Present Situation of the Anti-Fatigue Processing of High-Strength Steel Internal Thread Based on Cold Extrusion Technology:A Review

The adoption of cold-extrusion forming for internal thread net forming becomes an important component of anti-fatigue processing with the development of internal thread processing towards high performance, low cost and low energy consumption. It has vast application foreground in the field of aviation, spaceflight, high speed train and etc. The internal thread processing and anti-fatigue manufacture technology are summarized. In terms of the perspective of processing quality and fatigue serving life, the advantages and disadvantages of the processing methods from are compared. The internal thread cold-extrusion processing technology is investigated for the purpose of improving the anti-fatigue serving life of internal thread. The superiorities of the plastic deformation law and surface integrity of the metal layer in the course of cold extrusion for improving its stability and economy are summed up. The proposed research forecasts the develop- ment tendency of the internal thread anti-fatigue manufacturing technology.

The Second International Conference on HSLA Steels

GENERAL INFORMATIONThe Chinese Society of Metals is pleased to announcethat The Second International Conference on HSLASteels(HSEA’90)will be held in Beijing,China inOctober 1990.Much progress in research and devel-opment of HSLA steels has been achieved by theworld’s metallurgical and materials community sincethe previous International Conference HSLA Steels’85 was held in Beijing,The aim of the conference isto review and to consolidate the scientific,metallurgical,and economical results and to assessthe future trend of development in the fields.

Preliminary Announcement for the Second International Conference on HSLA Steels

General Information The Chinese Society of Metals ispleased to announce that The SecondInternational Conference on HSLA Steels(HSLA ’90) will be held in Beijing, Chinain October, 1990. Much progress in researchand development of HSLA steels has beenachieved by the world’s metallurgical andmaterials community since the previousInternational Conference HSLA Steels ’85

The Second International Conference on HSLA Steels——Beijing,China,October 1990 Organized by THE CHINESE SOCIETY OF METALS

GENERAL INFORMATIONThe Chinese Society of Metals is pleased to announcethat The Second International Conference on HSLASteels (HSLA’90) will be held in Beijing,China inOctober 1990.Much progress in research and devel-opment of HSLA steels has been achieved by theworld’s metallurgical and materials community since

The Second International Conference on HSLA Steels Beijing,China,October 1990 Organized by THE CHINESE SOCIETY OF METALS

GENERAL INFORMATIONThe Chinese Society of Metals is pleased to announcethat The Second International Conference on HSLASteels(HSLA’90)will be held in Beijing,China inOctober 1990.Much progress in research and devel-opment of HSLA steels has been achieved by theworld’s metallurgical and materials community since

Effect of Intergranular Precipitation on the Internal Oxidation Behavior of Cr–Mn–N Austenitic Stainless Steels

The effect of intergranular precipitation on the internal oxidation behavior of Cr–Mn–N austenitic steels at 1000 °C in dry air atmosphere was investigated using scanning electron microscope, transmission electron microscope, and X-ray diffraction analysis. The results show that intergranular M23C6 carbide morphologies play an important role on the internal oxidation behavior of Cr–Mn–N steels. During the period of the oxidation, both discontinuous chain-shaped and continuous film-shaped intergranular M23C6 carbides precipitated along the grain boundaries. Internal oxides of silica preferentially intruded into the matrix along grain boundaries with discontinuous M23C6 carbide particles, while silica was obviously restricted at the interfaces between the external scale and matrix on the occasion of continuous film-shaped M23C6 carbides. It is seemed that reasonable microstructure could improve the oxidation resistance of Cr–Mn–N steels.

Interstitial Solution Carbon Concentration and Defects of Ti+Nb ULC-BH Steel by Internal Friction and Positron Annihilation Methods

The interstitial solution carbon concentration and defects in continuously annealed Ti＋Nb bearing ULC- BH （ultra-low carbon bake hardening） steel samples are investigated by multi-functional internal friction apparatus, positron annihilation lifetime spectroscopy （PALS） and coincidence Doppler broadening spectroscopy （CDBS）. The relationship of internal friction peaks, interstitial solution carbon concentrations and movable dislocations in the sam- ples under different conditions is analyzed. A correlation of lifetime component v~ values with interstitial solution car- bon concentrations in the samples for different continuous annealing processes is established, while a correlation of li- fetime component r2 values with multi-vacancies, vacancy clusters, microvoids and other types of defects for various continuous annealing processes is also demonstrated. Furthermore, the average lifetime results illustrate the overall defect densities for various continuous annealing processes. The CDBS analysis reflects the chemical surroundings of the defects at the annihilation sites and reveals that the peak heights of the ratio curves relate to the total number of defects such as interstitial carbon atoms, dislocations, vacancies and other types of defects. The results show that in- ternal friction, PALS and CDBS are effective techniques to identify and characterize the interstitial solution carbon concentration, multi-vacancies, vacancy clusters, microvoids and other types of microscopic defects in annealed Ti＋ Nb bearing ULC-BH steel.