The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The ef...The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on EC behavior of 17 4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E C test were observed by using scanning electron microscope （SEM）. The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610℃, the hardness reached the highest value near the temperature 460℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows： pure erosion （wear） was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed e-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.展开更多
The investigation on lath martensitic transfor- mation has been carried out for 24SiMnNi2CrMoA steel using transmission electron microscopy (TEM) and X-ray diffraction.The austenite and martensite in the alloy adopt t...The investigation on lath martensitic transfor- mation has been carried out for 24SiMnNi2CrMoA steel using transmission electron microscopy (TEM) and X-ray diffraction.The austenite and martensite in the alloy adopt the intermediate orientation relationship between Kurdjumov-Sachs and Nishiyama.The adjacent laths in a packet are small-angle related or twin-related.The retained austenites which accommodate shape deformation of martensites appear commonly between adjacent laths.High Si content increases the volume fraction of retained austenites and its stability.The excellent combination of high strength and toughness of this steel is attributed to its fine martensite laths mingled with more than 5% continuous retained austenite films.展开更多
汽车行业的迅速发展使得能源消耗、环境污染等问题日益严重,而开发高强度且轻量化的汽车用钢对节能减排具有重要意义。目前正在研发的第三代先进高强钢包括轻质(Lightweight)钢、Q&P(Quenching and partitioning)钢和中锰钢(Mn质量...汽车行业的迅速发展使得能源消耗、环境污染等问题日益严重,而开发高强度且轻量化的汽车用钢对节能减排具有重要意义。目前正在研发的第三代先进高强钢包括轻质(Lightweight)钢、Q&P(Quenching and partitioning)钢和中锰钢(Mn质量分数为5%~10%)。其中,Fe-Mn-Al-C系低密度高强钢由于Al元素的加入,在密度降低的同时保持着良好的力学性能,满足第三代汽车用钢对轻量化的要求。同时,由于大量Al、Mn和C元素的添加,Fe-Mn-Al-C系低密度钢的冶炼连铸、微观结构、变形机制、加工过程及应用性能与传统钢种大不相同。本文系统阐述了Fe-Mn-Al-C系低密度钢的成分设计及其中合金元素的作用,介绍了低密度钢的微观组织结构特征;重点讨论了单一铁素体钢、奥氏体基钢、奥氏体基双相钢和铁素体基双相钢的各种强韧化机制,包括固溶强化、细晶强化、沉淀强化及其独特的应变硬化机制,如相变诱导塑性(TRIP)、孪晶诱导塑性(TWIP)、微带诱导塑性(MBIP)、剪切带诱导塑性(SIP)和动态滑移带细化(DSBR)等;并就层错能(SFE)对奥氏体钢变形机制产生的影响进行了总结;最后,对Fe-Mn-Al-C系低密度钢的强韧化机制研究进行展望,为后续研究者的工作提供参考。展开更多
The Stainless steel ring(SSR),VCu200 and TCu220C were ic randomized comparison for eight years in a cohort of 4,490 subjects covering 16 centres in 9 provinces andmunicipalities.The follow-up rate at the end of the ei...The Stainless steel ring(SSR),VCu200 and TCu220C were ic randomized comparison for eight years in a cohort of 4,490 subjects covering 16 centres in 9 provinces andmunicipalities.The follow-up rate at the end of the eithth year was 90.33%.The cumulative continuation rates were 47.06 per 100 women at the end of foe eighth year for SSR,54.05 for VCu200 and 61.14 for TCu220C.The cumulative pregnancy rates for VCu200and TCu220C were 10.35 and 8.94 per 100 women respectively,significantly lower than24.14 for SSR. There were significant differences in eight-year expulsion rates amongSSR(21.69%),VCu200(13.05%)and TCu220C(7.48%).The removal for bleedingand/or pain was the lowest in SSR;and no signaificant differences were found betweenVCu200 and TCu200C.but foe rate ws getting higher in VCu200 at the end of the eighthyear than in TCu220C.The discontinued use of IUD for desire to become pregnant in rural area was extremely higher than in urban area. The risk of pregnancy and expulsionwas in association with the types of IUD in this study,age at insertion,previous use ofIUD and pregnancy frequency prior to insertion. The risk of pregnancy and expulsion forVCu200 and TCu220C was significantly lower than that for SSR. Failure risks were associated with age at insertion, the types of IUD in this study and pregnancy frequencyprior to insertion,and failure risk in SSR was still higher than in VCu200 and TCu220Cat the end of the eighth year. The study revealed that TCu220C was of good long-termsafety,efficacy,and acceptability.展开更多
基金Project(22A0117)supported by Hunan Provincial Department of Education,ChinaProject(AWJ-20-M02)supported by State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,China。
文摘The effect of aging temperature on erosion corrosion （E-C） behavior of 17-4PH stainless steels in dilute sulphuric acid slurry containing solid particles was studied by using self-made rotating E-C apparatus. The effect of impact velocity on EC behavior of 17 4PH steels at different aging temperatures was analyzed. Surface micrographs of the specimens after E C test were observed by using scanning electron microscope （SEM）. The results showed that under the condition of the same solution heat treatment, when aging temperature ranged from 400 ℃ to 610℃, the hardness reached the highest value near the temperature 460℃. The characteristics of E-C for 17-4PH stainless steels at different aging temperatures were as follows： pure erosion （wear） was dominant, corrosion was subordinate and at the same time corrosion promoted erosion. The effect of aging temperature on E-C rate of 17-4PH steels was not significant at low impact velocity, but it was found that E-C resistance of 17-4PH steels aged near 460℃ was the most excellent due to the best precipitation strengthening effect of fine and dispersed e-Cu phase. With a prerequisite of appropriate corrosion resistance, the precipitation hardening could significantly improve the E-C resistance of the materials.
文摘The investigation on lath martensitic transfor- mation has been carried out for 24SiMnNi2CrMoA steel using transmission electron microscopy (TEM) and X-ray diffraction.The austenite and martensite in the alloy adopt the intermediate orientation relationship between Kurdjumov-Sachs and Nishiyama.The adjacent laths in a packet are small-angle related or twin-related.The retained austenites which accommodate shape deformation of martensites appear commonly between adjacent laths.High Si content increases the volume fraction of retained austenites and its stability.The excellent combination of high strength and toughness of this steel is attributed to its fine martensite laths mingled with more than 5% continuous retained austenite films.
文摘汽车行业的迅速发展使得能源消耗、环境污染等问题日益严重,而开发高强度且轻量化的汽车用钢对节能减排具有重要意义。目前正在研发的第三代先进高强钢包括轻质(Lightweight)钢、Q&P(Quenching and partitioning)钢和中锰钢(Mn质量分数为5%~10%)。其中,Fe-Mn-Al-C系低密度高强钢由于Al元素的加入,在密度降低的同时保持着良好的力学性能,满足第三代汽车用钢对轻量化的要求。同时,由于大量Al、Mn和C元素的添加,Fe-Mn-Al-C系低密度钢的冶炼连铸、微观结构、变形机制、加工过程及应用性能与传统钢种大不相同。本文系统阐述了Fe-Mn-Al-C系低密度钢的成分设计及其中合金元素的作用,介绍了低密度钢的微观组织结构特征;重点讨论了单一铁素体钢、奥氏体基钢、奥氏体基双相钢和铁素体基双相钢的各种强韧化机制,包括固溶强化、细晶强化、沉淀强化及其独特的应变硬化机制,如相变诱导塑性(TRIP)、孪晶诱导塑性(TWIP)、微带诱导塑性(MBIP)、剪切带诱导塑性(SIP)和动态滑移带细化(DSBR)等;并就层错能(SFE)对奥氏体钢变形机制产生的影响进行了总结;最后,对Fe-Mn-Al-C系低密度钢的强韧化机制研究进行展望,为后续研究者的工作提供参考。
文摘The Stainless steel ring(SSR),VCu200 and TCu220C were ic randomized comparison for eight years in a cohort of 4,490 subjects covering 16 centres in 9 provinces andmunicipalities.The follow-up rate at the end of the eithth year was 90.33%.The cumulative continuation rates were 47.06 per 100 women at the end of foe eighth year for SSR,54.05 for VCu200 and 61.14 for TCu220C.The cumulative pregnancy rates for VCu200and TCu220C were 10.35 and 8.94 per 100 women respectively,significantly lower than24.14 for SSR. There were significant differences in eight-year expulsion rates amongSSR(21.69%),VCu200(13.05%)and TCu220C(7.48%).The removal for bleedingand/or pain was the lowest in SSR;and no signaificant differences were found betweenVCu200 and TCu200C.but foe rate ws getting higher in VCu200 at the end of the eighthyear than in TCu220C.The discontinued use of IUD for desire to become pregnant in rural area was extremely higher than in urban area. The risk of pregnancy and expulsionwas in association with the types of IUD in this study,age at insertion,previous use ofIUD and pregnancy frequency prior to insertion. The risk of pregnancy and expulsion forVCu200 and TCu220C was significantly lower than that for SSR. Failure risks were associated with age at insertion, the types of IUD in this study and pregnancy frequencyprior to insertion,and failure risk in SSR was still higher than in VCu200 and TCu220Cat the end of the eighth year. The study revealed that TCu220C was of good long-termsafety,efficacy,and acceptability.
