Method of making high strength cold reduced steel by continuous annealing process

In a method of making a high strength cold reduced steel with a continuous annealing process, the improvement which comprises:

• maintaining the chemical composition of the steel in the steel making stage within the following ranges:
• C:
• 0.04 to 0.10%,
• P:
• 0.04 to 0.20%,
• S:
• not more than 0.02%,
• Mn:
• [S]% .times. 10 to 0.70%,
• balance:
• Fe and impurities;
• hot rolling and cold reducing the steel, and subjecting the resulting cold reduced steel to a continuous annealing process comprising the following heat cycle:
• i. heating the resulting cold reduced steel to and maintaining the heated steel at a temperature of from Ac.sub.1 to 900.degree. C. for from 10 to 120 seconds,
• ii. quenching the steel of (i) which is at a temperature of from Ac.sub.1 to 900.degree. C. with a jet stream of water,
• iii. tempering the quenched steel at a temperature of from 200.degree. C. to 500.degree. C. for from 10 to 180 seconds, and
• iv. cooling and coiling the tempered steel,
• the steel so obtained having a Lankford value of at least 1.1, tensile strength of from 40 to 80 kg/mm.sup.2, elongation of more than 20% and spot weldability of more than 900 kg/spot.