China University of Petroleum

Shandong Tu

Wenchun Jiang

Jianming Gong

Lei Ge

Chaohe Yang

Yucai Zhang

Xiancheng Zhang

Qiang Jin

Xuefang Xie

Wenbin Gu

Xiang Ling

A primary heating band is applied to a weld to control a microstructure and hardness of the weld and uniformity of the structure to realize micro-control of the residual stress; an auxiliary heating band is applied a certain distance away from the weld to generate compressive stress on an inner surface of the weld to realize macro-control of the compressive stress. Reinforcement with a rib plate is eliminated, and a labor intensity and a construction period are reduced. The method reduces deformation near the weld and transfers the largest deformation to a non-weld zone; by applying the auxiliary heating and strictly controlling a time interval between primary heating and auxiliary heating, the structure is improved and the welding residual stress is controlled at the same time; a local heat treatment effect is optimized, and a small tensile stress or compressive stress is generated on the inner surface of the weld.

Local heat treatment method for controlling residual stress with primary and auxiliary heating

A method for homogenizing the compositions and mechanical performances of nickel-based material brazed joints, includes three homogenized manufacturing steps: Step I, assembling the welding sample, placing it into the vacuum furnace, and then heating up to 830&#x2dc;860&#xb0; C. and holding the temperature; then heating up again to 1050&#x2dc;1100&#xb0; C. and holding the temperature; allowing for slow self-cooling in vacuum till it reaches 620&#x2dc;640&#xb0; C.; then filling the furnace with nitrogen and starting the vacuum furnace fan at the same time, so that the sample is cooled down to 40&#x2dc;60&#xb0; C.; Step II, raising the temperature up to 1140&#x2dc;1160&#xb0; C. and holding, then cooling it down to the room temperature through water-quenching; Step III, raising the temperature of the welding sample up to 680&#x2dc;750&#xb0; C. again, and cooling it down to the room temperature through air cooling.

Method for homogenizing the compositions and mechanical performances of nickel-based material brazed joints

A design method for creep-fatigue strength of a plate-fin heat exchanger. The method includes preliminarily designing the plate-fin heat exchanger according to its service requirements, making a primary stress assessment for the plate-fin heat exchanger, calculating the equivalent mechanical and thermophysical parameters of the plate-fin heat exchanger core to satisfy the allowable stress requirement, performing a thermal fatigue analysis for the plate-fin heat exchanger based on these parameters and then calculating the fatigue life and creep life of the plate-fin heat exchanger to accomplish the comprehensive design of the plate-fin heat exchanger in the high-temperature service. The design method provides an effective method for the high temperature design of the plate-fin heat exchanger.

Method for creep-fatigue strength of plate-fin heat exchanger

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Qingdao, China

Shandong Tu