TOI BE MAT:

Toi be mat la phuong phap toi bo phan kim loai khi do chi co lop be mat chi tiet duoc toi, con loi khong dc toi.sau khi toi chi co lop be mat co to chuc mactenxit, con nhung nuoc ben trong co to chuc xoocbit-peclit.

+phuong phap: co nhiu phuong phap toi be mat, nhung noi chung chung deu dua vao nguyen ly nung nong be mat that nhanh voi chiu sau nhat dinh den nhiet do toi roi lam nguoi nhanh.khi do phan be mat duoc nung nong va toi, phan loi khong dc nung nong va khong duoc toi.ket qua la nhan dc be mat cung,trong loi deo.

Toi be mat thong dung nhat bang phuong phap nung cam ung o cac lo tan so.Mot cach khac de nung la dung ngon lua axetylen(han hoi).

Toi thep nham cac muc dich sau:

+nang cao do cung va tinh chong mai mon cua thep, do do nang cao tuoi tho cua chi tiet may.chu y la do cung cua thep toi chi phu thuoc vao ham luong cac bon trog thep.vi vay, thep co ham luong C wa thap(<=0.25%) sau khi toi thuong k dat do cung can thiet

+nang cao do ben va do do tang suc chiu tai cua chi tiet may.hau het cac chi tiet may quan trong deu phai wa toi.tuy nhien,cac muc dich tren chi dat khi ket hop toi va ram.

-doi voi thep cacbon, nhiet do toi duoc tuy thuoc vao ham luong C va thanh phan cua thep.

-doi voi thep truoc cung tich va cung tinh (C<= 0.8%) nhiet do toi dc chon T=Ac3+(30-50do) khi luong C tang len, nhiet do toi giam di.day la phuong phap toi hoan toan

doi voi thep toi sau cung tich (C>0.8%) nhiet do toi dc chon T=Ac1+(30-50do) khi C tang len, nhiet do toi k doi.tuong ung la phuong phap toi k hoan toan.