冷轧压下率对TRIP钢组织与力学性能的影响

研究了含铝TRIP钢在相同的热处理条件和不同冷轧压下率时的组织和力学性能。结果表明,随着冷轧压下率增加,材料组织细化,屈服强度连续升高;而抗拉强度和伸长率则由于晶粒细化以及TRIP效应,先升高后降低。冷轧压下率74%时材料的综合性能最佳,此时带状组织的危害也有所减轻或消失。     

奥氏体组织对低碳中锰钢冷弯性能的影响

采用冷弯直径0～60 mm,弯曲角度180°,研究了20 mm厚度低碳中锰钢的冷弯性能,冷弯后外表均无可见裂纹,判定合格。利用光学显微镜、扫描电镜、透射电镜、电子背散射衍射(EBSD)、X射线衍射仪等手段分析了显微组织,尤其是奥氏体组织在冷弯过程中对冷弯性能的影响。结果表明,冷弯前显微组织由板条马氏体和奥氏体组成,其中原始奥氏体晶界明显;冷弯直径为0 mm变形后,样品弧顶部分奥氏体的体积分数由12.3%降至1.1%,维氏硬度由295HV1增至364HV1,晶粒尺寸由4.07μm增至4.30μm。主要原因是在冷弯过程在中奥氏体组织发生塑性变形,奥氏体晶界变形消失,沿冷弯方向呈拉伸带状组织形貌,冷弯形变时奥氏体发生TRIP效应显著。     

二次冷轧压下率对镀锡板组织和性能的影响

 为了开发二次冷轧镀锡板,采用硬度计、拉伸试验机、光学显微镜、透射电镜和X射线衍射仪研究了二次冷轧压下率对镀锡板组织和性能的影响规律。结果表明,随着二次冷轧压下率提高,试验钢的硬度和强度提高,各向异性增加,伸长率降低,当二次冷轧压下率为20%时可获得较高的硬度和伸长率的匹配。同时二次冷轧压下率对织构影响明显,当压下率为20%～40%时,α取向线中最高取向密度出现在{223}〈110〉～{445}〈110〉之间,可达到6.2,并且随变形量增加,γ取向线中{111}〈110〉取向密度逐渐从3.1降低到2.7,{111}〈112〉取向密度逐渐从4.9提高到5.3。     

二次冷轧压下率对镀锡板组织性能的影响

 为了开发高硬度二次冷轧镀锡板,采用硬度计、拉伸试验机、光学显微镜和X射线衍射仪研究了二次冷轧压下率对氮强化镀锡板组织性能的影响规律。结果表明,随着二次冷轧压下率提高,试验钢的硬度和强度提高,各向异性增加,伸长率降低,当二次冷轧压下率为44%时可达到DR-9M的技术要求。同时采用高碳和氮强化成分体系配合低温退火不利于有利织构{111}的形成,织构取向密度的峰值出现在{001}<110>~{114}<110>、{223}<110>~{445}<110>和{554}<225>,冲压成形时易在45°方向上产生制耳。     

On cells and microbands formed in an interstitial-free steel during cold rolling at low to medium reductions

The cold-rolled microstructure formed in an interstitial-free (IF) steel from low to medium reductions has been investigated by using transmission electron microscopy. Dislocation cells formed early in the process and reduced in size until a critical strain was reached, beyond which they remained at a constant size of ∼ 1-μm diameter. The critical strain coincided with the formation of microbands, and it is proposed here that microbands carry all the deformation from their creation, rendering cell refinement unnecessary. Furthermore, since the dislocation densities of meshes and cells are almost identical and the stored elastic energy E _cell is always less than E _mesh, it is proposed that cells are derived from the dislocation mesh structure. Microbands grow quickly to a length that is limited by grain boundaries. The thermodynamic condition favoring microband formation is (∂E _MB/∂ρ) < (∂E _Cell/∂ρ), and the microbands are not derived from cell structures but from dislocation sheets or walls on which deformation is concentrated.     

大压下率冷轧无取向硅钢织构演变及性能

组织和织构是影响无取向硅钢性能的重要因素。为改善产品性能,研究了冷轧压下率(71.7%~87.0%)对高牌号无取向硅钢组织、织构、磁性能和力学性能的影响。结果表明,随冷轧压下率的增加,退火晶粒平均尺寸先减小后增大;高斯和立方织构强度减弱,γ纤维织构增强,α纤维织构转变为较强的α*({ h, 1, 1}〈1/h, 1, 2〉)织构,并随冷轧压下率的增加而增强,同时其峰值逐渐向{111}面移动;工频铁损P1.5/50、高频铁损P1.0/400和磁极化强度J5000同时降低,屈服强度变化不大,表面硬度逐渐增加。当冷轧压下率由84.7%增至87.0%、厚度减至0.30 mm时,高频铁损降幅是工频铁损的11倍,表面硬度增幅变大。以上研究成果对硅钢减薄后织构及组织的优化提供了很好的指导。     

取向硅钢表面涂层结构对其性能的影响

通过扫描电镜观察取向硅钢截面涂层结构,分析其对取向硅钢绝缘性能、附着性、铁损的影响。研究结果表明:取向硅钢底层的钉扎、硅酸镁涂层、磷酸盐涂层共同作用影响着取向硅钢的性能;取向硅钢底层质量差会导致其绝缘性能和磁性能差;底层钉扎对铁损影响较大,钉扎厚度为3μm时,取向硅钢的铁损低且附着性好;硅酸镁涂层越致密均匀,取向硅钢的附着性越优良;钢板的底层厚度与磷酸盐涂层厚度同时影响着取向硅钢的绝缘性能,在相同的底层厚度下,提高磷酸盐涂层的厚度有利于提高钢板的层间电阻。     

Effect of cold rolling on the structure and mechanical properties of austenitic corrosion-resistant 10Kh18N8D3BR steel

The effect of section rolling of austenitic corrosion-resistant 10Kh18N8D3BR steel at room temperature on its structure and mechanical properties is studied. During section rolling, the steel acquires a lamellar-type structure consisting of α′-martensite lamellas and retained austenite, and the fraction of α′ martensite increases to 70% at a true strain ? ≈ 4. In the initial state, the yield strength of the steel is 285MPa and the relative elongation is 60%. Cold plastic deformation to ? ≈ 0.4 increases the yield strength to 1010 MPa. Further deformation is accompanied by higher hardening of the steel: the yield strength increases to 2050 MPa at ? ≈ 4, and the relative elongation decreases to 2%.     

退火工艺对780 MPa冷轧多相钢组织及性能影响

为了研究退火工艺对780 MPa冷轧多相钢组织及性能影响,采用万能试验机、场发射扫描电镜(SEM)、综合成形试验机及电子探针(EPMA)对两种具有相同成分、抗拉强度均为780 MPa但具有不同屈强比和扩孔性能的多相钢进行了相关研究,结果表明热处理工艺对试验钢组织、力学性能及扩孔性能有着重要影响,采用两相区退火时马氏体岛...     

冷轧变形率对冷轧轧机生产的影响

对于具有多套冷轧轧机和多品种规格的制造基地而言,各品种变形率设计的合理性对机组的生产影响很大,如何评价冷轧变形率的合理性是其中的关键。在确保质量和生产成本不增加的前提下,以轧制理论为基础,利用轧制速度分析和评价冷轧的轧制稳定性,并建立轧制速度评价模型。通过模型计算,得到变形率的最佳设计规范,并以此规范来整合优化冷轧轧机的变形率设计,实现冷轧轧机的最优化生产。优化思路和评价方法已经成功地应用在宝钢冷轧轧机变形率优化工作中,取得了良好的效果。     

冷轧压下率对无抑制剂取向硅钢初次再结晶退火的影响

对无抑制剂取向硅钢不同压下率下初次再结晶退火后的显微组织、宏观织构和微观织构进行了研究.结果表明,冷轧板织构主要为α取向线{001}＜110＞、{112}＜110＞和{111}＜110＞织构以及γ取向线{111}＜110＞织构.初次再结晶退火后,α取向线织构减弱,织构主要为γ取向线{111}＜112＞织构.随冷轧压下率的增加,冷轧和初次再结晶织构强度增加.当压下率为88％时,初次再结晶退火后 Goss 织构和{111}＜112＞织构强度最高,最有利于发生二次再结晶.EBSD 分析显示,Goss 取向晶粒大多与{111}＜112＞取向晶粒相邻.提高冷轧压下率,Goss取向晶粒和{111}＜112＞取向晶粒都增加,Goss 取向晶粒偏离理想取向角度减少.     

Effect of thermomechanical treatment conditions on the structure and properties of low-carbon weldable steel

A correlation is found between the structure and mechanical properties of rolled steel X90 sheets produced by various schemes of thermomechanical hardening: quenching from the rolling temperature followed by high-temperature tempering and two-stage thermomechanical treatment (TMT). Two-stage TMT is shown to have substantial advantages over quenching from the rolling temperature, which is related to the formation of a highly dispersed subgrain bainite structure.     

正火工艺对非调质钢48MnV组织性能的影响

非调质钢锻件,由于其钢种特性及生产过程不稳定,常造成零件性能偏差,而通过正火可以有效改变非调质钢强韧性匹配及组织形貌,扩大其适用范围。研究表明：在850~1150℃进行正火后,随着正火温度的升高,非调质钢48MnV钢材的强度升高,塑、韧性下降,显微组织晶粒尺寸增大。1050℃以上正火时,钢材显微组织粗化明显。采用950℃正火,48MnV非调质钢可以得到最佳的强韧性匹配及细小均匀的显微组织。     

High-porous materials made from alloy steel fibers: Production, structure, and mechanical properties

New high-porous corrosion-resistant materials are produced from steel fibers and a base porous material made by pressing and sintering of St.10 steel fibers. The materials obtained by chromizing (4.8–7.1 wt.%) and nickelizing (2.1–2.4 wt.%) a 60–90%-porosity base material have yield strength higher by a factor of 2 to 6 than that of the base material. The materials obtained by electrochemical coating of a base fibrous material with eutectic composite Ni-Ni₃B and subsequent liquid-phase sintering at 1120 °C contain 3.5–14.0 wt.% Ni. The yield strength of these materials at a porosity of 60–90% is higher by a factor of 2 to 3 than that of the base material.     

二次带状组织对低合金非调质钢疲劳性能的影响

采用应力比为0.1的轴向拉伸疲劳试验分别研究了低合金钢DG20Mn和35CrMo钢的疲劳性能与带状组织的关系.结果表明:带状组织对试验材料的轴向拉伸性能没有明显影响,对35CrMo钢的轴向拉伸疲劳性能影响较小,但严重减弱DG20Mn钢的轴向疲劳性能.带状组织对疲劳性能的影响主要是由于在高的疲劳拉应力下,带状组织引发疲劳微裂纹、微空洞等疲劳损伤,导致疲劳裂纹萌生及扩展模式发生变化,从而影响疲劳性能.