强被迫伦姧惨叫在线视频,99久久国产精品免费,成人免费无码大片A毛片,2020日本不卡一区二区视频,高潮后的少妇中文字幕,小草在线观看免费视频,欧美日韩免进入,又黑又粗又爽的免费视频,天天综合网久久综合免费人成,美女粉嫩喷水在线看,国产午夜一区二区三区,Jiz国产精品免费麻豆,欧美黑人性猛交XXXXⅩOOO ,亚洲中文字幕国产综合,亚洲综合成人婷婷五月网址 ,妈妈的朋友在线观看清

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.