... mediumhard formations.YG614.9590.51900For coring crowns,electric coal drill bits, coal cutting picks,oil cone bits andscraping knife ... formation.YK1514.687.62450Suitable to strips, conical buttons for rotary percussion-resistant,geologicalprospectioin buttons, cut soft and medium hard ... YK2514.487.22550Primarily for the buttons and inserts of rotary percussion bits to cutmedium-hard and very hard ...