度相比焊态下降了约20%。     

淬火温度对X80管线钢组织影响分析

采用双相区加速冷却法(DPAC),X80管线钢经奥氏体化及缓冷后分别在760、740、720、700、680℃淬火。淬火组织分别经4%硝酸酒精与LePera试剂进行金相腐蚀,分别进行组织定性/定量分析及整体/组织硬度测试。结果表明,不同淬火温度下组织为多边形铁素体+针状铁素体+贝氏体/马氏体复相组织。与硝酸酒精腐蚀的微观结构相比,LePera试剂可清晰显示马氏体/奥氏体组织,但铁素体晶界模糊。随淬火温度下降,铁素体晶粒尺寸与含量增加;针状铁素体逐渐向贝氏体/马氏体复相组织转化;马氏体/奥氏体岛状组织分布上由铁素体/贝氏体两相晶界间向铁素体同相晶界间转变,组织形态上由薄膜状向颗粒状转变。     

Nb对低碳微合金钢相变的影响

采用Gleeble-1500D型热模拟机测定了不同含铌量低碳微合金钢在不同冷却速度下,过冷奥氏体连续冷却相变点,分析观察了显微组织,测定了其显微硬度.得出:在同一冷却速度下,随着含铌量的提高,过冷奥氏体连续冷却相变点降低,容易出现条片状贝氏体铁素体,显微硬度提高;在相同成分下,随着冷却速度的增加,含铌钢中铁素体越来越细小,由等轴状大块铁素体组织向条片状贝氏体铁素体转变.     

P80高级塑料模具钢热处理生产工艺的试验研究

对比研究淬火回火工艺及正火回火工艺对P80沉淀硬化塑料模具试验钢组织及硬度的影响。结果表明:20 mm方块试样淬火后得到马氏体组织,正火后得到马氏体与少量贝氏体组织;随着回火温度的提高,硬度先升高后降低,500℃回火时硬度最高,但淬火回火试样的最高硬度(45 HRC)高于正火回火试样(42 HRC);100 mm方块试样在淬火加500℃回火后主要是板条回火马氏体组织,硬度范围为42~45 HRC,平均硬度为44 HRC;正火加500℃回火后主要是板条贝氏体组织,硬度范围为39~43 HRC,平均硬度为41 HRC。实际生产中采用热轧控冷加回火工艺生产P80的厚钢板能够满足用户的硬度要求。     

Study on M／A islands in pipeline steel X70

The free structure of M/A islands in pipeline steel X70 has been studied by transmission electron microscope (TEM). It is shown that the M/A islands are about 1-2 μm in size and distribute at the grain boundary of irregular massive ferrite or acicular ferrite in the microstructure of the steel undergoing TMCP (thermo-mechanical controlled processing). The analysis of diffraction contrast shows that the M/A islands consist of retained austenite and some martensite lamellae different in size and orientation. The microtwinning and midrib exist in the lamella of lenticular martensite, which exhibit the typical character of high-carbon martensite. The influences of TMCP parameters on M/A islands have been studied carefully. With the increase of the cooling speed, the amount of M/A islands decrease slightly and the morphology of M/A islands changes to thin dispersive short bars from thick irregular long strips.     

10Ni5CrMoV钢厚板MIG焊接接头组织研究

用光学显微镜和电子显微镜对10Ni5CrMoV船用钢厚板的MIG焊接接头进行了组织分析和断口分析，用能谱分析仪（EDS）对焊缝及熔合线处的氧化物作了定点谱成分析，根据组织分析和氧化物成分分析结构对针状铁素体的形成及韧化机理进行了探讨，研究结果表明：焊缝组织为针状铁素体 氧化物 少量板条马氏体，熔合线附近组织为板条马氏体针状铁素体 氧化物，粗晶区组织为板条马氏体；焊缝及熔合线附近的氧化物是针状铁素体的形核剂，针状铁素体可以在一个氧化物上实现多维形核，大量的针状铁素体组织是焊缝及熔合线具有很好的低温韧性的重要原因。     

Toughening mechanisms of a high-strength acicular ferrite steel heavy plate

An ultra-low carbon acicular ferrite steel heavy plate was obtained with an advanced thermo-mechanical control process-relaxed precipitation controlled transformation (TMCP-RPC) at Xiangtan Steel, Valin Group. The heavy plate has a tensile strength of approximately 600 MPa with a lower yield ratio. The impact toughness of the heavy plate achieves 280 J at ?40°C. The fine-grained mixed microstructures of the heavy plate mainly consist of acicular ferrite, granular bainite, and polygonal ferrite. The high str...     

Nb变质处理铸造高速钢的组织和性能

在铸造高速钢刀具中添加质量分数为4％的Nb形成孤立粒状碳化物以细化铸态组织,研究了不同固溶温度和回火温度下的组织和硬度.结果显示:固溶处理温度为1 200℃时,碳化物呈孤立粒状均匀分布;低于此温度,晶界上的羽毛状碳化物未能完全溶解,而高于此温度则导致粒状NbC的溶解.回火温度为570℃到580℃时,可获得细针状马氏体和最少量的残余奥氏体;低于此温度,针状马氏体粗大,残余奥氏体量较多.     

Mechanical properties of fine-grained dual phase low-carbon steels based on dynamic transformation

The fine grained dual phase (FG-DP) steel with ferrite grains of 2-4.5 μm and martensite islands smaller than 3 μm was obtained through the mechanism of deformation-enhanced ferrite transformation (DEFT). Mechanical properties of the steel were tested at room temperature. The results indicated that with a similar volume fraction of martensite (about 20vol%),FG-DP steel ex-hibited a superior combination of higher strength and more rapid strain hardening at low strains compared with the coarse-grained dual ph...     

X80管线钢的应变硬化特性分析

采用准静态拉伸和扫描电镜分析了热轧X80管线钢的应变硬化行为及其微观组织结构。结果表明,X80管线钢的应变硬化特性决定均匀伸长率大小,针状铁素体+M/A的微观组织结构使得应变硬化指数呈现平台、缓慢下降和迅速下降三个变化阶段。     

Microstructure effect on nanohardness distribution for medium-carbon martensitic steel

Many studies have been focused on the Fe-C based martensitic steels during the past several decades due to its importance as a high-strength material used for construction components and automobile parts[1―8]. The macroscopic mechanical property of the multi-phase material originates from the mechanical properties of each phase and their distribution and interaction. Some of the mechanical properties such as fatigue are asso-ciated with the local strength as crack initiation and propagation s…     

马钢2号高炉中修后开炉达产操作实践

对马钢2号高炉中修后开炉达产操作实践进行了总结。通过制定科学的开炉方案,快速提高煤比、降低焦比,实现了顺利开炉、快速达产达效的目标。     

Influences of microstructure and texture on crack propagation path of X70 acicular ferrite pipeline steel

The aspects of two pipeline steels with different technologies were investigated by using transmission electron microscopy (TEM) and electron back-scattered diffraction (EBSD).The microstructure presents a typical acicular ferrite characteristic with free particles of martensite/austenite (M/A) constituent,which distributes in grains and at grain boundaries.The bulk textures of the pipeline steel plate are {112}<110> and <111> fibers,respectively,and the {112} <110> component is the favorable texture benefiting for drop weight tear test.Moreover,low angle boundaries and low coincidence site lattice boundaries are inactive and more resistant to fracture than high energy random boundaries.