丹丹忍一忍让我再进去一下,1区1区产品乱码芒果榴莲,三年在线观看免费大全下载 ,国产美女一级做视频爱,天美麻花视频大全,人人入人人爱,亚洲国产精品久久久久婷蜜芽,首页动漫亚洲欧美日韩,一二三四日本免费,精品乱码久久久久久久,色综合久久88色综合天天

Stainless steel head in the heating and cooling process, the cooling rate is inconsistent surface and center and time, forming temperature, resulting in volume expansion and contraction of the uneven stress that the heat stress. Stainless steel head under the effect of thermal stress due to a temperature below the surface began to core section, leaving the central portion is greater than the contraction also central portion tension, when the end of the cooling, since the cooling core section final volume shrinkage can not freely leaving the surface layer by Ministry press center of tension. That is under the influence of thermal stress and finally to the workpiece surface pressure and heart Ministry tension. This phenomenon is cooled velocity, material composition and heat treatment and other factors.

 

When cooled, the faster, the higher the carbon content and alloy composition, inhomogeneous plastic deformation of the cooling process in the thermal stress generated by the larger, the final form of the residual stress is greater.

On the other hand the steel during heat treatment due to the change in the organization that is the transformation of austenite to martensite, accompanied by the increase of the specific volume of the volume expansion of the workpiece, the various parts of the workpiece has a phase change, resulting in inconsistency of the volume of tissue grown stress.

 

The end result stainless steel head the surface tissue stress is tensile stress, the heart portion compressive stress, and thermal stress exactly the opposite. The stress in the workpiece size and cooling rate of martensite transformation zone factor, shape, chemical composition of the material.