合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—铜（3）

实验室研究了Cu含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明：在淬火冷却速度较快的情况下,随Cu含量的增加,强度增加,塑性下降;随淬火冷却速度的降低,强度下降,且Cu含量越高,强度下降的幅度越大;在淬火缓冷情况下,Cu含量对强度的影响不大;随时效后冷却速度的降低,强度增加;Cu含量控制在中下限容易满足技术条件的要求。     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—镍（4）

实验室研究了Ni含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微组织和TEM结构分析,研究结果表明：随Ni含量的增加,δ-铁素体含量减少,As点降低;在相同回火温度下,随Ni含量的提高,强度增加。随淬火冷却速度的降低,强度下降,且Ni含量越高,强度下降的幅度越小;随时效后冷却速度的降低,强度增加,且Ni含量越高,强度增加的幅度越大。Ni含量控制在中上限容易满足技术条件的要求。     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—碳(1)

实验室研究了C含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明:随C含量的增加,As点、Mf点降低,且Mf点可降到室温以下,导致强度降低,塑性、韧性增加;随淬火冷却速度的降低,强度降低,塑性增加;随时效冷却速度的降低,强度增加;选择低的C含量容易满足技术条件要求。     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—铬(2)

实验室研究了Cr含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明:随Cr含量的增加,容易产生δ铁素体,引起C、Cr等元素的偏析,使As点、Mf点降低,且Mf点可降到室温以下,导致强度降低、塑性、韧性增加;随淬火冷却速度的降低,强度降低,塑性增加;随时效冷却速度的降低,强度增加;选择下限的Cr含量容易满足技术条件要求。     

调整处理对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响

实验室研究了调整处理工艺对0cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微组织观察,结果表明：随调整处理温度的提高,强度逐渐增加,塑性、韧性逐渐下降;816℃整处理后,随时效温度的提高,强度逐渐下降,塑性、韧性逐渐增加;在相同的时效温度下,与固溶态相比,调整处理后的强度显著较低但塑性、韧性较高。     

化学成分和热处理工艺对17—4PH钢力学性能的影响

为了解决0Cr17Ni4Cu4Nb在物理性能检验时强度指标比GB／T8732标准值高的问题,研究了化学成分、热处理工艺包括固溶处理、时效处理和冷却速度对0Cr17N-4Cu4Nb的显微组织和力学性能的影响。结果表明：（1）为了提高合格率Cr含量控制下限,M控制在中上限,将δ-铁素体的含量控制在5％以下,化学成分应精确控制减小波动,特别是碳含量;N应分析和控制;（2）在GB8732—88规定的温度范围内（1020℃-1060℃）固溶处理温度对性能的影响不大;（3））冷却速度、试样固溶及第一次时效后进行下一步处理前的温度是获得良好力学性能的关键,并且前者对力学性能的影响程度要大于后者。室温在20℃左右时,冷却速度最合适,合格率最高。     

时效处理对05Crl7Ni4Cu4Nb马氏体沉淀硬化不锈钢力学性能及组织的影响

试验研究了 1040 ℃固溶的马氏体沉淀硬化不锈钢05Cr17Ni4Cu4Nb在480~620 ℃时效5 h的组织,强度和硬度。结果表明,随时效温度升高,马氏体基体逐渐分解,碳化物析岀而降低;在时效处理过程中,随时效温度升高,富Cu相最初以球形析出,逐渐发展成椭圆形及杆状,尺寸增大,与基体共格界面消失,强化效果减弱;05Cr17Ni4Cu4Nb钢经1040 °C固溶,480 °C 5h时效后,其HRC硬度值44.3,满足钢材HRC硬度值43的要求。     

固溶时效对TC19钛合金棒材组织及性能的影响

对TC19钛合金棒材进行固溶时效热处理,利用SEM及力学性能测试研究固溶温度、时效温度对其组织及室温力学性能的影响,并对不同固溶冷却方式及时效时间下的组织和力学性能差异进行对比研究。结果表明:固溶处理后棒材组织为初生α相和亚稳态β相基;再经时效处理后组织转变为分布在β相基体间的条状初生α及弥散在β相中的细小α析出相。当时效温度一定时,随固溶温度的升高,强度增加,塑性下降;当固溶温度一定时,随时效温度的升高,强度先略微升高后降低,塑性升高;固溶后冷却速度较快及延长时效处理时间时,试样均呈现强度升高,塑性下降的规律。热处理工艺为860℃/1 h,空冷+570℃/4 h,空冷时,棒材强塑性匹配最佳。     

焊接热输入对Nb-Ti钢CGHAZ组织韧性影响

为了探究Nb Ti钢合适的焊接热输入范围并指导实际焊接工艺过程，利用Formastor F Ⅱ型自动相变测量仪和Gleeble 3800热模拟试验机研究了焊接热输入对Nb Ti钢相变温度、组织和韧性的影响规律。结果发现，当冷却速度大于6 ℃/s时，Nb Ti钢模拟CGHAZ的组织为粒状贝氏体和板条贝氏体，且随着冷却速度降低，板条贝氏体含量下降，粒状贝氏体含量增加；当冷却速度为6 ℃/s时，出现晶界铁素体组织，且随着冷却速度继续下降，晶界铁素体含量增加；当冷却速度不大于0.6 ℃/s时，组织为完全的铁素体和珠光体。随t8/5时间的增加，M A含量先增加后减少，在t8/5为178 s时，M A面积百分数达到最大值，为5.1%。当t8/5时间为144～178 s时，M A组元的含量是控制Nb Ti钢模拟CGHAZ区韧性的主要因素；当t8/5为256 s时，M A组元含量下降，粗大的晶界铁素体是控制Nb Ti钢模拟CGHAZ韧性的因素。     

冷却工艺对X80HD2管线钢组织和性能的影响

试验分析了开冷温度、冷却速度和终冷温度对X80HD2管线钢组织和性能的影响,结果表明,在不同开冷温度下,均能得到铁素体和贝氏体双相组织,随开冷温度的降低,铁素体含量增多,M/A含量增加,屈服强度下降,Rt0.5/Rm下降,均匀伸长率降低;随冷却速度提高,贝氏体组织细化,屈服强度增加,Rt0.5/Rm升高,均匀伸长率降低;随终冷温度降低,M/A细化,抗拉强度降低,Rt0.5/Rm升高,加工硬化速率升高,均匀伸长率升高。最佳冷却工艺参数:开冷温度690℃,冷却速度15℃/s,终冷温度400℃。     

Improvement in Mechanical Properties of Microalloyed Steel 30MSV6 by a Precipitation Hardening Process

 The microstructural evolutions and mechanical properties of vanadium microalloyed steel (30MSV6) during precipitation hardening were studied. The effects of aging temperature and cooling rate on mechanical strength (yield strength and ultimate tensile strength) were similar. Increasing aging temperature or cooling rate firstly increased the mechanical strength of specimens up to their maximum values, which then decreased with further increase in aging temperature or cooling rate. Microstructural evolutions revealed that cooling rate had significant effects on the pearlite interlamellar spacing and size of pre-eutectoid ferrite. Unlike the effect of austenitizing temperature, the pearlite interlamellar spacing and pre-eutectoid ferrite size were decreased by increasing the cooling rate from austenitizing temperature. According to the microstructural evolutions and mechanical properties, the optimal heat treatment process of microalloyed steel 30MSV6 was austenitizing at 950 ℃ for 1 h, air cooling (3. 8 ℃/s) and aging at 600 ℃ for 1. 5 h. This optimal heat treatment process resulted in a good combination of elongation and yield strength.     

0Cr17Ni4Cu4Nb组织及力学性能试验

采取不同热处理方式观察0Cr17Ni4Cu4Nb钢的组织对力学性能的影响。该钢经固溶、时效后,析出与基体保持共格关系的富铜SH（ε—Cu）、NbC、M23C6等碳化物使强度提高,并在480℃时效时,获得最大的强度值。     

N含量对17-4PH马氏体时效不锈钢铁素体相和性能的影响

试验用17-4PH不锈钢(/%:0.02～0.03C,0.40～0.54Si,0.41～0.60Mn,0.018～0.026P,0.001S,15. 56～15. 75Cr,4. 31～4. 50Ni,3. 21～3.40Cu,0. 20～0. 25Nb,0. 013～0. 067N)采用20 t EAF+LF+VOD+ESR的工艺冶炼,锻造成Φ150 mm棒材。试验结果表明:钢中N含量由0.013%增加至0.067%时,钢中铁素体含量由0.5%增至6%,钢的强度、硬度升高,塑性降低。当N含量控制在0.020%～0.045%,钢中铁素体含量为1%～3%,经1040℃ 1h水冷+480℃  2 h空冷后,钢的力学性能合格;固溶态钢的HB硬度值≤325,优化了该材料的加工性能。     

固溶冷却介质对优质GH738合金组织及力学性能的影响

研究了不同固溶冷却介质(油、空、棉)及之后的时效处理对优质GH738 (HQGH738)合金组织及力学性能的影响.分别利用光学金相显微镜(OM)和场发射扫描电镜(FESEM)对热处理各阶段合金的晶粒组织及γ'相分布情况进行观察,同时检测热处理各阶段拉伸强度.结果表明:冷却介质对HQGH738合金晶粒尺寸无影响,而主要影响一次及二次γ'相的回溶及析出行为,进而影响合金的性能.固溶阶段,随冷速的提高(油淬＞空冷＞棉冷),合金中二次γ'相减少,尺寸越小,固溶后合金抗拉强度降低.经过稳定化处理后,3种冷却方式下合金强度顺序不变,但差值减小.再经过双时效后,三者抗拉强度相当.冷速越快,一次γ'相粗化越慢,从而在双时效过程中析出更多的细小二次γ'相,最终合金的屈服强度随冷速的增加而增强.     

Effects of micro-alloying and production process on precipitation behaviors and mechanical properties of HRB600

Effects of micro-alloying elements and production process on microstructure,mechanical properties and precipitates of 600 MPa grade rebars were studied by using pilot test,metallographic observation,tensile test,thermodynamic calculation and transmission electron microscopy. The results show that the tested steels are composed of ferrite and pearlite,in which the content range of pearlite is 33%-45%. For vanadium microalloyed steel,interphase precipitation strengthening effect of V can be promoted and the yield strength of tested steels can be increased with increasing V content and decreasing finishing rolling temperature. The temperature of terminated cooling should be more than 700 °C when the water cooling is used. When niobium is added to the steel,more coarse( Nb,V) C,N precipitates are generated at high temperature,so that the solid solubility of precipitated phases of vanadium is reduced and the precipitation strengthening effect of vanadium is weakened.     

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The influence of Nb on tensile properties at room temperature and 650?? as well as the effects of Nb on stress rupture properties at 650??/690MPa of GH4169 alloy with standard heat treatment (STD) and direct aging heat treatment (DA) were investigated. Microstructure and thermodynamic calculation were also undertaken. The results show that as Nb content increases from 5??2% to 5??4% (mass percent), the mass fraction of strengthening phases in the alloy as DA increases, and the strength also improves obviously at room temperature and 650?? while the strength decreases when Nb content reaches 5??6%. At the same solution temperature, the increase of Nb content will promote the mass fraction of ?? phase in the alloy as STD, but the effect on the mass fraction of strengthening phases is not so apparent as the DA state, and the extent of strength promotion is small. The stress rupture life of the alloy as DA improves with the increasing of Nb content, and remains nearly unchanged after Nb content reaches 5??6%. Whereas when Nb content rises to 5??6%, the change of ?? phase??s amount and morphology in the alloy as STD may result in significant decrease of the stress rupture life.