热处理对9Cr低活化马氏体钢组织和力学性能的影响

研究了热处理对9Cr低活化马氏体钢显微组织和力学性能的影响.用光学显微镜和扫描电子显微镜观察了材料的显微组织、拉伸断口和冲击断口;用X射线衍射仪检测了材料的晶体结构.结果表明:9Cr低活化马氏体钢的晶粒尺寸从950℃的6.28μm增加到1200℃的66.5μm.两种热处理工艺(950℃×30min水冷+780℃×90min空冷和1050℃×30min水冷+780℃×90min空冷)处理后的9Cr低活化马氏体钢显微组织为全马氏体.二种工艺处理后拉伸力学性能相近,但冲击性能差别明显.二者的韧脆转变温度分别为-72℃和-62℃.选择950℃×30min水冷+780℃×90min空冷的热处理工艺能够提高9Cr低活化马氏体钢的冲击韧度.     

加热规范对316LN铸态奥氏体不锈钢组织和性能的影响

研究了316LN奥氏体不锈钢在不同温度和不同保温时间下,铁素体的含量、形貌的变化规律以及对力学性能的影响.结果表明:随同溶温度的升高、固溶时间的延长,铁素体的含量逐渐减少,形貌由原来的骨骼状逐渐向比较光滑的圆点状演变,硬度有整体下降的趋势.     

Effect of Austenitizing Heat Treatment on the Microstructure and Hardness of Martensitic Stainless Steel AISI 420

The effect of austenitizing on the microstructure and hardness of two martensitic stainless steels was examined with the aim of supplying heat-treatment guidelines to the user that will ensure a martensitic structure with minimal retained austenite, evenly dispersed carbides and a hardness of between 610 and 740?HV (Vickers hardness) after quenching and tempering. The steels examined during the course of this examination conform in composition to medium-carbon AISI 420 martensitic stainless steel, except for the addition of 0.13% vanadium and 0.62% molybdenum to one of the alloys. Steel samples were austenitized at temperatures between 1000 and 1200?°C, followed by oil quenching. The as-quenched microstructures were found to range from almost fully martensitic structures to martensite with up to 35% retained austenite after quenching, with varying amounts of carbides. Optical and scanning electron microscopy was used to characterize the microstructures, and X-ray diffraction was employed to identify the carbide present in the as-quenched structures and to quantify the retained austenite contents. Hardness tests were performed to determine the effect of heat treatment on mechanical properties. As-quenched hardness values ranged from 700 to 270 HV, depending on the amount of retained austenite. Thermodynamic predictions (using the CALPHAD? model) were employed to explain these microstructures based on the solubility of the carbide particles at various austenitizing temperatures.     

热处理对多层不锈钢复合材料组织和性能的影响

研究了用累积复合轧制技术制备的8层不锈钢复合材料,经(200～900)℃×(0.5～2)h热处理后,微观组织以及力学性能的变化。结果表明:在保温时间不变的条件下,随热处理温度升高,微观组织逐步经历了回复→再结晶→晶粒长大的过程,抗拉强度和硬度下降,塑性提高,600℃以上温度变化较为显著;在温度不变的条件下,随保温时间的延长,组织和力学性能变化不是很明显。试样弯曲90°试验未见明显分层和撕裂迹象,且拉伸试样均为韧性断裂。采用600℃×1 h的热处理制度,材料的综合力学性能较佳。     

双相不锈钢在热处理过程中组织及性能的研究

采用光学显微镜、扫描电镜和电子显微镜对双相不锈钢在不同热处理温度下的显微组织、力学性能、相组织转变和耐蚀性等进行了研究。结果表明,随着热处理温度的升高,试验钢的硬度和强度不断降低,伸长率增加;适当降低Mo元素、提高Cr和C元素的质量分数和控制热处理温度可显著提高双相不锈钢力学性能和耐点蚀性能。     

机械臂用不锈钢热处理及其组织与性能研究

对比分析了原始态和经传统双相区工艺及过饱和单相区工艺处理的不锈钢机械臂的显微组织、力学性能、拉伸断口形貌和耐腐蚀性能的变化。结果表明,传统双相区工艺和过饱和单相区工艺下不锈钢的抗拉强度、断面收缩率和显微硬度均高于原始态的,经过过饱和单相区工艺处理的不锈钢机械臂强度和塑性结合较好;不锈钢机械臂的耐腐蚀性能从高至低的处理工艺依次为:单相区工艺传统双相区工艺原始态。     

热处理对模具钢组织与力学性能的影响

考察3Cr2Mo型塑料模具钢经200～600℃回火处理后的力学性能和组织形态变化.结果表明,回火处理后,该钢粒状贝氏体组织出现大量针状碳化物和稳定化的不连续条形岛状组成物,发现其有利于提高3Cr2Mo钢的冲击韧度和屈服强度.当在350℃同火处理3 h,可使该钢的屈服强度提高40%,冲击韧度提高60%.     

热处理工艺对CrNiMoBNb16-16耐热螺栓钢组织和力学性能的影响

从热处理工艺对室温、高温拉伸性能的影响和试验温度对拉伸性能的影响两个方面分析了CrNiMoBNb16-16钢组织和力学性能之间的关系。试验结果表明，随着试验温度（20～650℃）的提高，强度下降比较明显，而塑性有所下降。对于此实验钢，温锻要比高温锻造时的综合性能好。经金相分析，其性能的变化与其化学成分中的铌有着密切的联系。     

Rapid Tempering of Martensitic Stainless Steel AISI420: Microstructure,Mechanical and Corrosion Properties

In this research, the effect of rapid tempering on the microstructure, mechanical properties and corrosion resistance of AISI 420 martensitic stainless steel has been investigated. At first, all test specimens were austenitized at 1050 °C for 1 h and tempered at 200 °C for 1 h. Then, the samples were rapidly reheated by a salt bath furnace in a temperature range from 300 to 1050 °C for 2 min and cooled in air. The tensile tests, impact, hardness and electrochemical corrosion were carried out on the reheated samples. Scanning electron microscopy was used to study the microstructure and fracture surface. To investigate carbides, transmission electron microscopy and also scanning electron microscopy were used. X-ray diffraction was used for determination of the retained austenite. The results showed that the minimum properties such as the tensile strength, impact energy, hardness and corrosion resistance were obtained at reheating temperature of 700 °C. Semi-continuous carbides in the grain boundaries were seen in this temperature. Secondary hardening phenomenon was occurred at reheating temperature of 500 °C.     

Effect of Spheroidizing Annealing on Microstructure and Mechanical Properties of High-Carbon Martensitic Stainless Steel 8Cr13MoV

The effects of holding time during both austenitizing and spheroidizing on microstructure and mechanical properties of high-carbon martensitic stainless steel 8Cr13MoV were experimentally studied. The results showed that the amount of carbides and the proportion of fine carbides decrease first and then increase with the increase in austenitizing time (t ₁) in the case of short spheroidizing time (t ₂), whereas the amount of the lamellar carbides increases. In the case of long t ₂, both the amount of carbides and the proportion of fine carbides decrease, and the amount of the lamellar carbides did not increase. The hardness of the steel decreases first and then increases with the increase of t ₁. Under the conditions of different t ₁, the change in the size of carbides and hardness of the steel show a same trend with the variation of t ₂. The size of spheroidized carbides increases, whereas the hardness of the steel decreases with increasing t ₂. The longer the holding time of austenitizing, the higher is the spheroidizing rate at the earlier stage. However, the spheroidizing rate shows an opposite trend with t ₁ at the later stage of spheroidizing. The effect of cooling rate on microstructure is similar with t ₂. With increasing cooling rate, the dimension of carbides became smaller, and the amount of lamellar carbides increased. The elongation of the sample fracture exhibits no corresponding relationship with holding time, whereas it is closely related to the precipitation of secondary carbides caused by the alloying elements segregation.     

Effect of Post-weld Heat Treatment on the Mechanical Properties of Supermartensitic Stainless Steel Deposit

Supermartensitic stainless steels have good weldability and adequate tensile property, toughness and corrosion resistance. They have been developed as an alternative technology, mainly for oil and gas industries. The final properties of a supermartensitic stainless steel deposit depend on its chemical composition and microstructure: martensite, tempered martensite, ferrite, retained austenite and carbides and/or nitrides. In these steels, the post-weld heat treatments (PWHTs) are usually double tempering ones, to ensure both complete tempering of martensite and high austenite content, to increase toughness and decrease hardness. The aim of this work was to study the effect of post-weld heat treatments (solution treatment with single and double tempering) on the mechanical properties of a supermartensitic stainless steel deposit. An all-weld metal test coupon was welded according to standard ANSI/AWS A5.22-95 using a GMAW supermartensitic stainless steel metal cored wire, under gas shielding. PWHTs were carried out varying the temperature of the first tempering treatment with and without a second tempering one, after solution treatment. All-weld metal chemical composition analysis, metallurgical characterization, hardness and tensile property measurements and Charpy-V tests were carried out. There are several factors which can be affected by the PWHTs, among them austenite content is a significant one. Different austenite contents (0-42%) were found. Microhardness, tensile property and toughness were affected with up to 15% of austenite content, by martensite tempering and carbide precipitation. The second tempering treatment seemed not to have had an important effect on the mechanical properties measured in this work.     

热处理对超高碳钢组织和性能的影响

采用几种不同的热处理工艺对超高碳钢进行球化处理,并对不同热处理状态下的试样进行了组织观察和力学性能测试分析,探讨了热处理对超高碳钢组织和性能的影响。结果表明,随着碳化物球化率的提高,钢的塑性得到明显改善。经840℃×20min淬火+650℃×3h高温回火处理样品因能获得圆整度高的球状碳化物,而拥有σs=576MPa、σb=835MPa的高强度和δ5=18·4%的良好塑性。经1200℃×4h高温正火+800℃×2h球化退火处理的超高碳钢由于获得的球状碳化物颗粒细小且分布均匀,基体在变形时受到的阻碍作用较弱,故强度较高(σs=622MPa,σb=927MPa),但塑性稍有下降(δ5=16·0%)。经720℃×3·5h退火处理和840℃×20min空冷+720℃×2·5h退火处理的超高碳钢尽管含有一定量的片状碳化物,也能获得高的强度(σs>590MPa,σb>870MPa)和较好的塑性(δ>11%)。     

热处理工艺对316L不锈钢微丝组织和性能的影响

分别对 316L不锈钢微丝拉拔过程中的几道丝材进行了退火处理 ,研究了退火温度与保温时间对不同压缩率丝材的显微组织与力学性能的影响。结果表明 ,再结晶后的显微组织为完全奥氏体组织。丝径为0 2 4 5mm(压缩率为 83% )与0 113mm(压缩率为 96 % )的丝材 ,采用 10 5 0℃× 10s的热处理工艺 ,其再结晶后的晶粒度可达 11级 ,并具有优良的力学性能。丝径为0 0 3mm微丝的最佳退火工艺为 10 5 0℃× 1s。     

热处理对挤压铸造n-SiC_p/AZ91D镁基复合材料组织和力学性能的影响

采用金相、X射线衍射、扫描电镜(SEM)、拉伸试验等方法分析和测试了挤压铸造纳米Si C颗粒增强AZ91D镁基复合材料在铸态(F)、固溶态(T4)和人工时效态(T6)下的组织和力学性能。结果表明,固溶处理可使n-Si Cp/AZ91D铸态组织中的β-Mg17Al12共晶相溶入到基体中,形成单一的过饱和α-Mg固溶体,合金抗拉强度和伸长率均有大幅提高,分别达到265 MPa和13.7%;经时效处理后,复合材料的抗拉强度和屈服强度进一步提高,分别为275,145 MPa;SEM结果显示,β-Mg17Al12相主要以连续析出/非连续析出方式分别在晶内及晶界上析出,特别是纳米Si C颗粒分布对二次析出相β-Mg17Al12的形貌、尺寸、分布有一定的影响,使二次析出相变得细小和弥散分布,从而充分发挥了二次析出相的沉淀强化作用;最后对n-Si Cp/AZ91D复合材料不同热处理条件下的断口形貌进行了SEM观察,并且对其断裂方式进行了分析和讨论。     

Effect of Heat Treatment on Microstructure and Mechanical Properties of Quenching and Partitioning Steel

In order to investigate the effect of microstructural characterization on the mechanical properties and retained austenite stability, a different type of quenching and partitioning steel(I-QP) through intercritical annealing before the quenching and partitioning process was designed, which can realize lamellar intercritical microstructure compared to the conventional quenching and partitioning(QP) process. The morphology of ferrite and martensite/retained austenite is lamellar in the I-QP steel while it is equiaxed after being heat-treated by conventional QP process. The I-QP steel is proved to have better formability and mechanical properties than conventional QP steel, which is due to the highervolume fraction of retained austenite in the I-QP steel and confirmed by electron backscattering diffraction patterns and X-ray diffraction. Furthermore, the stability of retained austenite in I-QP steel is also higher than that in conventional QP steel, which is investigated by tensile tests and differential scanning calorimetry.     

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 利用拉伸、金相显微镜和扫描电镜等方法研究了不同热处理制度对奥氏体不锈钢022Cr17Ni12Mo2材料组织与力学性能的影响。结果表明：随着加热温度由950 ℃升高到1 250 ℃,材料022Cr17Ni12Mo2的晶粒越来越粗大,α相含量呈先降后升的趋势,在1 150 ℃达到最低点1.60%;试验材料的抗拉强度Rm、规定非比例强度Rp02和Rp10均发生了不同程度的下降,塑性明显提高。冷却方式对试验材料的晶粒大小、抗拉强度和伸长率几乎没有影响,但与空冷方式相比,采用水冷方式有利于组织中α相含量的降低,规定非比例强度Rp02和Rp10均提高了30 MPa到40 MPa。     

不同热处理温度对30MnSi钢组织及性能的影响

研究了淬火温度、回火温度、回火冷却介质对抗震30MnSi钢力学性能和微观组织的影响。结果表明,当淬火温度为910℃、回火温度为480℃、淬火水温为30℃时,试验钢筋具有最好的力学性能。     

热处理工艺对Nb-Ti低合金钢力学性能及组织的影响

以Nb-Ti低合金钢为研究对象,实验分析了3种不同的热处理工艺对奥氏体晶粒形态演化,以及材料微观组织和力学性能的影响,并分析了其影响机理。为低碳低合金钢的成分及热处理工艺优化提供了参考。     

热处理工艺对H13钢组织和力学性能的影响

比较了H13钢盐浴分级淬火、盐浴分级淬火＋200℃×2h回火、真空高压气淬和真空高压气淬＋200℃×2h回火后的力学性能,试验表明,H13钢真空高压气淬后的力学性能更为优良。这主要是因为H13钢盐浴分级淬火后,存在拉应力,而真空高压气淬后存在压应力;同时还与真空淬火具有脱气作用,残留奥氏体较多等因素有关。研究结果还表明分级淬火后应快速冷却,减少贝氏体量,增加马氏体转变量,抵消部分热应力,有利于减小模具的畸变和提高韧性。