SR Treatment Research Articles

401 Cr-Mo鋼母材の低延性クリープ破壊におよぼすSR処理の効果(材料力学-材料の疲労と破壊)

401 Cr-Mo鋼母材の低延性クリープ破壊におよぼすSR処理の効果(材料力学-材料の疲労と破壊)

A Simple Estimating Method for Reduction of Welding Residual Stresses in Thick Welded Joint From Stress-Relief Annealing—Part II: The Characteristics of Reduction of Welding Residual Stresses in Very Thick Joints During SR Treatment

Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels, etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In the first report, an estimating method was developed for relaxation tests, in uniaxial stress state, at changing and constant temperatures because the stress relaxation phenomenon is considerably similar to that observed in the SR treatment of a joint. In this report, the stresses relaxed by SR treatment in a very thick welded joint are analyzed accurately by the finite element method based on thermal elastic-plastic-creep theory. The characteristics of the changes of the welding residual stresses in multiaxial stress state are studied in detail for further development of the estimating method to SR treatment of a very thick welded joint, of which the stress state and boundary condition are very complex.

Temper embrittlement in the HAZ of 2¼ Cr-1Mo steel induced by reheating after SR treatment: Study of temper embrittlement in HAZ of Cr-Mo steels (4th report)

Summary The temper embrittlement affecting the HAZ of 2 1/4Cr-1Mo steel subjected to SR treatment and subsequent reheating is investigated with synthetic HAZ specimens and compared with the embrittlement observed in specimens tempered in the same temperature range without SR treatment (direct tempering). The synthetic HAZ specimens are de-embrittled on application of suitable SR treatment (975 K × 5 hours). Subsequent reheating at 775 to 925 K, however, produces four different types of embrittlement in the specimens. These are the second, third, fourth, and fifth types of embrittlement already identified in the direct-tempered specimens. The first type of embrittlement which occurs during direct tempering in the shortest time range does not appear after SR treatment. The second type (the short-term type), which occurs over a wide time-temperature range during direct tempering, only appears in a narrow range after SR treatment. The third and fourth types (the long-term types) occur just as intensively as during direct tempering. The fifth type (the high-temperature type) also appears after SR treatment. This suggests that embrittlement in the short-term range is to some extent suppressed by SR treatment, but the types of embrittlement arising in the long-term range and high-temperature range occur after SR treatment as well. The ‘step cooling process’ can be applied for short-term detection of temper embrittlement in this steel. However, there is considered to be little or no embrittlement promotion effect due to step cooling per se.

Winter soil microclimate altered by corn residue management in the northern Corn Belt of the USA

Management of crop residue is important for promoting soil water recharge and early spring thaw in the northern Corn Belt of the USA. This study assessed the impact of residue management in no tillage, continuous corn ( Zea mays L.) production systems on the soil thermal and water regime during winter in west central Minnesota. Residue treatments were initiated in the fall over three years and included the removal of stubble and loose residue (RR) from the soil surface, all residue lying prostrate (PR) on the soil surface, and stubble standing and loose residue lying (SR) on the soil surface. Soil (to 0.3 m depth) temperatures were recorded hourly whereas soil water content, frost depth, and snow cover were measured weekly. The SR treatment effectively trapped more snow, which resulted in warmer soil (2°C or less), shallower frost penetration (as much as 0.5 m), and earlier soil thaw (up to 20 d) as compared with the RR or PR treatments. Winter soil temperatures and depth and duration of soil freezing were the same for the RR and PR treatments. Soil water content was the same for all treatments prior to fall freezing, but was less for the PR treatment than for the SR or RR treatment during winter due to less snowmelt infiltration for the PR treatment. Corn production utilizing no tillage in the northern USA necessitates the retention of stubble on the soil surface for promoting warmer soil during the winter as well as earlier spring thaw as compared with removing or chopping stubble.

Ｃｒ‐Ｍｏ鋼熱影響部の焼もどし脆化に関する研究 第４報 ＳＲ処理後の再加熱によって２ １／４Ｃｒ‐１Ｍｏ鋼ＨＡＺに生じる焼もどし脆化

Temper embrittlement, which occurs in HAZ of 2 1/4Cr-1Mo steel subjected to SR treatment and subsequent reheating, was investigated by using synthetic HAZ specimen, and it was compared with embrittlement observed in specimens tempered in same temperature range without SR treatment (direct tempering). With a suitable SR treatment (975 K for 5 hours) synthetic HAZ specimen became de-embrittled state. However, subsequent reheating at 775 to 925 K produced in specimens four different types of embrittlement. Those were second, third, fourth and fifth types, which had already been recognized in direct tempered specimens. The first type of embrittlement which arose in direct tempering in shortest time range did not appear after SR treatment. The second type (the short time type), which occurred in a wide time-temperature range in direct tempering, arose only in a narrow one after SR treatment. The third and fourth types (the long time types) arose intensively as case of direct tempering. The fifth type (the high temperature type) appeared also after SR treatment. It will be concluded that embrittlement in short time range is suppressed to some extent by SR treatment, but those arising in long time range and high temperature one arose after SR treatment as well. It was found that the step-cooling also could reveal temper embrittlement of this steel. However, an essential advantage of this process over isothermal tempering shown above was not recognized from view point of promoting embrittlement.

Temper embrittlement in HAZs of Cr-Mo steels in SR treatment temperature range: Study of temper embrittlement in HAZs of Cr-Mo steels (3rd Report)

Summary Temper embrittlement in the high-temperature range affects the heat affected zone (HAZ) when the welded structures of Cr-Mo steels are subjected to SR heat treatment (stress relief annealing)in the temperature range above 900 K. It has been previously shown that there arc four types of temper embrittlement in the temperature range below 900 K. This paper describes an investigation of temper embrittlement of the high-temperature type (fifth type) affecting 2 1/4Cr-1 Mo steel and 1 1/4Cr-1/2 Mo steel in conjunction with the other four types. Charpy impact tests are conducted with synthetic HAZ specimens tempered at 900 K to 1000 K. The experimental results show that 2 1/4Cr-1 Mo steel may be embrittled by SR treatment because the SR temperature of this steel (about 975 K) corresponds to that at which the fifth type arises. A shorter holding time is recommended to avoid temper embrittlement. 1 1/4Cr-1/2 Mo steel is more likely to be affected by the third type rather than the fifth type, because the SR temperature of this steel (about 925 K) corresponds to that at which the third type arises. The role of carbide particles in inducing the fifth type of embrittlement is discussed in some detail.

Effect of strontium on chlorophyll content, peroxidase activity, and iron distribution in cell walls

An investigation was conducted to investigate the effect of strontium on peroxidase (POD) activity and chlorophyll (Chl) degradation in sugar beets (Beta vulgaris). Peroxidase activity was considerably increased by 10 mM strontium (Sr) addition to a Hoagland nutrient solution without additional application of calcium (Ca). When grown in a Hoagland nutrient solution containing both 5 mM Ca and 5 mM Sr, POD activity in all leaves and roots decreased, whereas Chl content per g fresh weight (f.w.) was increased slightly compared to POD activity and Chl contents in plants treated with calcium alone. Chla/b ratios were also affected by Sr treatment. Both Sr and Ca contents were higher in older leaves than in younger leaves. Cation spectra obtained by a laser microprobe mass analyzer indicated that the intensity of sodium (Na) and potassium (K) peaks were greatly reduced by EDTA and EGTA treatments, but those of Ca, Sr, and magnesium (Mg) peaks were not.

Ｃｒ‐Ｍｏ鋼熱影響部の低延性クリープ破壊に関する研究 第１報 ２ １／４Ｃｒ‐１Ｍｏ鋼再現ＨＡＺ試験片の低延性クリープ破壊およびＳＲ処理の効果

Low-ductility fracture (LDF) occurred occasionally in the heat affected zone (HAZ) when the welded constructions of Cr-Mo steels were subjected to the long time services at high temperature. The LDF in 21/4Cr-lMo steel was reproduced in the laboratory by the creep rupture test in the temperature range of 775 to 875 K. The tests were made on synthetic HAZ specimens of the original and SR-treated conditions. SR treatment was carried out at 975 K for 2 hours. The ductility shown by the reduction in area of the specimen was discussed in relation to the time to fracture and the fracure mode.Two different types of LDF were recognized in HAZ specimen in the original condition. The first type of LDF appeared in the short term range of rupture producing a typical intergranular fracture (the fracture of type I). The second type appeared in the long term range of rupture, longer than a critical time period, tf, producing another type of intergranular fracture (type II). In this type of fracture, fractures occurred along grain boundaries accompanying a significant deformation of ferrite grains. A small quantity of ductile fracture of type III was usually accompanied to those fracture types.SR-treated specimen fractured with ductile manner in the short term range of rupture, but it lost the ductility when the time exceeded a critical time period, tsr, which was approximately the same as the time tf. The fracture of type II appeared in this time range. Those results informed that, (1) the LDF in short term range, which produced the type I fracture, disappeared after SR treatment, (2) the LDF in long term range, which produced the type II fracture, revived even after the SR treatment.

Effects of tempering conditions on temper embrittlement of the HAZ in 1 1/4Cr-1/2Mo steel: Study of temper embrittlement of the HAZ in Cr-Mo steels (2nd Report)

Summary This paper describes an investigation of the temper embrittlement of the heat affected zone (HAZ) in 1 1/4Cr-1/2Mo steel in the tempering temperature-time range 775–900 K and 5–10 000 hours. The temper embrittlement is detected as an increase in energy at the transition temperature. Three types of embrittlement -the second, third, and fourth types of embrittlement observed in 2 1/4Cr-1 Mo steel - are identified. The third type of embrittlement is the same as reversible temper embrittlement (RTE), whereas the other two are new types, being characterised by their own transition curve shapes and fracture surface appearances. The third and fourth types of embrittlement in this steel appear later than in 2 1/4Cr-1 Mo steel. The effect of stress on the tempering process is examined in this investigation. It increases the magnitude of the third type of embrittlement but does not affect the second type. SR-treated specimens are also examined in this investigation. When specimens de-embrittled by SR treatment are reheated, they are re-embrittled. Reaching this de-embrittled state at 825 K induces two different types of re-embrittlement. One is the third type of embrittlement (RTE) exhibiting intergranular fracture. The other type exhibits cleavage fracture, but it is not known whether or not this type belongs to the third type.

A Simple Estimating Method for Reduction of Welding Residual Stresses in Thick Welded Joint From Stress-Relief Annealing—Part I: Development of the Analytical Method for Relaxation Tests and Its Applicability

Stress-relief annealing (SR treatment) is often applied to relieve welding residual stresses in the fabrication process of pressure vessels, etc. This study aims at development of an efficient method as simple as hand calculation to estimate reduction of residual stresses of very thick welded joint by SR treatment. In this first report, an estimating method is developed for relaxation tests, in uniaxial stress state, at changing and constant temperatures because the stress relaxation phenomenon is very similar to that observed in the SR treatment of a joint. Using the various relations between stress and strains in the relaxation tests, estimating equations are formulated in order to simply calculate the change of the stress. The results obtained by applying the equations are compared with the highly accurate analytical result based on the finite element method. Both results show such a good coincidence that the appropriateness of the adopted method is confirmed. In the next report, this method is extended to SR treatment of a very thick welded joint, of which the stress state and boundary condition are very complex.

１１／４Ｃｒ‐１／２Ｍｏ鋼熱影響部の焼もどし脆化におよぼす焼もどし条件の影響 Ｃｒ‐Ｍｏ鋼熱影響部の焼もどし脆化に関する研究 第２報

The temper embrittlement arising in the heat affected zone (HAZ) of 1 1/4Cr-1/2Mo steel was studied in the tempering temperature-time range of 775 to 900 K and 5 to 10000 hours. The temper embrittlement was detected as the rise of energy transition temperature. Three types of embrittlement were recognized; they are the second, third and fourth types of embrittlement which have been observed in 2 1/4Cr-lMo steel. The third type of embrittlement is same as the reversible temper embrittlement (RTE), but other two types are new ones observed by the authors. They are characterized by their own shapes of transition curves and appearances of the fracture surfaces. The third and fourth types in this steel appear later than in the case in 2 1/4Cr-1Mo steel. The third type in this steel continues to appear at a higher temperature than in the case in 21/4Cr-1Mo steel. The influence of stress in the tempering process was examined. It increases the magnitude of the third type of embrittlement, but does not affect the second type. Examinations were also made on the SR-treated specimen. SR treatment turns the HAZ specimen into the de-embrittled state, but reheating it at 825K induces two different types of embrittlement. One of them is the third type of embrittlement (RTE) which exhibits the intergranular fracture. The other type exhibits the cleavage fracture; it is not yet known whether it belongs to the third type or not.

Refractory Cardiogenic Shock and Complete Heart Block After Verapamil SR and Metoprolol Treatment

A seventy-eight-year-old woman presented with complete heart block and refractory hypotension two days after a therapeutic dose of sustained-release verapamil with concomitant use of metoprolol. The patient continued to remain hypotensive with complete heart block, even with multiple uses of intravenous atropine as well as high doses of pressor agents such as dopamine and dobutamine. However, shortly after the use of intravenous calcium chloride, the refractory hypotension and complete heart block resolved.

Restoration of Prostaglandin Releasing Macrophage Populations in Lethally Irradiated Mice With Spleen Cells From Bone Marrow-Depleted Donors

Previous studies in mice severely depleted of bone marrow cells by 89Sr showed persistent monocytopenia and impaired expression of prostaglandin E2-releasing splenic macrophages (PGSM) despite the occurrence in the spleen of more than 10-fold increases in pluripotential stem cells and M phi colony-forming cells. To determine whether the observed deficits were due to a lack of precursors of blood monocytes and PGSM in the spleens of 89Sr-treated mice, radiation chimeras were established by i.v. infusion of 2 x 10(6) spleen cells from 89Sr donor CBA/J or semisyngeneic B6CB F1 hybrid mice into lethally gamma-irradiated CBA/J recipients. Blood monocyte levels were greater than normal by day 14 and PGSM induced by Corynebacterium parvum were demonstrated by day 28. These restored M phi populations expressed the donor haplotype detected in vitro with haplotype-specific monoclonal anti-H-2K plus complement. 89Sr treatment of the chimeras resulted in profound depletion of monocytes and PGSM. The data indicate that the spleen of the 89Sr-treated mouse, which is an ineffective source of circulating monocytes and PGSM, contains cells which can generate both of these populations following infusion into lethally irradiated recipients. Since the bone marrow of such recipients was capable of being repopulated, the aggregate observations suggest that functional bone marrow is obligatory for the generation of blood monocytes and PGSM populations.

Double‐blind comparison of long acting propranolol and sustained release metoprolol in the treatment of angina pectoris

SummaryA double‐blind cross‐over trial was performed in 11 patients with stable angina, comparing the effect of two once‐daily long acting beta‐blocker formulations, Inderal LA (propranolol) and Lopresor SR (metoprolol), each given for a four week period.The patients' response to the two treatments was very similar and no significant differences were noted between the treatments. Patients may have benefited slightly more by Inderal LA therapy. Slightly fewer angina attacks and side effects were reported when the patients were receiving Inderal LA treatment, compared with Lopresor SR treatment. The patients' exercise tolerance, blood pressure and heart rate were assessed approximately 24 hours after the last dose of their once daily treatment. Inderal LA treatment may have allowed patients to exercise a little longer, and there was a trend towards slightly lower blood pressures and heart rates when the Inderal LA treatment period was compared with treatment during the metoprolol period.

心室性期外収縮に対するＭｅｔｏｐｒｏｌｏｌ徐放錠（ＣＦ‐１５ＳＲ）の単回投与時の影響について クロス・オーバー法によるＭｅｔｏｐｒｏｌｏｌ普通錠との比較

The comparative effectiveness of two dosage forms of metoprolol, the 120mg slow release tablet (SR) administered once daily and the 40mg conventional tablet (CO) given three times daily, on premature ventricular contraction (PVC) and heart rate (HR) was examined in patients with PVC of≥3, 000 beats/24 hr by employing a Holter ECG with a 24-hour monitor using a cross-over design, and changes with time in plasma concentrations after administration of SR and CO were measured.The mean of the PVC values which were monitored three times in the observation period under placebo was 710±184 beats/hr (Mean±S. E.) and the diurnal variation of PVC was high, averaging 34.2±6.5%. In the treatment periods, five patients showed significant reduction of PVC values by more than 25% in comparison to the placebo treated period in one of the intervals, showing reduction values during the whole day, the daytime, and the night-time of 37.8±13.3%, 46.5±15.1%, and-91.7±103.3% under SR, respectively. The reduction rates under CO tended to be higher in comparison to SR, showing 52.6±12.3%, 59.7±11.0% and 24.5±15.0%, respectively. No significant difference was noted between SR and CO . The duration of inhibitory effect on PVC was about 12 hours under SR and about 17 hours under CO.In the treatment periods, HR under both SR and CO was inhibited significantly in comparison with that in the observation period . No significant difference in inhibition of HR was seen between SR and CO. The inhibition on HR under CO was slightly higher than that under SR during the interval from night to early morning . These inhibitions were maintained over 24 hours.The plasma concentrations after administration of SR and CO did not show any significant difference. The plasma concentration level which is considered to be sufficient to inhibit HR was maintained even at 24 hours after administration of SR, (11.3±7.8ng/ml).In conclusion, SR maintained the inhibitory effect on HR for 24 hours similarly to that under CO, but was thought to be inferior to CO in its inhibitory effect on PVC . This may be due to the difference in the threshold plasma concentrations to inhibit HR and PVC and the lower plasma concentrations during night-time in the SR treatment period.