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热锻用贝氏体型调质钢具有优良的抗拉强度性能和冲击特性。但贝氏体型非调质钢的屈服强度与普通热锻用调质钢相比还不尽如人意,因此,了为提高热锻用高强高韧贝氏体型非调质钢的屈强比(σ0.2/σ B),进行了包括热处理操作在内的若干调查研究,所得结果如下:(1)通过450-600℃回火处理,提高了贝氏体型非调质钢的屈强比。(2)通过控制制冷却速度也提高了贝氏体型非调质钢的屈强比;在控制冷却速度处理过程中,锻钢通常空冷到接近贝氏体转变开始温度,然后装箱缓冷。(3)[Si]含量与残余奥氏体量有关;残余奥氏体量少时可获得较高的屈强比。由于残余奥氏体(从晶体结构观点考虑认为残余奥氏体比基体更易变形)量的降低,钢中的局部变形得到抑制。(4)残余奥氏体量与[Si]含量相关,[Si]含量较低时,残余奥氏体量少。看来会发生这种现象;由于在从奥氏体向贝氏体转变的过程中推迟碳扩散的[Si]含量少而抑制了奥氏体相的碳富集,所以奥氏体难以保持在室温。(5)因此,通过降低[Si]含量来抑制残余奥氏体量就能无需进行补热处理操作而提高屈强比,从节能和经济性角度考虑,认为这种方法是最可取的。根据上述研究结果,本公司已开发了具有更高屈强比的新的贝氏体型非调质钢,并且已将这些钢实际用作卡车转向件用材料。 相似文献
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通过对多相组织管线钢进行横向预应变模拟管线钢在制管过程中的横向扩径,进而研究横向预应变对多相组织管线钢横向和纵向拉伸应变行为的影响.发现多相组织X80管线钢在横向预应变后的加工硬化表现出明显的方向性,平行于预应变方向加工硬化高,但在低于2%预应变条件下屈强比仍能保持在0.95以下.垂直于预应变方向在预应变后仍能保持连续屈服的拉伸应变特征,具有较低的屈强比(小于0.75)以及高的均匀延伸率.此外通过对预应变后钢板进行时效处理,以此研究制管后防腐热涂覆对管线钢拉伸应变行为的影响.结果表明多相组织管线钢拥有很好的抗时效稳定性. 相似文献
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利用旋转弯曲疲劳试验方法对比研究了新开发的两种转向节用贝氏体型非调质钢的高周疲劳性能。结果表明, 两种不同碳含量的贝氏体型非调质钢具有细小均匀的贝氏体铁素体+M-A岛组成的粒状贝氏体组织;两者具有相当的强度水平和疲劳性能,但其疲劳性能低于同等强度水平的调质钢。与锻态相比,正火处理后,试验料的抗拉强度和疲劳强度均有一定程度的降低,但屈强比和疲劳极限比明显提高。对疲劳断口的分析表明,试验料的疲劳裂纹均起源于表面基体,疲劳裂纹以准解理机制扩展。裂纹扩展速率试验表明,含碳量较低的试验料的疲劳裂纹扩展速率da/dN明显低于含碳量较高的试验料。 相似文献
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石油、天然气输送管道通常服役环境较恶劣:管道压力大、输送介质复杂,管道的安全问题日显突出,对管线钢屈强比提出更高要求.屈强比较高是长期困扰CSP流程生产管线钢的难题,运用数理统计方法对生产管线钢的过程工艺参数进行对比分析,查找影响屈强比的关键因素,并通过采取有效措施:调整化学成分、过程工艺参数,提高固溶强化效果,使其屈... 相似文献
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R. Chait 《Metallurgical and Materials Transactions B》1972,3(2):369-375
Room temperature tensile and compressive true stress-true strain curves of various high strength steels (quenched and tempered
4340 steel, 410 martensitic stainless steel, and H-11 steel; and aged 300-grade 18 Ni maraging steel) were analyzed to determine
the effect of the various microstructures, on what has been termed the strength differential (SD),i.e., the strength level difference between the tensile and compressive flow curves. Care was taken to insure that the compressive
deformation was homogeneous. Regardless of the amount of plastic deformation, the quenched and tempered steels exhibited a
higher flow stress in homogeneous compressive deformation than for tensile deformation. The extent of the SD was dependent
on tempering temperature. This observation is consistent with what others have observed regarding yield strength behavior
of quenched and quenched-and-tempered steels. Despite the low carbon content, aged maraging steel also showed a greater resistance
to homogeneous compressive deformation. Metallographic examination of the maraging steel revealed the banding that is indicative
of segregation. However, homogenization had little effect on the SD despite a change in austenite grain size, reverted austenite
content, and the austenite-to-martensite transformational strains shown by Goldberg to be present in segregated material. 相似文献
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针对ML20MnTiB生产的10.9级扭剪型钢构螺栓紧固轴力标准偏差大的问题进行了试验分析,通过进行螺母的磷皂化试验和螺栓热处理试验,表明螺母表面润滑状态、螺栓热处理工艺都影响紧固轴力检验结果,但不是造成紧固轴力标准偏差大的主要原因。通过更换新的车刀,将螺栓尾部凹槽位置螺栓直径由13.9减小为13.6 mm,凹槽底部曲率半径由0.17增大为0.5 mm,使紧固轴力平均值由176降低为167 kN,同时标准偏差由17.4降低为15.5以下,解决了紧固轴力标准偏差大的问题。 相似文献
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N. N. Sereda A. K. Gerikhanov M. S. Koval'chenko V. A. Tsyban' L. G. Pedanov 《Powder Metallurgy and Metal Ceramics》1985,24(9):721-724
Conclusions The fatigue limit of the titanium carbide and tungsten carbide alloys investigated on a basis of 5·108 cycles lies in the range (20–30)·107 Pa, and is thus comparable with the endurance of type ShKh high-carbon (1% C-Mn-Si-Cr) ball-bearing steels. The strength and character of fracture of the hard metals are determined by the properties and structural state of their phase constituents. The highest strength is exhibited by tungsten carbide and titanium carbide alloys with evenly distributed equal-sized carbide grains. The character of fracture of the hard metals varies depending on their method of loading, from brittle in static loading to tough-and-brittle in cyclic loading. On time bases not exceeding 106 cycles titanium carbidehard metals are comparable in fatigue resistance to the standard tungsten-containing hard metals.Translated from Poroshkovaya Metallurgiya, No. 9(273), pp. 67–71, September, 1985. 相似文献
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