自攻螺钉控制气氛浅层渗碳及其气氛选择

Shallow Carburizing of Self-tapping Screws in Controlled Atmosphere and Atmosphere Selection

自攻螺钉渗碳淬火处理的特点是连续化、大批量,要求节能、环保和低成本。此外,自攻螺钉要求浅层渗碳,且硬化层深度要严格控制。鉴于自攻螺钉的表面积与质量之比很大,其渗碳淬火宜选用无马弗网带炉生产线,采用碳传递系数较大的甲醇裂解气作载气,选用碳当量低且价廉的甲苯或丙烷作富化气,采用氧探头检测炉气氛碳势。以生产实例对此做了说明。

Carburizing and hardening of self-tapping screws are characterized by continuous production and mass pro duction,and are required to save energy,to reduce pollutant discharge,and to decrease production cost.In addition,the self-tapping screws are to be thin carburized,and their hardened case depths are to be strictly controlled.In view of the large ratio of surface area to weight,in carburizing and subsequently hardening self-tapping screws,a muffle-free mesh belt furnace production line is suitably selected;cracked methanol should be used as the carrier gas;low carbon equivalent and cheaper toluene or propane may be used as enriching gas;oxygen probe is to be used in measuring the carbon potential of furnace atmospheres.The above mentioned points were illustrated by a production example.