The Mitigation of Weld Residual Stress on 304L Stainless Steel by Post Weld Cool Treatment Process

The High Welding Residual Stress is the Main Factors Affecting the Service Life of Welded Structures. Post Weld Cool Treatment (PWCT) is a Novel Method by Introducing Reverse Process Welding Temperature Field to Eliminate the Residual Stress and to Obtain Compressive Stress Layer. the Major Factors Affecting the Effects of Post Weld Cool Treatment (PWCT) is Preheating Temperature, Cooling Time and Cooling Range. in this Paper, a Model to Calculate the Residual Stress was Built Using Finite Element Code ABAQUS, and Different PWCT Processes were Applied on 304L Stainless Steel Specimens. at the same Time, Impact Indentation Method (IIM) was Used to Measure the Residual Stress on the Specimens. the Results Show that the Longitudinal Stress and the Transverse Stress were Reduced Obviously and Compressive Stress was Generated after PWCT in both of the Simulation and the Experiment. the Proposal Preheating Temperature was 400°C and the Cooling Range was 2 Times of Weld Width. Besides, the Cooling Time had Little Effect on the Residual Stress.

487 Strategies to Enhance Production of Annual Globe Artichoke

Annual production of globe artichokes (Cynara scolymus L.) requires vernalization of the plants, either through cold treatment of transplants or from natural temperature conditions in the spring. Studies were conducted in upstate New York to determine if artificial vernalization treatments could be achieved by earlier planting dates. Initial trials evaluated two cultivars used for annual production in other parts of the country—'Imperial Star' and `Green Globe Improved'. Transplants were set in the field with or without a vernalizing cool treatment, to determine the extent of natural vernalization achieved under New York conditions. `Imperial Star' produced slightly higher marketable yields than `Green Globe Improved' in 2 years of trials. Vernalization treatment increased the number of plants producing buds and the marketable yields, when transplants were set after 15 May. Natural vernalization was achieved and cold treatment prior to transplanting did not improve yields of plants established in early May. At later planting dates, vernalizing transplants increased the number of plants producing apical buds (largest) by about 20%, yet, >57% of non-vernalized plants of each variety produced buds within the season. Average bud sizes did not vary with vernalization treatment. A similar number of days from transplanting to first bud harvest (69 to 75) was noted regardless of planting date and size of transplant.

Vernalization Strategies to Enhance Production of Annual Globe Artichoke

Annual production of globe artichokes (Cynara scolymus L.) requires vernalization of the plants, either through cold treatment of transplants or from natural temperature conditions in the spring. Studies were conducted in upstate New York, to determine if artificial vernalization treatments could be achieved by earlier planting dates. Initial trials evaluated two varieties used for annual production in other parts of the country—`Imperial Star' and `Green Globe' Improved. Transplants were set in the field with or without a vernalizing cool treatment, to determine the extent of natural vernalization achieved under New York conditions. `Imperial Star' produced slightly higher marketable yields than `Green Globe Improved' in 2 years of trials. Vernalization treatment increased the number of plants producing buds and the marketable yields, when transplants were set after 15 May. Natural vernalization was achieved and cold treatment before transplanting did not improve yields of plants established in early May. At later planting dates, vernalizing transplants increased the number of plants producing apical buds (largest) by about 20%, yet over 57% of nonvernalized plants of each variety produced buds within the season. Average bud sizes did not vary with vernalization treatment. A similar number of days from transplanting to first bud harvest (69 to 75 days) was noted regardless of planting date and size of tran.

A Model Describing rRelease of Flower Bud Dormancy in `Prize' and `Gloria' Azaleas

`Prize' and `Gloria' azaleas were budded at 29C day/24C night without growth regulators. Dormant-budded plants were held at 2, 7, 13, or 18C for 0, 0.5, 1, 2, 4, 6, 8, or 10 weeks and then forced in walk-in growth chambers (29C day/24C night). A model was developed to describe the effect of cooling temperature and duration on days to marketability (eight open flowers) and percent of buds showing color. Holding at temperatures below 7C, increases days to marketability up to 7 days. Extended cooling (beyond 6 weeks) at temperatures <7C increases percent of buds showing color. Extended holding at temperatures >7C decreases buds in color due to development of bypass shoots during cooling and increased bud abortion. Plants not receiving a cool-treatment or cooled for <2 weeks do not flower uniformly. Furthermore, the percentage of plants reaching marketability dramatically decreases for plants held longer than 6 weeks at temperatures >7C. Both cultivars show similar trends, but `Gloria' has greater variability.

Temper Embrittlement in 2-1/4 Cr-1 Mo Steels After 75,000-Hour Isothermal Aging

A long-term laboratory study has confirmed that temper embrittlement (TE) in 2-1/4 Cr-1 Mo plate, forgings, and weldmetals levels off over time. Fifty-five heats of 2-1/4 Cr-1 Mo steel from several vendors were aged for up to 75,000 hours at 427 to 482°C (800 to 900°F), and extent of embrittlement was determined from shifts in 54 J (40 ft-lb) transition temperature for each heat. Embrittlement levelled off within 35,000 hours at 427°C (800°F) and 454°C (850°F), and within 10,000 hours at 482°C (900°F). Plate material embrittled least, while submerged arc and shielded metal arc weldments embrittled most. Although steel chemistry has previously been used to predict TE susceptibility, our analysis of these 55 heats, and of 23 heats of 2-1/4 Cr-1 Mo in a 1982 API study, shows that a step-cool treatment simulating long-term exposure is a more reliable way to screen susceptible materials.

Variation in lodgepole pine (Pinuscontorta var. latifolia): greenhouse response of wind pollinated families from five populations to day length and temperature–soil

Seeds were collected from 10 lodgepole pine trees in each of five stands located in Utah, Montana, Idaho, Washington, and British Columbia. Seeds were planted and seedlings grown in four day-length regimes (14, 15.5, 16.5, and 22 h) in each of two temperature regimes (warm and cool). Soils used in the warm and cool treatment were slightly different. Height and dry weight were recorded.Variability among families within populations was considerably greater than that among populations. If interactions between families of the two cone types (open and closed) are removed, correlation between among-family variance and differential family response to day length and temperature–soil treatments is strong for dry weight (r2 = 0.96), and less strong for height (r2 = 0.51). Families from open- and closed-cone mothers did not have different heights and dry weights, but in at least some of the populations were different in the degree of among-family variability.Correlation between greenhouse and 5th-year heights of field planted seedlings was poor for individual families, but good (r2 = 0.92) for mean population heights. Correlation between 5th-year mean population heights and site index of the parent stand was also good (r2 = 0.89).