(c) 图209-1批齿轮金相组织 (a)HB250Ⅱ85~90%3%硝酸酒精浸蚀100× (b)HB241 Ⅱ80~85%3%硝酸酒精浸使 100× (c)H241 Π80一85%3%硝酸酒清浸独 500× 图309-2批齿轮金相组织 (a)HB236I70%3%硝酸酒精浸蚀100× (b)HB215Π60%3%硝酸酒精浸蚀 100×