重点叙述了国内外内燃机油燃料经济性能及油品规格的要求，介绍了评价燃料经济性的试验方法。
Fuel economy performance and some the latest specifications of inter-combustion engine oil at home and abroad are recounted. Test method of fuel economy performance is introduced.
应力松弛试验是一种常用于测定粘弹性材料性能及粘弹性参数的试验方法。
Stress slack tests are often used in determining the properties of viscoelastic materials and viscoelastic parameters.
介绍了超低碳贝氏体wdb620钢的力学性能，用几种传统的焊接性试验方法对该钢焊接接头的力学性能及抗裂性进行了研究。
The mechanical properties of steel WDB620 are introduced. Some traditional tests about the mechanical properties and cracking resistance on its welded joint have been made.
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